i86pc/vm/vm_machdep.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1992, 2010, Oracle and/or its affiliates. All rights reserved.
 */
/*
 * Copyright (c) 2010, Intel Corporation.
 * All rights reserved.
 */

/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*	All Rights Reserved   */

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

/*
 * UNIX machine dependent virtual memory support.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/user.h>
#include <sys/proc.h>
#include <sys/kmem.h>
#include <sys/vmem.h>
#include <sys/buf.h>
#include <sys/cpuvar.h>
#include <sys/lgrp.h>
#include <sys/disp.h>
#include <sys/vm.h>
#include <sys/mman.h>
#include <sys/vnode.h>
#include <sys/cred.h>
#include <sys/exec.h>
#include <sys/exechdr.h>
#include <sys/debug.h>
#include <sys/vmsystm.h>
#include <sys/swap.h>

#include <vm/hat.h>
#include <vm/as.h>
#include <vm/seg.h>
#include <vm/seg_kp.h>
#include <vm/seg_vn.h>
#include <vm/page.h>
#include <vm/seg_kmem.h>
#include <vm/seg_kpm.h>
#include <vm/vm_dep.h>

#include <sys/cpu.h>
#include <sys/vm_machparam.h>
#include <sys/memlist.h>
#include <sys/bootconf.h> /* XXX the memlist stuff belongs in memlist_plat.h */
#include <vm/hat_i86.h>
#include <sys/x86_archext.h>
#include <sys/elf_386.h>
#include <sys/cmn_err.h>
#include <sys/archsystm.h>
#include <sys/machsystm.h>

#include <sys/vtrace.h>
#include <sys/ddidmareq.h>
#include <sys/promif.h>
#include <sys/memnode.h>
#include <sys/stack.h>
#include <util/qsort.h>
#include <sys/taskq.h>

#ifdef __xpv

#include <sys/hypervisor.h>
#include <sys/xen_mmu.h>
#include <sys/balloon_impl.h>

/*
 * domain 0 pages usable for DMA are kept pre-allocated and kept in
 * distinct lists, ordered by increasing mfn.
 */
static kmutex_t io_pool_lock;
static kmutex_t contig_list_lock;
static page_t *io_pool_4g;	/* pool for 32 bit dma limited devices */
static page_t *io_pool_16m;	/* pool for 24 bit dma limited legacy devices */
static long io_pool_cnt;
static long io_pool_cnt_max = 0;
#define	DEFAULT_IO_POOL_MIN	128
static long io_pool_cnt_min = DEFAULT_IO_POOL_MIN;
static long io_pool_cnt_lowater = 0;
static long io_pool_shrink_attempts; /* how many times did we try to shrink */
static long io_pool_shrinks;	/* how many times did we really shrink */
static long io_pool_grows;	/* how many times did we grow */
static mfn_t start_mfn = 1;
static caddr_t io_pool_kva;	/* use to alloc pages when needed */

static int create_contig_pfnlist(uint_t);

/*
 * percentage of phys mem to hold in the i/o pool
 */
#define	DEFAULT_IO_POOL_PCT	2
static long io_pool_physmem_pct = DEFAULT_IO_POOL_PCT;
static void page_io_pool_sub(page_t **, page_t *, page_t *);
int ioalloc_dbg = 0;

#endif /* __xpv */

uint_t vac_colors = 1;

int largepagesupport = 0;
extern uint_t page_create_new;
extern uint_t page_create_exists;
extern uint_t page_create_putbacks;
/*
 * Allow users to disable the kernel's use of SSE.
 */
extern int use_sse_pagecopy, use_sse_pagezero;

/*
 * combined memory ranges from mnode and memranges[] to manage single
 * mnode/mtype dimension in the page lists.
 */
typedef struct {
	pfn_t	mnr_pfnlo;
	pfn_t	mnr_pfnhi;
	int	mnr_mnode;
	int	mnr_memrange;		/* index into memranges[] */
	int	mnr_next;		/* next lower PA mnoderange */
	int	mnr_exists;
	/* maintain page list stats */
	pgcnt_t	mnr_mt_clpgcnt;		/* cache list cnt */
	pgcnt_t	mnr_mt_flpgcnt[MMU_PAGE_SIZES];	/* free list cnt per szc */
	pgcnt_t	mnr_mt_totcnt;		/* sum of cache and free lists */
#ifdef DEBUG
	struct mnr_mts {		/* mnode/mtype szc stats */
		pgcnt_t	mnr_mts_pgcnt;
		int	mnr_mts_colors;
		pgcnt_t *mnr_mtsc_pgcnt;
	} 	*mnr_mts;
#endif
} mnoderange_t;

#define	MEMRANGEHI(mtype)						\
	((mtype > 0) ? memranges[mtype - 1] - 1: physmax)
#define	MEMRANGELO(mtype)	(memranges[mtype])

#define	MTYPE_FREEMEM(mt)	(mnoderanges[mt].mnr_mt_totcnt)

/*
 * As the PC architecture evolved memory up was clumped into several
 * ranges for various historical I/O devices to do DMA.
 * < 16Meg - ISA bus
 * < 2Gig - ???
 * < 4Gig - PCI bus or drivers that don't understand PAE mode
 *
 * These are listed in reverse order, so that we can skip over unused
 * ranges on machines with small memories.
 *
 * For now under the Hypervisor, we'll only ever have one memrange.
 */
#define	PFN_4GIG	0x100000
#define	PFN_16MEG	0x1000
/* Indices into the memory range (arch_memranges) array. */
#define	MRI_4G		0
#define	MRI_2G		1
#define	MRI_16M		2
#define	MRI_0		3
static pfn_t arch_memranges[NUM_MEM_RANGES] = {
    PFN_4GIG,	/* pfn range for 4G and above */
    0x80000,	/* pfn range for 2G-4G */
    PFN_16MEG,	/* pfn range for 16M-2G */
    0x00000,	/* pfn range for 0-16M */
};
pfn_t *memranges = &arch_memranges[0];
int nranges = NUM_MEM_RANGES;

/*
 * This combines mem_node_config and memranges into one data
 * structure to be used for page list management.
 */
mnoderange_t	*mnoderanges;
int		mnoderangecnt;
int		mtype4g;
int		mtype16m;
int		mtypetop;	/* index of highest pfn'ed mnoderange */

/*
 * 4g memory management variables for systems with more than 4g of memory:
 *
 * physical memory below 4g is required for 32bit dma devices and, currently,
 * for kmem memory. On systems with more than 4g of memory, the pool of memory
 * below 4g can be depleted without any paging activity given that there is
 * likely to be sufficient memory above 4g.
 *
 * physmax4g is set true if the largest pfn is over 4g. The rest of the
 * 4g memory management code is enabled only when physmax4g is true.
 *
 * maxmem4g is the count of the maximum number of pages on the page lists
 * with physical addresses below 4g. It can be a lot less then 4g given that
 * BIOS may reserve large chunks of space below 4g for hot plug pci devices,
 * agp aperture etc.
 *
 * freemem4g maintains the count of the number of available pages on the
 * page lists with physical addresses below 4g.
 *
 * DESFREE4G specifies the desired amount of below 4g memory. It defaults to
 * 6% (desfree4gshift = 4) of maxmem4g.
 *
 * RESTRICT4G_ALLOC returns true if freemem4g falls below DESFREE4G
 * and the amount of physical memory above 4g is greater than freemem4g.
 * In this case, page_get_* routines will restrict below 4g allocations
 * for requests that don't specifically require it.
 */

#define	DESFREE4G	(maxmem4g >> desfree4gshift)

#define	RESTRICT4G_ALLOC					\
	(physmax4g && (freemem4g < DESFREE4G) && ((freemem4g << 1) < freemem))

static pgcnt_t	maxmem4g;
static pgcnt_t	freemem4g;
static int	physmax4g;
static int	desfree4gshift = 4;	/* maxmem4g shift to derive DESFREE4G */

/*
 * 16m memory management:
 *
 * reserve some amount of physical memory below 16m for legacy devices.
 *
 * RESTRICT16M_ALLOC returns true if an there are sufficient free pages above
 * 16m or if the 16m pool drops below DESFREE16M.
 *
 * In this case, general page allocations via page_get_{free,cache}list
 * routines will be restricted from allocating from the 16m pool. Allocations
 * that require specific pfn ranges (page_get_anylist) and PG_PANIC allocations
 * are not restricted.
 */

#define	FREEMEM16M	MTYPE_FREEMEM(mtype16m)
#define	DESFREE16M	desfree16m
#define	RESTRICT16M_ALLOC(freemem, pgcnt, flags)		\
	((freemem != 0) && ((flags & PG_PANIC) == 0) &&		\
	    ((freemem >= (FREEMEM16M)) ||			\
	    (FREEMEM16M  < (DESFREE16M + pgcnt))))

static pgcnt_t	desfree16m = 0x380;

/*
 * This can be patched via /etc/system to allow old non-PAE aware device
 * drivers to use kmem_alloc'd memory on 32 bit systems with > 4Gig RAM.
 */
int restricted_kmemalloc = 0;

#ifdef VM_STATS
struct {
	ulong_t	pga_alloc;
	ulong_t	pga_notfullrange;
	ulong_t	pga_nulldmaattr;
	ulong_t	pga_allocok;
	ulong_t	pga_allocfailed;
	ulong_t	pgma_alloc;
	ulong_t	pgma_allocok;
	ulong_t	pgma_allocfailed;
	ulong_t	pgma_allocempty;
} pga_vmstats;
#endif

uint_t mmu_page_sizes;

/* How many page sizes the users can see */
uint_t mmu_exported_page_sizes;

/* page sizes that legacy applications can see */
uint_t mmu_legacy_page_sizes;

/*
 * Number of pages in 1 GB.  Don't enable automatic large pages if we have
 * fewer than this many pages.
 */
pgcnt_t shm_lpg_min_physmem = 1 << (30 - MMU_PAGESHIFT);
pgcnt_t privm_lpg_min_physmem = 1 << (30 - MMU_PAGESHIFT);

/*
 * Maximum and default segment size tunables for user private
 * and shared anon memory, and user text and initialized data.
 * These can be patched via /etc/system to allow large pages
 * to be used for mapping application private and shared anon memory.
 */
size_t mcntl0_lpsize = MMU_PAGESIZE;
size_t max_uheap_lpsize = MMU_PAGESIZE;
size_t default_uheap_lpsize = MMU_PAGESIZE;
size_t max_ustack_lpsize = MMU_PAGESIZE;
size_t default_ustack_lpsize = MMU_PAGESIZE;
size_t max_privmap_lpsize = MMU_PAGESIZE;
size_t max_uidata_lpsize = MMU_PAGESIZE;
size_t max_utext_lpsize = MMU_PAGESIZE;
size_t max_shm_lpsize = MMU_PAGESIZE;


/*
 * initialized by page_coloring_init().
 */
uint_t	page_colors;
uint_t	page_colors_mask;
uint_t	page_coloring_shift;
int	cpu_page_colors;
static uint_t	l2_colors;

/*
 * Page freelists and cachelists are dynamically allocated once mnoderangecnt
 * and page_colors are calculated from the l2 cache n-way set size.  Within a
 * mnode range, the page freelist and cachelist are hashed into bins based on
 * color. This makes it easier to search for a page within a specific memory
 * range.
 */
#define	PAGE_COLORS_MIN	16

page_t ****page_freelists;
page_t ***page_cachelists;


/*
 * Used by page layer to know about page sizes
 */
hw_pagesize_t hw_page_array[MAX_NUM_LEVEL + 1];

kmutex_t	*fpc_mutex[NPC_MUTEX];
kmutex_t	*cpc_mutex[NPC_MUTEX];

/* Lock to protect mnoderanges array for memory DR operations. */
static kmutex_t mnoderange_lock;

/*
 * Only let one thread at a time try to coalesce large pages, to
 * prevent them from working against each other.
 */
static kmutex_t	contig_lock;
#define	CONTIG_LOCK()	mutex_enter(&contig_lock);
#define	CONTIG_UNLOCK()	mutex_exit(&contig_lock);

#define	PFN_16M		(mmu_btop((uint64_t)0x1000000))

/*
 * Return the optimum page size for a given mapping
 */
/*ARGSUSED*/
size_t
map_pgsz(int maptype, struct proc *p, caddr_t addr, size_t len, int memcntl)
{
	level_t l = 0;
	size_t pgsz = MMU_PAGESIZE;
	size_t max_lpsize;
	uint_t mszc;

	ASSERT(maptype != MAPPGSZ_VA);

	if (maptype != MAPPGSZ_ISM && physmem < privm_lpg_min_physmem) {
		return (MMU_PAGESIZE);
	}

	switch (maptype) {
	case MAPPGSZ_HEAP:
	case MAPPGSZ_STK:
		max_lpsize = memcntl ? mcntl0_lpsize : (maptype ==
		    MAPPGSZ_HEAP ? max_uheap_lpsize : max_ustack_lpsize);
		if (max_lpsize == MMU_PAGESIZE) {
			return (MMU_PAGESIZE);
		}
		if (len == 0) {
			len = (maptype == MAPPGSZ_HEAP) ? p->p_brkbase +
			    p->p_brksize - p->p_bssbase : p->p_stksize;
		}
		len = (maptype == MAPPGSZ_HEAP) ? MAX(len,
		    default_uheap_lpsize) : MAX(len, default_ustack_lpsize);

		/*
		 * use the pages size that best fits len
		 */
		for (l = mmu.umax_page_level; l > 0; --l) {
			if (LEVEL_SIZE(l) > max_lpsize || len < LEVEL_SIZE(l)) {
				continue;
			} else {
				pgsz = LEVEL_SIZE(l);
			}
			break;
		}

		mszc = (maptype == MAPPGSZ_HEAP ? p->p_brkpageszc :
		    p->p_stkpageszc);
		if (addr == 0 && (pgsz < hw_page_array[mszc].hp_size)) {
			pgsz = hw_page_array[mszc].hp_size;
		}
		return (pgsz);

	case MAPPGSZ_ISM:
		for (l = mmu.umax_page_level; l > 0; --l) {
			if (len >= LEVEL_SIZE(l))
				return (LEVEL_SIZE(l));
		}
		return (LEVEL_SIZE(0));
	}
	return (pgsz);
}

static uint_t
map_szcvec(caddr_t addr, size_t size, uintptr_t off, size_t max_lpsize,
    size_t min_physmem)
{
	caddr_t eaddr = addr + size;
	uint_t szcvec = 0;
	caddr_t raddr;
	caddr_t readdr;
	size_t	pgsz;
	int i;

	if (physmem < min_physmem || max_lpsize <= MMU_PAGESIZE) {
		return (0);
	}

	for (i = mmu_exported_page_sizes - 1; i > 0; i--) {
		pgsz = page_get_pagesize(i);
		if (pgsz > max_lpsize) {
			continue;
		}
		raddr = (caddr_t)P2ROUNDUP((uintptr_t)addr, pgsz);
		readdr = (caddr_t)P2ALIGN((uintptr_t)eaddr, pgsz);
		if (raddr < addr || raddr >= readdr) {
			continue;
		}
		if (P2PHASE((uintptr_t)addr ^ off, pgsz)) {
			continue;
		}
		/*
		 * Set szcvec to the remaining page sizes.
		 */
		szcvec = ((1 << (i + 1)) - 1) & ~1;
		break;
	}
	return (szcvec);
}

/*
 * Return a bit vector of large page size codes that
 * can be used to map [addr, addr + len) region.
 */
/*ARGSUSED*/
uint_t
map_pgszcvec(caddr_t addr, size_t size, uintptr_t off, int flags, int type,
    int memcntl)
{
	size_t max_lpsize = mcntl0_lpsize;

	if (mmu.max_page_level == 0)
		return (0);

	if (flags & MAP_TEXT) {
		if (!memcntl)
			max_lpsize = max_utext_lpsize;
		return (map_szcvec(addr, size, off, max_lpsize,
		    shm_lpg_min_physmem));

	} else if (flags & MAP_INITDATA) {
		if (!memcntl)
			max_lpsize = max_uidata_lpsize;
		return (map_szcvec(addr, size, off, max_lpsize,
		    privm_lpg_min_physmem));

	} else if (type == MAPPGSZC_SHM) {
		if (!memcntl)
			max_lpsize = max_shm_lpsize;
		return (map_szcvec(addr, size, off, max_lpsize,
		    shm_lpg_min_physmem));

	} else if (type == MAPPGSZC_HEAP) {
		if (!memcntl)
			max_lpsize = max_uheap_lpsize;
		return (map_szcvec(addr, size, off, max_lpsize,
		    privm_lpg_min_physmem));

	} else if (type == MAPPGSZC_STACK) {
		if (!memcntl)
			max_lpsize = max_ustack_lpsize;
		return (map_szcvec(addr, size, off, max_lpsize,
		    privm_lpg_min_physmem));

	} else {
		if (!memcntl)
			max_lpsize = max_privmap_lpsize;
		return (map_szcvec(addr, size, off, max_lpsize,
		    privm_lpg_min_physmem));
	}
}

/*
 * Handle a pagefault.
 */
faultcode_t
pagefault(
	caddr_t addr,
	enum fault_type type,
	enum seg_rw rw,
	int iskernel)
{
	struct as *as;
	struct hat *hat;
	struct proc *p;
	kthread_t *t;
	faultcode_t res;
	caddr_t base;
	size_t len;
	int err;
	int mapped_red;
	uintptr_t ea;

	ASSERT_STACK_ALIGNED();

	if (INVALID_VADDR(addr))
		return (FC_NOMAP);

	mapped_red = segkp_map_red();

	if (iskernel) {
		as = &kas;
		hat = as->a_hat;
	} else {
		t = curthread;
		p = ttoproc(t);
		as = p->p_as;
		hat = as->a_hat;
	}

	/*
	 * Dispatch pagefault.
	 */
	res = as_fault(hat, as, addr, 1, type, rw);

	/*
	 * If this isn't a potential unmapped hole in the user's
	 * UNIX data or stack segments, just return status info.
	 */
	if (res != FC_NOMAP || iskernel)
		goto out;

	/*
	 * Check to see if we happened to faulted on a currently unmapped
	 * part of the UNIX data or stack segments.  If so, create a zfod
	 * mapping there and then try calling the fault routine again.
	 */
	base = p->p_brkbase;
	len = p->p_brksize;

	if (addr < base || addr >= base + len) {		/* data seg? */
		base = (caddr_t)p->p_usrstack - p->p_stksize;
		len = p->p_stksize;
		if (addr < base || addr >= p->p_usrstack) {	/* stack seg? */
			/* not in either UNIX data or stack segments */
			res = FC_NOMAP;
			goto out;
		}
	}

	/*
	 * the rest of this function implements a 3.X 4.X 5.X compatibility
	 * This code is probably not needed anymore
	 */
	if (p->p_model == DATAMODEL_ILP32) {

		/* expand the gap to the page boundaries on each side */
		ea = P2ROUNDUP((uintptr_t)base + len, MMU_PAGESIZE);
		base = (caddr_t)P2ALIGN((uintptr_t)base, MMU_PAGESIZE);
		len = ea - (uintptr_t)base;

		as_rangelock(as);
		if (as_gap(as, MMU_PAGESIZE, &base, &len, AH_CONTAIN, addr) ==
		    0) {
			err = as_map(as, base, len, segvn_create, zfod_argsp);
			as_rangeunlock(as);
			if (err) {
				res = FC_MAKE_ERR(err);
				goto out;
			}
		} else {
			/*
			 * This page is already mapped by another thread after
			 * we returned from as_fault() above.  We just fall
			 * through as_fault() below.
			 */
			as_rangeunlock(as);
		}

		res = as_fault(hat, as, addr, 1, F_INVAL, rw);
	}

out:
	if (mapped_red)
		segkp_unmap_red();

	return (res);
}

void
map_addr(caddr_t *addrp, size_t len, offset_t off, int vacalign, uint_t flags)
{
	struct proc *p = curproc;
	caddr_t userlimit = (flags & _MAP_LOW32) ?
	    (caddr_t)_userlimit32 : p->p_as->a_userlimit;

	map_addr_proc(addrp, len, off, vacalign, userlimit, curproc, flags);
}

/*ARGSUSED*/
int
map_addr_vacalign_check(caddr_t addr, u_offset_t off)
{
	return (0);
}

/*
 * map_addr_proc() is the routine called when the system is to
 * choose an address for the user.  We will pick an address
 * range which is the highest available below userlimit.
 *
 * Every mapping will have a redzone of a single page on either side of
 * the request. This is done to leave one page unmapped between segments.
 * This is not required, but it's useful for the user because if their
 * program strays across a segment boundary, it will catch a fault
 * immediately making debugging a little easier.  Currently the redzone
 * is mandatory.
 *
 * addrp is a value/result parameter.
 *	On input it is a hint from the user to be used in a completely
 *	machine dependent fashion.  We decide to completely ignore this hint.
 *	If MAP_ALIGN was specified, addrp contains the minimal alignment, which
 *	must be some "power of two" multiple of pagesize.
 *
 *	On output it is NULL if no address can be found in the current
 *	processes address space or else an address that is currently
 *	not mapped for len bytes with a page of red zone on either side.
 *
 *	vacalign is not needed on x86 (it's for viturally addressed caches)
 */
/*ARGSUSED*/
void
map_addr_proc(
	caddr_t *addrp,
	size_t len,
	offset_t off,
	int vacalign,
	caddr_t userlimit,
	struct proc *p,
	uint_t flags)
{
	struct as *as = p->p_as;
	caddr_t addr;
	caddr_t base;
	size_t slen;
	size_t align_amount;

	ASSERT32(userlimit == as->a_userlimit);

	base = p->p_brkbase;
#if defined(__amd64)
	/*
	 * XX64 Yes, this needs more work.
	 */
	if (p->p_model == DATAMODEL_NATIVE) {
		if (userlimit < as->a_userlimit) {
			/*
			 * This happens when a program wants to map
			 * something in a range that's accessible to a
			 * program in a smaller address space.  For example,
			 * a 64-bit program calling mmap32(2) to guarantee
			 * that the returned address is below 4Gbytes.
			 */
			ASSERT((uintptr_t)userlimit < ADDRESS_C(0xffffffff));

			if (userlimit > base)
				slen = userlimit - base;
			else {
				*addrp = NULL;
				return;
			}
		} else {
			/*
			 * XX64 This layout is probably wrong .. but in
			 * the event we make the amd64 address space look
			 * like sparcv9 i.e. with the stack -above- the
			 * heap, this bit of code might even be correct.
			 */
			slen = p->p_usrstack - base -
			    ((p->p_stk_ctl + PAGEOFFSET) & PAGEMASK);
		}
	} else
#endif
		slen = userlimit - base;

	/* Make len be a multiple of PAGESIZE */
	len = (len + PAGEOFFSET) & PAGEMASK;

	/*
	 * figure out what the alignment should be
	 *
	 * XX64 -- is there an ELF_AMD64_MAXPGSZ or is it the same????
	 */
	if (len <= ELF_386_MAXPGSZ) {
		/*
		 * Align virtual addresses to ensure that ELF shared libraries
		 * are mapped with the appropriate alignment constraints by
		 * the run-time linker.
		 */
		align_amount = ELF_386_MAXPGSZ;
	} else {
		/*
		 * For 32-bit processes, only those which have specified
		 * MAP_ALIGN and an addr will be aligned on a larger page size.
		 * Not doing so can potentially waste up to 1G of process
		 * address space.
		 */
		int lvl = (p->p_model == DATAMODEL_ILP32) ? 1 :
		    mmu.umax_page_level;

		while (lvl && len < LEVEL_SIZE(lvl))
			--lvl;

		align_amount = LEVEL_SIZE(lvl);
	}
	if ((flags & MAP_ALIGN) && ((uintptr_t)*addrp > align_amount))
		align_amount = (uintptr_t)*addrp;

	ASSERT(ISP2(align_amount));
	ASSERT(align_amount == 0 || align_amount >= PAGESIZE);

	off = off & (align_amount - 1);
	/*
	 * Look for a large enough hole starting below userlimit.
	 * After finding it, use the upper part.
	 */
	if (as_gap_aligned(as, len, &base, &slen, AH_HI, NULL, align_amount,
	    PAGESIZE, off) == 0) {
		caddr_t as_addr;

		/*
		 * addr is the highest possible address to use since we have
		 * a PAGESIZE redzone at the beginning and end.
		 */
		addr = base + slen - (PAGESIZE + len);
		as_addr = addr;
		/*
		 * Round address DOWN to the alignment amount and
		 * add the offset in.
		 * If addr is greater than as_addr, len would not be large
		 * enough to include the redzone, so we must adjust down
		 * by the alignment amount.
		 */
		addr = (caddr_t)((uintptr_t)addr & (~(align_amount - 1)));
		addr += (uintptr_t)off;
		if (addr > as_addr) {
			addr -= align_amount;
		}

		ASSERT(addr > base);
		ASSERT(addr + len < base + slen);
		ASSERT(((uintptr_t)addr & (align_amount - 1)) ==
		    ((uintptr_t)(off)));
		*addrp = addr;
	} else {
		*addrp = NULL;	/* no more virtual space */
	}
}

int valid_va_range_aligned_wraparound;

/*
 * Determine whether [*basep, *basep + *lenp) contains a mappable range of
 * addresses at least "minlen" long, where the base of the range is at "off"
 * phase from an "align" boundary and there is space for a "redzone"-sized
 * redzone on either side of the range.  On success, 1 is returned and *basep
 * and *lenp are adjusted to describe the acceptable range (including
 * the redzone).  On failure, 0 is returned.
 */
/*ARGSUSED3*/
int
valid_va_range_aligned(caddr_t *basep, size_t *lenp, size_t minlen, int dir,
    size_t align, size_t redzone, size_t off)
{
	uintptr_t hi, lo;
	size_t tot_len;

	ASSERT(align == 0 ? off == 0 : off < align);
	ASSERT(ISP2(align));
	ASSERT(align == 0 || align >= PAGESIZE);

	lo = (uintptr_t)*basep;
	hi = lo + *lenp;
	tot_len = minlen + 2 * redzone; /* need at least this much space */

	/*
	 * If hi rolled over the top, try cutting back.
	 */
	if (hi < lo) {
		*lenp = 0UL - lo - 1UL;
		/* See if this really happens. If so, then we figure out why */
		valid_va_range_aligned_wraparound++;
		hi = lo + *lenp;
	}
	if (*lenp < tot_len) {
		return (0);
	}

#if defined(__amd64)
	/*
	 * Deal with a possible hole in the address range between
	 * hole_start and hole_end that should never be mapped.
	 */
	if (lo < hole_start) {
		if (hi > hole_start) {
			if (hi < hole_end) {
				hi = hole_start;
			} else {
				/* lo < hole_start && hi >= hole_end */
				if (dir == AH_LO) {
					/*
					 * prefer lowest range
					 */
					if (hole_start - lo >= tot_len)
						hi = hole_start;
					else if (hi - hole_end >= tot_len)
						lo = hole_end;
					else
						return (0);
				} else {
					/*
					 * prefer highest range
					 */
					if (hi - hole_end >= tot_len)
						lo = hole_end;
					else if (hole_start - lo >= tot_len)
						hi = hole_start;
					else
						return (0);
				}
			}
		}
	} else {
		/* lo >= hole_start */
		if (hi < hole_end)
			return (0);
		if (lo < hole_end)
			lo = hole_end;
	}
#endif

	if (hi - lo < tot_len)
		return (0);

	if (align > 1) {
		uintptr_t tlo = lo + redzone;
		uintptr_t thi = hi - redzone;
		tlo = (uintptr_t)P2PHASEUP(tlo, align, off);
		if (tlo < lo + redzone) {
			return (0);
		}
		if (thi < tlo || thi - tlo < minlen) {
			return (0);
		}
	}

	*basep = (caddr_t)lo;
	*lenp = hi - lo;
	return (1);
}

/*
 * Determine whether [*basep, *basep + *lenp) contains a mappable range of
 * addresses at least "minlen" long.  On success, 1 is returned and *basep
 * and *lenp are adjusted to describe the acceptable range.  On failure, 0
 * is returned.
 */
int
valid_va_range(caddr_t *basep, size_t *lenp, size_t minlen, int dir)
{
	return (valid_va_range_aligned(basep, lenp, minlen, dir, 0, 0, 0));
}

/*
 * Determine whether [addr, addr+len] are valid user addresses.
 */
/*ARGSUSED*/
int
valid_usr_range(caddr_t addr, size_t len, uint_t prot, struct as *as,
    caddr_t userlimit)
{
	caddr_t eaddr = addr + len;

	if (eaddr <= addr || addr >= userlimit || eaddr > userlimit)
		return (RANGE_BADADDR);

#if defined(__amd64)
	/*
	 * Check for the VA hole
	 */
	if (eaddr > (caddr_t)hole_start && addr < (caddr_t)hole_end)
		return (RANGE_BADADDR);
#endif

	return (RANGE_OKAY);
}

/*
 * Return 1 if the page frame is onboard memory, else 0.
 */
int
pf_is_memory(pfn_t pf)
{
	if (pfn_is_foreign(pf))
		return (0);
	return (address_in_memlist(phys_install, pfn_to_pa(pf), 1));
}

/*
 * return the memrange containing pfn
 */
int
memrange_num(pfn_t pfn)
{
	int n;

	for (n = 0; n < nranges - 1; ++n) {
		if (pfn >= memranges[n])
			break;
	}
	return (n);
}

/*
 * return the mnoderange containing pfn
 */
/*ARGSUSED*/
int
pfn_2_mtype(pfn_t pfn)
{
#if defined(__xpv)
	return (0);
#else
	int	n;

	/* Always start from highest pfn and work our way down */
	for (n = mtypetop; n != -1; n = mnoderanges[n].mnr_next) {
		if (pfn >= mnoderanges[n].mnr_pfnlo) {
			break;
		}
	}
	return (n);
#endif
}

#if !defined(__xpv)
/*
 * is_contigpage_free:
 *	returns a page list of contiguous pages. It minimally has to return
 *	minctg pages. Caller determines minctg based on the scatter-gather
 *	list length.
 *
 *	pfnp is set to the next page frame to search on return.
 */
static page_t *
is_contigpage_free(
	pfn_t *pfnp,
	pgcnt_t *pgcnt,
	pgcnt_t minctg,
	uint64_t pfnseg,
	int iolock)
{
	int	i = 0;
	pfn_t	pfn = *pfnp;
	page_t	*pp;
	page_t	*plist = NULL;

	/*
	 * fail if pfn + minctg crosses a segment boundary.
	 * Adjust for next starting pfn to begin at segment boundary.
	 */

	if (((*pfnp + minctg - 1) & pfnseg) < (*pfnp & pfnseg)) {
		*pfnp = roundup(*pfnp, pfnseg + 1);
		return (NULL);
	}

	do {
retry:
		pp = page_numtopp_nolock(pfn + i);
		if ((pp == NULL) ||
		    (page_trylock(pp, SE_EXCL) == 0)) {
			(*pfnp)++;
			break;
		}
		if (page_pptonum(pp) != pfn + i) {
			page_unlock(pp);
			goto retry;
		}

		if (!(PP_ISFREE(pp))) {
			page_unlock(pp);
			(*pfnp)++;
			break;
		}

		if (!PP_ISAGED(pp)) {
			page_list_sub(pp, PG_CACHE_LIST);
			page_hashout(pp, (kmutex_t *)NULL);
		} else {
			page_list_sub(pp, PG_FREE_LIST);
		}

		if (iolock)
			page_io_lock(pp);
		page_list_concat(&plist, &pp);

		/*
		 * exit loop when pgcnt satisfied or segment boundary reached.
		 */

	} while ((++i < *pgcnt) && ((pfn + i) & pfnseg));

	*pfnp += i;		/* set to next pfn to search */

	if (i >= minctg) {
		*pgcnt -= i;
		return (plist);
	}

	/*
	 * failure: minctg not satisfied.
	 *
	 * if next request crosses segment boundary, set next pfn
	 * to search from the segment boundary.
	 */
	if (((*pfnp + minctg - 1) & pfnseg) < (*pfnp & pfnseg))
		*pfnp = roundup(*pfnp, pfnseg + 1);

	/* clean up any pages already allocated */

	while (plist) {
		pp = plist;
		page_sub(&plist, pp);
		page_list_add(pp, PG_FREE_LIST | PG_LIST_TAIL);
		if (iolock)
			page_io_unlock(pp);
		page_unlock(pp);
	}

	return (NULL);
}
#endif	/* !__xpv */

/*
 * verify that pages being returned from allocator have correct DMA attribute
 */
#ifndef DEBUG
#define	check_dma(a, b, c) (void)(0)
#else
static void
check_dma(ddi_dma_attr_t *dma_attr, page_t *pp, int cnt)
{
	if (dma_attr == NULL)
		return;

	while (cnt-- > 0) {
		if (pa_to_ma(pfn_to_pa(pp->p_pagenum)) <
		    dma_attr->dma_attr_addr_lo)
			panic("PFN (pp=%p) below dma_attr_addr_lo", (void *)pp);
		if (pa_to_ma(pfn_to_pa(pp->p_pagenum)) >=
		    dma_attr->dma_attr_addr_hi)
			panic("PFN (pp=%p) above dma_attr_addr_hi", (void *)pp);
		pp = pp->p_next;
	}
}
#endif

#if !defined(__xpv)
static page_t *
page_get_contigpage(pgcnt_t *pgcnt, ddi_dma_attr_t *mattr, int iolock)
{
	pfn_t		pfn;
	int		sgllen;
	uint64_t	pfnseg;
	pgcnt_t		minctg;
	page_t		*pplist = NULL, *plist;
	uint64_t	lo, hi;
	pgcnt_t		pfnalign = 0;
	static pfn_t	startpfn;
	static pgcnt_t	lastctgcnt;
	uintptr_t	align;

	CONTIG_LOCK();

	if (mattr) {
		lo = mmu_btop((mattr->dma_attr_addr_lo + MMU_PAGEOFFSET));
		hi = mmu_btop(mattr->dma_attr_addr_hi);
		if (hi >= physmax)
			hi = physmax - 1;
		sgllen = mattr->dma_attr_sgllen;
		pfnseg = mmu_btop(mattr->dma_attr_seg);

		align = maxbit(mattr->dma_attr_align, mattr->dma_attr_minxfer);
		if (align > MMU_PAGESIZE)
			pfnalign = mmu_btop(align);

		/*
		 * in order to satisfy the request, must minimally
		 * acquire minctg contiguous pages
		 */
		minctg = howmany(*pgcnt, sgllen);

		ASSERT(hi >= lo);

		/*
		 * start from where last searched if the minctg >= lastctgcnt
		 */
		if (minctg < lastctgcnt || startpfn < lo || startpfn > hi)
			startpfn = lo;
	} else {
		hi = physmax - 1;
		lo = 0;
		sgllen = 1;
		pfnseg = mmu.highest_pfn;
		minctg = *pgcnt;

		if (minctg < lastctgcnt)
			startpfn = lo;
	}
	lastctgcnt = minctg;

	ASSERT(pfnseg + 1 >= (uint64_t)minctg);

	/* conserve 16m memory - start search above 16m when possible */
	if (hi > PFN_16M && startpfn < PFN_16M)
		startpfn = PFN_16M;

	pfn = startpfn;
	if (pfnalign)
		pfn = P2ROUNDUP(pfn, pfnalign);

	while (pfn + minctg - 1 <= hi) {

		plist = is_contigpage_free(&pfn, pgcnt, minctg, pfnseg, iolock);
		if (plist) {
			page_list_concat(&pplist, &plist);
			sgllen--;
			/*
			 * return when contig pages no longer needed
			 */
			if (!*pgcnt || ((*pgcnt <= sgllen) && !pfnalign)) {
				startpfn = pfn;
				CONTIG_UNLOCK();
				check_dma(mattr, pplist, *pgcnt);
				return (pplist);
			}
			minctg = howmany(*pgcnt, sgllen);
		}
		if (pfnalign)
			pfn = P2ROUNDUP(pfn, pfnalign);
	}

	/* cannot find contig pages in specified range */
	if (startpfn == lo) {
		CONTIG_UNLOCK();
		return (NULL);
	}

	/* did not start with lo previously */
	pfn = lo;
	if (pfnalign)
		pfn = P2ROUNDUP(pfn, pfnalign);

	/* allow search to go above startpfn */
	while (pfn < startpfn) {

		plist = is_contigpage_free(&pfn, pgcnt, minctg, pfnseg, iolock);
		if (plist != NULL) {

			page_list_concat(&pplist, &plist);
			sgllen--;

			/*
			 * return when contig pages no longer needed
			 */
			if (!*pgcnt || ((*pgcnt <= sgllen) && !pfnalign)) {
				startpfn = pfn;
				CONTIG_UNLOCK();
				check_dma(mattr, pplist, *pgcnt);
				return (pplist);
			}
			minctg = howmany(*pgcnt, sgllen);
		}
		if (pfnalign)
			pfn = P2ROUNDUP(pfn, pfnalign);
	}
	CONTIG_UNLOCK();
	return (NULL);
}
#endif	/* !__xpv */

/*
 * mnode_range_cnt() calculates the number of memory ranges for mnode and
 * memranges[]. Used to determine the size of page lists and mnoderanges.
 */
int
mnode_range_cnt(int mnode)
{
#if defined(__xpv)
	ASSERT(mnode == 0);
	return (1);
#else	/* __xpv */
	int	mri;
	int	mnrcnt = 0;

	if (mem_node_config[mnode].exists != 0) {
		mri = nranges - 1;

		/* find the memranges index below contained in mnode range */

		while (MEMRANGEHI(mri) < mem_node_config[mnode].physbase)
			mri--;

		/*
		 * increment mnode range counter when memranges or mnode
		 * boundary is reached.
		 */
		while (mri >= 0 &&
		    mem_node_config[mnode].physmax >= MEMRANGELO(mri)) {
			mnrcnt++;
			if (mem_node_config[mnode].physmax > MEMRANGEHI(mri))
				mri--;
			else
				break;
		}
	}
	ASSERT(mnrcnt <= MAX_MNODE_MRANGES);
	return (mnrcnt);
#endif	/* __xpv */
}

/*
 * mnode_range_setup() initializes mnoderanges.
 */
void
mnode_range_setup(mnoderange_t *mnoderanges)
{
	mnoderange_t *mp = mnoderanges;
	int	mnode, mri;
	int	mindex = 0;	/* current index into mnoderanges array */
	int	i, j;
	pfn_t	hipfn;
	int	last, hi;

	for (mnode = 0; mnode < max_mem_nodes; mnode++) {
		if (mem_node_config[mnode].exists == 0)
			continue;

		mri = nranges - 1;

		while (MEMRANGEHI(mri) < mem_node_config[mnode].physbase)
			mri--;

		while (mri >= 0 && mem_node_config[mnode].physmax >=
		    MEMRANGELO(mri)) {
			mnoderanges->mnr_pfnlo = MAX(MEMRANGELO(mri),
			    mem_node_config[mnode].physbase);
			mnoderanges->mnr_pfnhi = MIN(MEMRANGEHI(mri),
			    mem_node_config[mnode].physmax);
			mnoderanges->mnr_mnode = mnode;
			mnoderanges->mnr_memrange = mri;
			mnoderanges->mnr_exists = 1;
			mnoderanges++;
			mindex++;
			if (mem_node_config[mnode].physmax > MEMRANGEHI(mri))
				mri--;
			else
				break;
		}
	}

	/*
	 * For now do a simple sort of the mnoderanges array to fill in
	 * the mnr_next fields.  Since mindex is expected to be relatively
	 * small, using a simple O(N^2) algorithm.
	 */
	for (i = 0; i < mindex; i++) {
		if (mp[i].mnr_pfnlo == 0)	/* find lowest */
			break;
	}
	ASSERT(i < mindex);
	last = i;
	mtype16m = last;
	mp[last].mnr_next = -1;
	for (i = 0; i < mindex - 1; i++) {
		hipfn = (pfn_t)(-1);
		hi = -1;
		/* find next highest mnode range */
		for (j = 0; j < mindex; j++) {
			if (mp[j].mnr_pfnlo > mp[last].mnr_pfnlo &&
			    mp[j].mnr_pfnlo < hipfn) {
				hipfn = mp[j].mnr_pfnlo;
				hi = j;
			}
		}
		mp[hi].mnr_next = last;
		last = hi;
	}
	mtypetop = last;
}

#ifndef	__xpv
/*
 * Update mnoderanges for memory hot-add DR operations.
 */
static void
mnode_range_add(int mnode)
{
	int	*prev;
	int	n, mri;
	pfn_t	start, end;
	extern	void membar_sync(void);

	ASSERT(0 <= mnode && mnode < max_mem_nodes);
	ASSERT(mem_node_config[mnode].exists);
	start = mem_node_config[mnode].physbase;
	end = mem_node_config[mnode].physmax;
	ASSERT(start <= end);
	mutex_enter(&mnoderange_lock);

#ifdef	DEBUG
	/* Check whether it interleaves with other memory nodes. */
	for (n = mtypetop; n != -1; n = mnoderanges[n].mnr_next) {
		ASSERT(mnoderanges[n].mnr_exists);
		if (mnoderanges[n].mnr_mnode == mnode)
			continue;
		ASSERT(start > mnoderanges[n].mnr_pfnhi ||
		    end < mnoderanges[n].mnr_pfnlo);
	}
#endif	/* DEBUG */

	mri = nranges - 1;
	while (MEMRANGEHI(mri) < mem_node_config[mnode].physbase)
		mri--;
	while (mri >= 0 && mem_node_config[mnode].physmax >= MEMRANGELO(mri)) {
		/* Check whether mtype already exists. */
		for (n = mtypetop; n != -1; n = mnoderanges[n].mnr_next) {
			if (mnoderanges[n].mnr_mnode == mnode &&
			    mnoderanges[n].mnr_memrange == mri) {
				mnoderanges[n].mnr_pfnlo = MAX(MEMRANGELO(mri),
				    start);
				mnoderanges[n].mnr_pfnhi = MIN(MEMRANGEHI(mri),
				    end);
				break;
			}
		}

		/* Add a new entry if it doesn't exist yet. */
		if (n == -1) {
			/* Try to find an unused entry in mnoderanges array. */
			for (n = 0; n < mnoderangecnt; n++) {
				if (mnoderanges[n].mnr_exists == 0)
					break;
			}
			ASSERT(n < mnoderangecnt);
			mnoderanges[n].mnr_pfnlo = MAX(MEMRANGELO(mri), start);
			mnoderanges[n].mnr_pfnhi = MIN(MEMRANGEHI(mri), end);
			mnoderanges[n].mnr_mnode = mnode;
			mnoderanges[n].mnr_memrange = mri;
			mnoderanges[n].mnr_exists = 1;
			/* Page 0 should always be present. */
			for (prev = &mtypetop;
			    mnoderanges[*prev].mnr_pfnlo > start;
			    prev = &mnoderanges[*prev].mnr_next) {
				ASSERT(mnoderanges[*prev].mnr_next >= 0);
				ASSERT(mnoderanges[*prev].mnr_pfnlo > end);
			}
			mnoderanges[n].mnr_next = *prev;
			membar_sync();
			*prev = n;
		}

		if (mem_node_config[mnode].physmax > MEMRANGEHI(mri))
			mri--;
		else
			break;
	}

	mutex_exit(&mnoderange_lock);
}

/*
 * Update mnoderanges for memory hot-removal DR operations.
 */
static void
mnode_range_del(int mnode)
{
	_NOTE(ARGUNUSED(mnode));
	ASSERT(0 <= mnode && mnode < max_mem_nodes);
	/* TODO: support deletion operation. */
	ASSERT(0);
}

void
plat_slice_add(pfn_t start, pfn_t end)
{
	mem_node_add_slice(start, end);
	if (plat_dr_enabled()) {
		mnode_range_add(PFN_2_MEM_NODE(start));
	}
}

void
plat_slice_del(pfn_t start, pfn_t end)
{
	ASSERT(PFN_2_MEM_NODE(start) == PFN_2_MEM_NODE(end));
	ASSERT(plat_dr_enabled());
	mnode_range_del(PFN_2_MEM_NODE(start));
	mem_node_del_slice(start, end);
}
#endif	/* __xpv */

/*ARGSUSED*/
int
mtype_init(vnode_t *vp, caddr_t vaddr, uint_t *flags, size_t pgsz)
{
	int mtype = mtypetop;

#if !defined(__xpv)
#if defined(__i386)
	/*
	 * set the mtype range
	 * - kmem requests need to be below 4g if restricted_kmemalloc is set.
	 * - for non kmem requests, set range to above 4g if memory below 4g
	 * runs low.
	 */
	if (restricted_kmemalloc && VN_ISKAS(vp) &&
	    (caddr_t)(vaddr) >= kernelheap &&
	    (caddr_t)(vaddr) < ekernelheap) {
		ASSERT(physmax4g);
		mtype = mtype4g;
		if (RESTRICT16M_ALLOC(freemem4g - btop(pgsz),
		    btop(pgsz), *flags)) {
			*flags |= PGI_MT_RANGE16M;
		} else {
			VM_STAT_ADD(vmm_vmstats.unrestrict16mcnt);
			VM_STAT_COND_ADD((*flags & PG_PANIC),
			    vmm_vmstats.pgpanicalloc);
			*flags |= PGI_MT_RANGE0;
		}
		return (mtype);
	}
#endif	/* __i386 */

	if (RESTRICT4G_ALLOC) {
		VM_STAT_ADD(vmm_vmstats.restrict4gcnt);
		/* here only for > 4g systems */
		*flags |= PGI_MT_RANGE4G;
	} else if (RESTRICT16M_ALLOC(freemem, btop(pgsz), *flags)) {
		*flags |= PGI_MT_RANGE16M;
	} else {
		VM_STAT_ADD(vmm_vmstats.unrestrict16mcnt);
		VM_STAT_COND_ADD((*flags & PG_PANIC), vmm_vmstats.pgpanicalloc);
		*flags |= PGI_MT_RANGE0;
	}
#endif /* !__xpv */
	return (mtype);
}


/* mtype init for page_get_replacement_page */
/*ARGSUSED*/
int
mtype_pgr_init(int *flags, page_t *pp, int mnode, pgcnt_t pgcnt)
{
	int mtype = mtypetop;
#if !defined(__xpv)
	if (RESTRICT16M_ALLOC(freemem, pgcnt, *flags)) {
		*flags |= PGI_MT_RANGE16M;
	} else {
		VM_STAT_ADD(vmm_vmstats.unrestrict16mcnt);
		*flags |= PGI_MT_RANGE0;
	}
#endif
	return (mtype);
}

/*
 * Determine if the mnode range specified in mtype contains memory belonging
 * to memory node mnode.  If flags & PGI_MT_RANGE is set then mtype contains
 * the range from high pfn to 0, 16m or 4g.
 *
 * Return first mnode range type index found otherwise return -1 if none found.
 */
int
mtype_func(int mnode, int mtype, uint_t flags)
{
	if (flags & PGI_MT_RANGE) {
		int	mnr_lim = MRI_0;

		if (flags & PGI_MT_NEXT) {
			mtype = mnoderanges[mtype].mnr_next;
		}
		if (flags & PGI_MT_RANGE4G)
			mnr_lim = MRI_4G;	/* exclude 0-4g range */
		else if (flags & PGI_MT_RANGE16M)
			mnr_lim = MRI_16M;	/* exclude 0-16m range */
		while (mtype != -1 &&
		    mnoderanges[mtype].mnr_memrange <= mnr_lim) {
			if (mnoderanges[mtype].mnr_mnode == mnode)
				return (mtype);
			mtype = mnoderanges[mtype].mnr_next;
		}
	} else if (mnoderanges[mtype].mnr_mnode == mnode) {
		return (mtype);
	}
	return (-1);
}

/*
 * Update the page list max counts with the pfn range specified by the
 * input parameters.
 */
void
mtype_modify_max(pfn_t startpfn, long cnt)
{
	int		mtype;
	pgcnt_t		inc;
	spgcnt_t	scnt = (spgcnt_t)(cnt);
	pgcnt_t		acnt = ABS(scnt);
	pfn_t		endpfn = startpfn + acnt;
	pfn_t		pfn, lo;

	if (!physmax4g)
		return;

	mtype = mtypetop;
	for (pfn = endpfn; pfn > startpfn; ) {
		ASSERT(mtype != -1);
		lo = mnoderanges[mtype].mnr_pfnlo;
		if (pfn > lo) {
			if (startpfn >= lo) {
				inc = pfn - startpfn;
			} else {
				inc = pfn - lo;
			}
			if (mnoderanges[mtype].mnr_memrange != MRI_4G) {
				if (scnt > 0)
					maxmem4g += inc;
				else
					maxmem4g -= inc;
			}
			pfn -= inc;
		}
		mtype = mnoderanges[mtype].mnr_next;
	}
}

int
mtype_2_mrange(int mtype)
{
	return (mnoderanges[mtype].mnr_memrange);
}

void
mnodetype_2_pfn(int mnode, int mtype, pfn_t *pfnlo, pfn_t *pfnhi)
{
	_NOTE(ARGUNUSED(mnode));
	ASSERT(mnoderanges[mtype].mnr_mnode == mnode);
	*pfnlo = mnoderanges[mtype].mnr_pfnlo;
	*pfnhi = mnoderanges[mtype].mnr_pfnhi;
}

size_t
plcnt_sz(size_t ctrs_sz)
{
#ifdef DEBUG
	int	szc, colors;

	ctrs_sz += mnoderangecnt * sizeof (struct mnr_mts) * mmu_page_sizes;
	for (szc = 0; szc < mmu_page_sizes; szc++) {
		colors = page_get_pagecolors(szc);
		ctrs_sz += mnoderangecnt * sizeof (pgcnt_t) * colors;
	}
#endif
	return (ctrs_sz);
}

caddr_t
plcnt_init(caddr_t addr)
{
#ifdef DEBUG
	int	mt, szc, colors;

	for (mt = 0; mt < mnoderangecnt; mt++) {
		mnoderanges[mt].mnr_mts = (struct mnr_mts *)addr;
		addr += (sizeof (struct mnr_mts) * mmu_page_sizes);
		for (szc = 0; szc < mmu_page_sizes; szc++) {
			colors = page_get_pagecolors(szc);
			mnoderanges[mt].mnr_mts[szc].mnr_mts_colors = colors;
			mnoderanges[mt].mnr_mts[szc].mnr_mtsc_pgcnt =
			    (pgcnt_t *)addr;
			addr += (sizeof (pgcnt_t) * colors);
		}
	}
#endif
	return (addr);
}

void
plcnt_inc_dec(page_t *pp, int mtype, int szc, long cnt, int flags)
{
	_NOTE(ARGUNUSED(pp));
#ifdef DEBUG
	int	bin = PP_2_BIN(pp);

	atomic_add_long(&mnoderanges[mtype].mnr_mts[szc].mnr_mts_pgcnt, cnt);
	atomic_add_long(&mnoderanges[mtype].mnr_mts[szc].mnr_mtsc_pgcnt[bin],
	    cnt);
#endif
	ASSERT(mtype == PP_2_MTYPE(pp));
	if (physmax4g && mnoderanges[mtype].mnr_memrange != MRI_4G)
		atomic_add_long(&freemem4g, cnt);
	if (flags & PG_CACHE_LIST)
		atomic_add_long(&mnoderanges[mtype].mnr_mt_clpgcnt, cnt);
	else
		atomic_add_long(&mnoderanges[mtype].mnr_mt_flpgcnt[szc], cnt);
	atomic_add_long(&mnoderanges[mtype].mnr_mt_totcnt, cnt);
}

/*
 * Returns the free page count for mnode
 */
int
mnode_pgcnt(int mnode)
{
	int	mtype = mtypetop;
	int	flags = PGI_MT_RANGE0;
	pgcnt_t	pgcnt = 0;

	mtype = mtype_func(mnode, mtype, flags);

	while (mtype != -1) {
		pgcnt += MTYPE_FREEMEM(mtype);
		mtype = mtype_func(mnode, mtype, flags | PGI_MT_NEXT);
	}
	return (pgcnt);
}

/*
 * Initialize page coloring variables based on the l2 cache parameters.
 * Calculate and return memory needed for page coloring data structures.
 */
size_t
page_coloring_init(uint_t l2_sz, int l2_linesz, int l2_assoc)
{
	_NOTE(ARGUNUSED(l2_linesz));
	size_t	colorsz = 0;
	int	i;
	int	colors;

#if defined(__xpv)
	/*
	 * Hypervisor domains currently don't have any concept of NUMA.
	 * Hence we'll act like there is only 1 memrange.
	 */
	i = memrange_num(1);
#else /* !__xpv */
	/*
	 * Reduce the memory ranges lists if we don't have large amounts
	 * of memory. This avoids searching known empty free lists.
	 * To support memory DR operations, we need to keep memory ranges
	 * for possible memory hot-add operations.
	 */
	if (plat_dr_physmax > physmax)
		i = memrange_num(plat_dr_physmax);
	else
		i = memrange_num(physmax);
#if defined(__i386)
	if (i > MRI_4G)
		restricted_kmemalloc = 0;
#endif
	/* physmax greater than 4g */
	if (i == MRI_4G)
		physmax4g = 1;
#endif /* !__xpv */
	memranges += i;
	nranges -= i;

	ASSERT(mmu_page_sizes <= MMU_PAGE_SIZES);

	ASSERT(ISP2(l2_linesz));
	ASSERT(l2_sz > MMU_PAGESIZE);

	/* l2_assoc is 0 for fully associative l2 cache */
	if (l2_assoc)
		l2_colors = MAX(1, l2_sz / (l2_assoc * MMU_PAGESIZE));
	else
		l2_colors = 1;

	ASSERT(ISP2(l2_colors));

	/* for scalability, configure at least PAGE_COLORS_MIN color bins */
	page_colors = MAX(l2_colors, PAGE_COLORS_MIN);

	/*
	 * cpu_page_colors is non-zero when a page color may be spread across
	 * multiple bins.
	 */
	if (l2_colors < page_colors)
		cpu_page_colors = l2_colors;

	ASSERT(ISP2(page_colors));

	page_colors_mask = page_colors - 1;

	ASSERT(ISP2(CPUSETSIZE()));
	page_coloring_shift = lowbit(CPUSETSIZE());

	/* initialize number of colors per page size */
	for (i = 0; i <= mmu.max_page_level; i++) {
		hw_page_array[i].hp_size = LEVEL_SIZE(i);
		hw_page_array[i].hp_shift = LEVEL_SHIFT(i);
		hw_page_array[i].hp_pgcnt = LEVEL_SIZE(i) >> LEVEL_SHIFT(0);
		hw_page_array[i].hp_colors = (page_colors_mask >>
		    (hw_page_array[i].hp_shift - hw_page_array[0].hp_shift))
		    + 1;
		colorequivszc[i] = 0;
	}

	/*
	 * The value of cpu_page_colors determines if additional color bins
	 * need to be checked for a particular color in the page_get routines.
	 */
	if (cpu_page_colors != 0) {

		int a = lowbit(page_colors) - lowbit(cpu_page_colors);
		ASSERT(a > 0);
		ASSERT(a < 16);

		for (i = 0; i <= mmu.max_page_level; i++) {
			if ((colors = hw_page_array[i].hp_colors) <= 1) {
				colorequivszc[i] = 0;
				continue;
			}
			while ((colors >> a) == 0)
				a--;
			ASSERT(a >= 0);

			/* higher 4 bits encodes color equiv mask */
			colorequivszc[i] = (a << 4);
		}
	}

	/* factor in colorequiv to check additional 'equivalent' bins. */
	if (colorequiv > 1) {

		int a = lowbit(colorequiv) - 1;
		if (a > 15)
			a = 15;

		for (i = 0; i <= mmu.max_page_level; i++) {
			if ((colors = hw_page_array[i].hp_colors) <= 1) {
				continue;
			}
			while ((colors >> a) == 0)
				a--;
			if ((a << 4) > colorequivszc[i]) {
				colorequivszc[i] = (a << 4);
			}
		}
	}

	/* size for mnoderanges */
	for (mnoderangecnt = 0, i = 0; i < max_mem_nodes; i++)
		mnoderangecnt += mnode_range_cnt(i);
	if (plat_dr_support_memory()) {
		/*
		 * Reserve enough space for memory DR operations.
		 * Two extra mnoderanges for possbile fragmentations,
		 * one for the 2G boundary and the other for the 4G boundary.
		 * We don't expect a memory board crossing the 16M boundary
		 * for memory hot-add operations on x86 platforms.
		 */
		mnoderangecnt += 2 + max_mem_nodes - lgrp_plat_node_cnt;
	}
	colorsz = mnoderangecnt * sizeof (mnoderange_t);

	/* size for fpc_mutex and cpc_mutex */
	colorsz += (2 * max_mem_nodes * sizeof (kmutex_t) * NPC_MUTEX);

	/* size of page_freelists */
	colorsz += mnoderangecnt * sizeof (page_t ***);
	colorsz += mnoderangecnt * mmu_page_sizes * sizeof (page_t **);

	for (i = 0; i < mmu_page_sizes; i++) {
		colors = page_get_pagecolors(i);
		colorsz += mnoderangecnt * colors * sizeof (page_t *);
	}

	/* size of page_cachelists */
	colorsz += mnoderangecnt * sizeof (page_t **);
	colorsz += mnoderangecnt * page_colors * sizeof (page_t *);

	return (colorsz);
}

/*
 * Called once at startup to configure page_coloring data structures and
 * does the 1st page_free()/page_freelist_add().
 */
void
page_coloring_setup(caddr_t pcmemaddr)
{
	int	i;
	int	j;
	int	k;
	caddr_t	addr;
	int	colors;

	/*
	 * do page coloring setup
	 */
	addr = pcmemaddr;

	mnoderanges = (mnoderange_t *)addr;
	addr += (mnoderangecnt * sizeof (mnoderange_t));

	mnode_range_setup(mnoderanges);

	if (physmax4g)
		mtype4g = pfn_2_mtype(0xfffff);

	for (k = 0; k < NPC_MUTEX; k++) {
		fpc_mutex[k] = (kmutex_t *)addr;
		addr += (max_mem_nodes * sizeof (kmutex_t));
	}
	for (k = 0; k < NPC_MUTEX; k++) {
		cpc_mutex[k] = (kmutex_t *)addr;
		addr += (max_mem_nodes * sizeof (kmutex_t));
	}
	page_freelists = (page_t ****)addr;
	addr += (mnoderangecnt * sizeof (page_t ***));

	page_cachelists = (page_t ***)addr;
	addr += (mnoderangecnt * sizeof (page_t **));

	for (i = 0; i < mnoderangecnt; i++) {
		page_freelists[i] = (page_t ***)addr;
		addr += (mmu_page_sizes * sizeof (page_t **));

		for (j = 0; j < mmu_page_sizes; j++) {
			colors = page_get_pagecolors(j);
			page_freelists[i][j] = (page_t **)addr;
			addr += (colors * sizeof (page_t *));
		}
		page_cachelists[i] = (page_t **)addr;
		addr += (page_colors * sizeof (page_t *));
	}
}

#if defined(__xpv)
/*
 * Give back 10% of the io_pool pages to the free list.
 * Don't shrink the pool below some absolute minimum.
 */
static void
page_io_pool_shrink()
{
	int retcnt;
	page_t *pp, *pp_first, *pp_last, **curpool;
	mfn_t mfn;
	int bothpools = 0;

	mutex_enter(&io_pool_lock);
	io_pool_shrink_attempts++;	/* should be a kstat? */
	retcnt = io_pool_cnt / 10;
	if (io_pool_cnt - retcnt < io_pool_cnt_min)
		retcnt = io_pool_cnt - io_pool_cnt_min;
	if (retcnt <= 0)
		goto done;
	io_pool_shrinks++;	/* should be a kstat? */
	curpool = &io_pool_4g;
domore:
	/*
	 * Loop through taking pages from the end of the list
	 * (highest mfns) till amount to return reached.
	 */
	for (pp = *curpool; pp && retcnt > 0; ) {
		pp_first = pp_last = pp->p_prev;
		if (pp_first == *curpool)
			break;
		retcnt--;
		io_pool_cnt--;
		page_io_pool_sub(curpool, pp_first, pp_last);
		if ((mfn = pfn_to_mfn(pp->p_pagenum)) < start_mfn)
			start_mfn = mfn;
		page_free(pp_first, 1);
		pp = *curpool;
	}
	if (retcnt != 0 && !bothpools) {
		/*
		 * If not enough found in less constrained pool try the
		 * more constrained one.
		 */
		curpool = &io_pool_16m;
		bothpools = 1;
		goto domore;
	}
done:
	mutex_exit(&io_pool_lock);
}

#endif	/* __xpv */

uint_t
page_create_update_flags_x86(uint_t flags)
{
#if defined(__xpv)
	/*
	 * Check this is an urgent allocation and free pages are depleted.
	 */
	if (!(flags & PG_WAIT) && freemem < desfree)
		page_io_pool_shrink();
#else /* !__xpv */
	/*
	 * page_create_get_something may call this because 4g memory may be
	 * depleted. Set flags to allow for relocation of base page below
	 * 4g if necessary.
	 */
	if (physmax4g)
		flags |= (PGI_PGCPSZC0 | PGI_PGCPHIPRI);
#endif /* __xpv */
	return (flags);
}

/*ARGSUSED*/
int
bp_color(struct buf *bp)
{
	return (0);
}

#if defined(__xpv)

/*
 * Take pages out of an io_pool
 */
static void
page_io_pool_sub(page_t **poolp, page_t *pp_first, page_t *pp_last)
{
	if (*poolp == pp_first) {
		*poolp = pp_last->p_next;
		if (*poolp == pp_first)
			*poolp = NULL;
	}
	pp_first->p_prev->p_next = pp_last->p_next;
	pp_last->p_next->p_prev = pp_first->p_prev;
	pp_first->p_prev = pp_last;
	pp_last->p_next = pp_first;
}

/*
 * Put a page on the io_pool list. The list is ordered by increasing MFN.
 */
static void
page_io_pool_add(page_t **poolp, page_t *pp)
{
	page_t	*look;
	mfn_t	mfn = mfn_list[pp->p_pagenum];

	if (*poolp == NULL) {
		*poolp = pp;
		pp->p_next = pp;
		pp->p_prev = pp;
		return;
	}

	/*
	 * Since we try to take pages from the high end of the pool
	 * chances are good that the pages to be put on the list will
	 * go at or near the end of the list. so start at the end and
	 * work backwards.
	 */
	look = (*poolp)->p_prev;
	while (mfn < mfn_list[look->p_pagenum]) {
		look = look->p_prev;
		if (look == (*poolp)->p_prev)
			break; /* backed all the way to front of list */
	}

	/* insert after look */
	pp->p_prev = look;
	pp->p_next = look->p_next;
	pp->p_next->p_prev = pp;
	look->p_next = pp;
	if (mfn < mfn_list[(*poolp)->p_pagenum]) {
		/*
		 * we inserted a new first list element
		 * adjust pool pointer to newly inserted element
		 */
		*poolp = pp;
	}
}

/*
 * Add a page to the io_pool.  Setting the force flag will force the page
 * into the io_pool no matter what.
 */
static void
add_page_to_pool(page_t *pp, int force)
{
	page_t *highest;
	page_t *freep = NULL;

	mutex_enter(&io_pool_lock);
	/*
	 * Always keep the scarce low memory pages
	 */
	if (mfn_list[pp->p_pagenum] < PFN_16MEG) {
		++io_pool_cnt;
		page_io_pool_add(&io_pool_16m, pp);
		goto done;
	}
	if (io_pool_cnt < io_pool_cnt_max || force || io_pool_4g == NULL) {
		++io_pool_cnt;
		page_io_pool_add(&io_pool_4g, pp);
	} else {
		highest = io_pool_4g->p_prev;
		if (mfn_list[pp->p_pagenum] < mfn_list[highest->p_pagenum]) {
			page_io_pool_sub(&io_pool_4g, highest, highest);
			page_io_pool_add(&io_pool_4g, pp);
			freep = highest;
		} else {
			freep = pp;
		}
	}
done:
	mutex_exit(&io_pool_lock);
	if (freep)
		page_free(freep, 1);
}


int contig_pfn_cnt;	/* no of pfns in the contig pfn list */
int contig_pfn_max;	/* capacity of the contig pfn list */
int next_alloc_pfn;	/* next position in list to start a contig search */
int contig_pfnlist_updates;	/* pfn list update count */
int contig_pfnlist_builds;	/* how many times have we (re)built list */
int contig_pfnlist_buildfailed;	/* how many times has list build failed */
int create_contig_pending;	/* nonzero means taskq creating contig list */
pfn_t *contig_pfn_list = NULL;	/* list of contig pfns in ascending mfn order */

/*
 * Function to use in sorting a list of pfns by their underlying mfns.
 */
static int
mfn_compare(const void *pfnp1, const void *pfnp2)
{
	mfn_t mfn1 = mfn_list[*(pfn_t *)pfnp1];
	mfn_t mfn2 = mfn_list[*(pfn_t *)pfnp2];

	if (mfn1 > mfn2)
		return (1);
	if (mfn1 < mfn2)
		return (-1);
	return (0);
}

/*
 * Compact the contig_pfn_list by tossing all the non-contiguous
 * elements from the list.
 */
static void
compact_contig_pfn_list(void)
{
	pfn_t pfn, lapfn, prev_lapfn;
	mfn_t mfn;
	int i, newcnt = 0;

	prev_lapfn = 0;
	for (i = 0; i < contig_pfn_cnt - 1; i++) {
		pfn = contig_pfn_list[i];
		lapfn = contig_pfn_list[i + 1];
		mfn = mfn_list[pfn];
		/*
		 * See if next pfn is for a contig mfn
		 */
		if (mfn_list[lapfn] != mfn + 1)
			continue;
		/*
		 * pfn and lookahead are both put in list
		 * unless pfn is the previous lookahead.
		 */
		if (pfn != prev_lapfn)
			contig_pfn_list[newcnt++] = pfn;
		contig_pfn_list[newcnt++] = lapfn;
		prev_lapfn = lapfn;
	}
	for (i = newcnt; i < contig_pfn_cnt; i++)
		contig_pfn_list[i] = 0;
	contig_pfn_cnt = newcnt;
}

/*ARGSUSED*/
static void
call_create_contiglist(void *arg)
{
	(void) create_contig_pfnlist(PG_WAIT);
}

/*
 * Create list of freelist pfns that have underlying
 * contiguous mfns.  The list is kept in ascending mfn order.
 * returns 1 if list created else 0.
 */
static int
create_contig_pfnlist(uint_t flags)
{
	pfn_t pfn;
	page_t *pp;
	int ret = 1;

	mutex_enter(&contig_list_lock);
	if (contig_pfn_list != NULL)
		goto out;
	contig_pfn_max = freemem + (freemem / 10);
	contig_pfn_list = kmem_zalloc(contig_pfn_max * sizeof (pfn_t),
	    (flags & PG_WAIT) ? KM_SLEEP : KM_NOSLEEP);
	if (contig_pfn_list == NULL) {
		/*
		 * If we could not create the contig list (because
		 * we could not sleep for memory).  Dispatch a taskq that can
		 * sleep to get the memory.
		 */
		if (!create_contig_pending) {
			if (taskq_dispatch(system_taskq, call_create_contiglist,
			    NULL, TQ_NOSLEEP) != NULL)
				create_contig_pending = 1;
		}
		contig_pfnlist_buildfailed++;	/* count list build failures */
		ret = 0;
		goto out;
	}
	create_contig_pending = 0;
	ASSERT(contig_pfn_cnt == 0);
	for (pfn = 0; pfn < mfn_count; pfn++) {
		pp = page_numtopp_nolock(pfn);
		if (pp == NULL || !PP_ISFREE(pp))
			continue;
		contig_pfn_list[contig_pfn_cnt] = pfn;
		if (++contig_pfn_cnt == contig_pfn_max)
			break;
	}
	/*
	 * Sanity check the new list.
	 */
	if (contig_pfn_cnt < 2) { /* no contig pfns */
		contig_pfn_cnt = 0;
		contig_pfnlist_buildfailed++;
		kmem_free(contig_pfn_list, contig_pfn_max * sizeof (pfn_t));
		contig_pfn_list = NULL;
		contig_pfn_max = 0;
		ret = 0;
		goto out;
	}
	qsort(contig_pfn_list, contig_pfn_cnt, sizeof (pfn_t), mfn_compare);
	compact_contig_pfn_list();
	/*
	 * Make sure next search of the newly created contiguous pfn
	 * list starts at the beginning of the list.
	 */
	next_alloc_pfn = 0;
	contig_pfnlist_builds++;	/* count list builds */
out:
	mutex_exit(&contig_list_lock);
	return (ret);
}


/*
 * Toss the current contig pfnlist.  Someone is about to do a massive
 * update to pfn<->mfn mappings.  So we have them destroy the list and lock
 * it till they are done with their update.
 */
void
clear_and_lock_contig_pfnlist()
{
	pfn_t *listp = NULL;
	size_t listsize;

	mutex_enter(&contig_list_lock);
	if (contig_pfn_list != NULL) {
		listp = contig_pfn_list;
		listsize = contig_pfn_max * sizeof (pfn_t);
		contig_pfn_list = NULL;
		contig_pfn_max = contig_pfn_cnt = 0;
	}
	if (listp != NULL)
		kmem_free(listp, listsize);
}

/*
 * Unlock the contig_pfn_list.  The next attempted use of it will cause
 * it to be re-created.
 */
void
unlock_contig_pfnlist()
{
	mutex_exit(&contig_list_lock);
}

/*
 * Update the contiguous pfn list in response to a pfn <-> mfn reassignment
 */
void
update_contig_pfnlist(pfn_t pfn, mfn_t oldmfn, mfn_t newmfn)
{
	int probe_hi, probe_lo, probe_pos, insert_after, insert_point;
	pfn_t probe_pfn;
	mfn_t probe_mfn;
	int drop_lock = 0;

	if (mutex_owner(&contig_list_lock) != curthread) {
		drop_lock = 1;
		mutex_enter(&contig_list_lock);
	}
	if (contig_pfn_list == NULL)
		goto done;
	contig_pfnlist_updates++;
	/*
	 * Find the pfn in the current list.  Use a binary chop to locate it.
	 */
	probe_hi = contig_pfn_cnt - 1;
	probe_lo = 0;
	probe_pos = (probe_hi + probe_lo) / 2;
	while ((probe_pfn = contig_pfn_list[probe_pos]) != pfn) {
		if (probe_pos == probe_lo) { /* pfn not in list */
			probe_pos = -1;
			break;
		}
		if (pfn_to_mfn(probe_pfn) <= oldmfn)
			probe_lo = probe_pos;
		else
			probe_hi = probe_pos;
		probe_pos = (probe_hi + probe_lo) / 2;
	}
	if (probe_pos >= 0) {
		/*
		 * Remove pfn from list and ensure next alloc
		 * position stays in bounds.
		 */
		if (--contig_pfn_cnt <= next_alloc_pfn)
			next_alloc_pfn = 0;
		if (contig_pfn_cnt < 2) { /* no contig pfns */
			contig_pfn_cnt = 0;
			kmem_free(contig_pfn_list,
			    contig_pfn_max * sizeof (pfn_t));
			contig_pfn_list = NULL;
			contig_pfn_max = 0;
			goto done;
		}
		ovbcopy(&contig_pfn_list[probe_pos + 1],
		    &contig_pfn_list[probe_pos],
		    (contig_pfn_cnt - probe_pos) * sizeof (pfn_t));
	}
	if (newmfn == MFN_INVALID)
		goto done;
	/*
	 * Check if new mfn has adjacent mfns in the list
	 */
	probe_hi = contig_pfn_cnt - 1;
	probe_lo = 0;
	insert_after = -2;
	do {
		probe_pos = (probe_hi + probe_lo) / 2;
		probe_mfn = pfn_to_mfn(contig_pfn_list[probe_pos]);
		if (newmfn == probe_mfn + 1)
			insert_after = probe_pos;
		else if (newmfn == probe_mfn - 1)
			insert_after = probe_pos - 1;
		if (probe_pos == probe_lo)
			break;
		if (probe_mfn <= newmfn)
			probe_lo = probe_pos;
		else
			probe_hi = probe_pos;
	} while (insert_after == -2);
	/*
	 * If there is space in the list and there are adjacent mfns
	 * insert the pfn in to its proper place in the list.
	 */
	if (insert_after != -2 && contig_pfn_cnt + 1 <= contig_pfn_max) {
		insert_point = insert_after + 1;
		ovbcopy(&contig_pfn_list[insert_point],
		    &contig_pfn_list[insert_point + 1],
		    (contig_pfn_cnt - insert_point) * sizeof (pfn_t));
		contig_pfn_list[insert_point] = pfn;
		contig_pfn_cnt++;
	}
done:
	if (drop_lock)
		mutex_exit(&contig_list_lock);
}

/*
 * Called to (re-)populate the io_pool from the free page lists.
 */
long
populate_io_pool(void)
{
	pfn_t pfn;
	mfn_t mfn, max_mfn;
	page_t *pp;

	/*
	 * Figure out the bounds of the pool on first invocation.
	 * We use a percentage of memory for the io pool size.
	 * we allow that to shrink, but not to less than a fixed minimum
	 */
	if (io_pool_cnt_max == 0) {
		io_pool_cnt_max = physmem / (100 / io_pool_physmem_pct);
		io_pool_cnt_lowater = io_pool_cnt_max;
		/*
		 * This is the first time in populate_io_pool, grab a va to use
		 * when we need to allocate pages.
		 */
		io_pool_kva = vmem_alloc(heap_arena, PAGESIZE, VM_SLEEP);
	}
	/*
	 * If we are out of pages in the pool, then grow the size of the pool
	 */
	if (io_pool_cnt == 0) {
		/*
		 * Grow the max size of the io pool by 5%, but never more than
		 * 25% of physical memory.
		 */
		if (io_pool_cnt_max < physmem / 4)
			io_pool_cnt_max += io_pool_cnt_max / 20;
	}
	io_pool_grows++;	/* should be a kstat? */

	/*
	 * Get highest mfn on this platform, but limit to the 32 bit DMA max.
	 */
	(void) mfn_to_pfn(start_mfn);
	max_mfn = MIN(cached_max_mfn, PFN_4GIG);
	for (mfn = start_mfn; mfn < max_mfn; start_mfn = ++mfn) {
		pfn = mfn_to_pfn(mfn);
		if (pfn & PFN_IS_FOREIGN_MFN)
			continue;
		/*
		 * try to allocate it from free pages
		 */
		pp = page_numtopp_alloc(pfn);
		if (pp == NULL)
			continue;
		PP_CLRFREE(pp);
		add_page_to_pool(pp, 1);
		if (io_pool_cnt >= io_pool_cnt_max)
			break;
	}

	return (io_pool_cnt);
}

/*
 * Destroy a page that was being used for DMA I/O. It may or
 * may not actually go back to the io_pool.
 */
void
page_destroy_io(page_t *pp)
{
	mfn_t mfn = mfn_list[pp->p_pagenum];

	/*
	 * When the page was alloc'd a reservation was made, release it now
	 */
	page_unresv(1);
	/*
	 * Unload translations, if any, then hash out the
	 * page to erase its identity.
	 */
	(void) hat_pageunload(pp, HAT_FORCE_PGUNLOAD);
	page_hashout(pp, NULL);

	/*
	 * If the page came from the free lists, just put it back to them.
	 * DomU pages always go on the free lists as well.
	 */
	if (!DOMAIN_IS_INITDOMAIN(xen_info) || mfn >= PFN_4GIG) {
		page_free(pp, 1);
		return;
	}

	add_page_to_pool(pp, 0);
}


long contig_searches;		/* count of times contig pages requested */
long contig_search_restarts;	/* count of contig ranges tried */
long contig_search_failed;	/* count of contig alloc failures */

/*
 * Free partial page list
 */
static void
free_partial_list(page_t **pplist)
{
	page_t *pp;

	while (*pplist != NULL) {
		pp = *pplist;
		page_io_pool_sub(pplist, pp, pp);
		page_free(pp, 1);
	}
}

/*
 * Look thru the contiguous pfns that are not part of the io_pool for
 * contiguous free pages.  Return a list of the found pages or NULL.
 */
page_t *
find_contig_free(uint_t npages, uint_t flags, uint64_t pfnseg,
    pgcnt_t pfnalign)
{
	page_t *pp, *plist = NULL;
	mfn_t mfn, prev_mfn, start_mfn;
	pfn_t pfn;
	int pages_needed, pages_requested;
	int search_start;

	/*
	 * create the contig pfn list if not already done
	 */
retry:
	mutex_enter(&contig_list_lock);
	if (contig_pfn_list == NULL) {
		mutex_exit(&contig_list_lock);
		if (!create_contig_pfnlist(flags)) {
			return (NULL);
		}
		goto retry;
	}
	contig_searches++;
	/*
	 * Search contiguous pfn list for physically contiguous pages not in
	 * the io_pool.  Start the search where the last search left off.
	 */
	pages_requested = pages_needed = npages;
	search_start = next_alloc_pfn;
	start_mfn = prev_mfn = 0;
	while (pages_needed) {
		pfn = contig_pfn_list[next_alloc_pfn];
		mfn = pfn_to_mfn(pfn);
		/*
		 * Check if mfn is first one or contig to previous one and
		 * if page corresponding to mfn is free and that mfn
		 * range is not crossing a segment boundary.
		 */
		if ((prev_mfn == 0 || mfn == prev_mfn + 1) &&
		    (pp = page_numtopp_alloc(pfn)) != NULL &&
		    !((mfn & pfnseg) < (start_mfn & pfnseg))) {
			PP_CLRFREE(pp);
			page_io_pool_add(&plist, pp);
			pages_needed--;
			if (prev_mfn == 0) {
				if (pfnalign &&
				    mfn != P2ROUNDUP(mfn, pfnalign)) {
					/*
					 * not properly aligned
					 */
					contig_search_restarts++;
					free_partial_list(&plist);
					pages_needed = pages_requested;
					start_mfn = prev_mfn = 0;
					goto skip;
				}
				start_mfn = mfn;
			}
			prev_mfn = mfn;
		} else {
			contig_search_restarts++;
			free_partial_list(&plist);
			pages_needed = pages_requested;
			start_mfn = prev_mfn = 0;
		}
skip:
		if (++next_alloc_pfn == contig_pfn_cnt)
			next_alloc_pfn = 0;
		if (next_alloc_pfn == search_start)
			break; /* all pfns searched */
	}
	mutex_exit(&contig_list_lock);
	if (pages_needed) {
		contig_search_failed++;
		/*
		 * Failed to find enough contig pages.
		 * free partial page list
		 */
		free_partial_list(&plist);
	}
	return (plist);
}

/*
 * Search the reserved io pool pages for a page range with the
 * desired characteristics.
 */
page_t *
page_io_pool_alloc(ddi_dma_attr_t *mattr, int contig, pgcnt_t minctg)
{
	page_t *pp_first, *pp_last;
	page_t *pp, **poolp;
	pgcnt_t nwanted, pfnalign;
	uint64_t pfnseg;
	mfn_t mfn, tmfn, hi_mfn, lo_mfn;
	int align, attempt = 0;

	if (minctg == 1)
		contig = 0;
	lo_mfn = mmu_btop(mattr->dma_attr_addr_lo);
	hi_mfn = mmu_btop(mattr->dma_attr_addr_hi);
	pfnseg = mmu_btop(mattr->dma_attr_seg);
	align = maxbit(mattr->dma_attr_align, mattr->dma_attr_minxfer);
	if (align > MMU_PAGESIZE)
		pfnalign = mmu_btop(align);
	else
		pfnalign = 0;

try_again:
	/*
	 * See if we want pages for a legacy device
	 */
	if (hi_mfn < PFN_16MEG)
		poolp = &io_pool_16m;
	else
		poolp = &io_pool_4g;
try_smaller:
	/*
	 * Take pages from I/O pool. We'll use pages from the highest
	 * MFN range possible.
	 */
	pp_first = pp_last = NULL;
	mutex_enter(&io_pool_lock);
	nwanted = minctg;
	for (pp = *poolp; pp && nwanted > 0; ) {
		pp = pp->p_prev;

		/*
		 * skip pages above allowable range
		 */
		mfn = mfn_list[pp->p_pagenum];
		if (hi_mfn < mfn)
			goto skip;

		/*
		 * stop at pages below allowable range
		 */
		if (lo_mfn > mfn)
			break;
restart:
		if (pp_last == NULL) {
			/*
			 * Check alignment
			 */
			tmfn = mfn - (minctg - 1);
			if (pfnalign && tmfn != P2ROUNDUP(tmfn, pfnalign))
				goto skip; /* not properly aligned */
			/*
			 * Check segment
			 */
			if ((mfn & pfnseg) < (tmfn & pfnseg))
				goto skip; /* crosses seg boundary */
			/*
			 * Start building page list
			 */
			pp_first = pp_last = pp;
			nwanted--;
		} else {
			/*
			 * check physical contiguity if required
			 */
			if (contig &&
			    mfn_list[pp_first->p_pagenum] != mfn + 1) {
				/*
				 * not a contiguous page, restart list.
				 */
				pp_last = NULL;
				nwanted = minctg;
				goto restart;
			} else { /* add page to list */
				pp_first = pp;
				nwanted--;
			}
		}
skip:
		if (pp == *poolp)
			break;
	}

	/*
	 * If we didn't find memory. Try the more constrained pool, then
	 * sweep free pages into the DMA pool and try again.
	 */
	if (nwanted != 0) {
		mutex_exit(&io_pool_lock);
		/*
		 * If we were looking in the less constrained pool and
		 * didn't find pages, try the more constrained pool.
		 */
		if (poolp == &io_pool_4g) {
			poolp = &io_pool_16m;
			goto try_smaller;
		}
		kmem_reap();
		if (++attempt < 4) {
			/*
			 * Grab some more io_pool pages
			 */
			(void) populate_io_pool();
			goto try_again; /* go around and retry */
		}
		return (NULL);
	}
	/*
	 * Found the pages, now snip them from the list
	 */
	page_io_pool_sub(poolp, pp_first, pp_last);
	io_pool_cnt -= minctg;
	/*
	 * reset low water mark
	 */
	if (io_pool_cnt < io_pool_cnt_lowater)
		io_pool_cnt_lowater = io_pool_cnt;
	mutex_exit(&io_pool_lock);
	return (pp_first);
}

page_t *
page_swap_with_hypervisor(struct vnode *vp, u_offset_t off, caddr_t vaddr,
    ddi_dma_attr_t *mattr, uint_t flags, pgcnt_t minctg)
{
	uint_t kflags;
	int order, extra, extpages, i, contig, nbits, extents;
	page_t *pp, *expp, *pp_first, **pplist = NULL;
	mfn_t *mfnlist = NULL;

	contig = flags & PG_PHYSCONTIG;
	if (minctg == 1)
		contig = 0;
	flags &= ~PG_PHYSCONTIG;
	kflags = flags & PG_WAIT ? KM_SLEEP : KM_NOSLEEP;
	/*
	 * Hypervisor will allocate extents, if we want contig
	 * pages extent must be >= minctg
	 */
	if (contig) {
		order = highbit(minctg) - 1;
		if (minctg & ((1 << order) - 1))
			order++;
		extpages = 1 << order;
	} else {
		order = 0;
		extpages = minctg;
	}
	if (extpages > minctg) {
		extra = extpages - minctg;
		if (!page_resv(extra, kflags))
			return (NULL);
	}
	pp_first = NULL;
	pplist = kmem_alloc(extpages * sizeof (page_t *), kflags);
	if (pplist == NULL)
		goto balloon_fail;
	mfnlist = kmem_alloc(extpages * sizeof (mfn_t), kflags);
	if (mfnlist == NULL)
		goto balloon_fail;
	pp = page_create_va(vp, off, minctg * PAGESIZE, flags, &kvseg, vaddr);
	if (pp == NULL)
		goto balloon_fail;
	pp_first = pp;
	if (extpages > minctg) {
		/*
		 * fill out the rest of extent pages to swap
		 * with the hypervisor
		 */
		for (i = 0; i < extra; i++) {
			expp = page_create_va(vp,
			    (u_offset_t)(uintptr_t)io_pool_kva,
			    PAGESIZE, flags, &kvseg, io_pool_kva);
			if (expp == NULL)
				goto balloon_fail;
			(void) hat_pageunload(expp, HAT_FORCE_PGUNLOAD);
			page_io_unlock(expp);
			page_hashout(expp, NULL);
			page_io_lock(expp);
			/*
			 * add page to end of list
			 */
			expp->p_prev = pp_first->p_prev;
			expp->p_next = pp_first;
			expp->p_prev->p_next = expp;
			pp_first->p_prev = expp;
		}

	}
	for (i = 0; i < extpages; i++) {
		pplist[i] = pp;
		pp = pp->p_next;
	}
	nbits = highbit(mattr->dma_attr_addr_hi);
	extents = contig ? 1 : minctg;
	if (balloon_replace_pages(extents, pplist, nbits, order,
	    mfnlist) != extents) {
		if (ioalloc_dbg)
			cmn_err(CE_NOTE, "request to hypervisor"
			    " for %d pages, maxaddr %" PRIx64 " failed",
			    extpages, mattr->dma_attr_addr_hi);
		goto balloon_fail;
	}

	kmem_free(pplist, extpages * sizeof (page_t *));
	kmem_free(mfnlist, extpages * sizeof (mfn_t));
	/*
	 * Return any excess pages to free list
	 */
	if (extpages > minctg) {
		for (i = 0; i < extra; i++) {
			pp = pp_first->p_prev;
			page_sub(&pp_first, pp);
			page_io_unlock(pp);
			page_unresv(1);
			page_free(pp, 1);
		}
	}
	return (pp_first);
balloon_fail:
	/*
	 * Return pages to free list and return failure
	 */
	while (pp_first != NULL) {
		pp = pp_first;
		page_sub(&pp_first, pp);
		page_io_unlock(pp);
		if (pp->p_vnode != NULL)
			page_hashout(pp, NULL);
		page_free(pp, 1);
	}
	if (pplist)
		kmem_free(pplist, extpages * sizeof (page_t *));
	if (mfnlist)
		kmem_free(mfnlist, extpages * sizeof (mfn_t));
	page_unresv(extpages - minctg);
	return (NULL);
}

static void
return_partial_alloc(page_t *plist)
{
	page_t *pp;

	while (plist != NULL) {
		pp = plist;
		page_sub(&plist, pp);
		page_io_unlock(pp);
		page_destroy_io(pp);
	}
}

static page_t *
page_get_contigpages(
	struct vnode	*vp,
	u_offset_t	off,
	int		*npagesp,
	uint_t		flags,
	caddr_t		vaddr,
	ddi_dma_attr_t	*mattr)
{
	mfn_t	max_mfn = HYPERVISOR_memory_op(XENMEM_maximum_ram_page, NULL);
	page_t	*plist;	/* list to return */
	page_t	*pp, *mcpl;
	int	contig, anyaddr, npages, getone = 0;
	mfn_t	lo_mfn;
	mfn_t	hi_mfn;
	pgcnt_t	pfnalign = 0;
	int	align, sgllen;
	uint64_t pfnseg;
	pgcnt_t	minctg;

	npages = *npagesp;
	ASSERT(mattr != NULL);
	lo_mfn = mmu_btop(mattr->dma_attr_addr_lo);
	hi_mfn = mmu_btop(mattr->dma_attr_addr_hi);
	sgllen = mattr->dma_attr_sgllen;
	pfnseg = mmu_btop(mattr->dma_attr_seg);
	align = maxbit(mattr->dma_attr_align, mattr->dma_attr_minxfer);
	if (align > MMU_PAGESIZE)
		pfnalign = mmu_btop(align);

	contig = flags & PG_PHYSCONTIG;
	if (npages == -1) {
		npages = 1;
		pfnalign = 0;
	}
	/*
	 * Clear the contig flag if only one page is needed.
	 */
	if (npages == 1) {
		getone = 1;
		contig = 0;
	}

	/*
	 * Check if any page in the system is fine.
	 */
	anyaddr = lo_mfn == 0 && hi_mfn >= max_mfn;
	if (!contig && anyaddr && !pfnalign) {
		flags &= ~PG_PHYSCONTIG;
		plist = page_create_va(vp, off, npages * MMU_PAGESIZE,
		    flags, &kvseg, vaddr);
		if (plist != NULL) {
			*npagesp = 0;
			return (plist);
		}
	}
	plist = NULL;
	minctg = howmany(npages, sgllen);
	while (npages > sgllen || getone) {
		if (minctg > npages)
			minctg = npages;
		mcpl = NULL;
		/*
		 * We could want contig pages with no address range limits.
		 */
		if (anyaddr && contig) {
			/*
			 * Look for free contig pages to satisfy the request.
			 */
			mcpl = find_contig_free(minctg, flags, pfnseg,
			    pfnalign);
		}
		/*
		 * Try the reserved io pools next
		 */
		if (mcpl == NULL)
			mcpl = page_io_pool_alloc(mattr, contig, minctg);
		if (mcpl != NULL) {
			pp = mcpl;
			do {
				if (!page_hashin(pp, vp, off, NULL)) {
					panic("page_get_contigpages:"
					    " hashin failed"
					    " pp %p, vp %p, off %llx",
					    (void *)pp, (void *)vp, off);
				}
				off += MMU_PAGESIZE;
				PP_CLRFREE(pp);
				PP_CLRAGED(pp);
				page_set_props(pp, P_REF);
				page_io_lock(pp);
				pp = pp->p_next;
			} while (pp != mcpl);
		} else {
			/*
			 * Hypervisor exchange doesn't handle segment or
			 * alignment constraints
			 */
			if (mattr->dma_attr_seg < mattr->dma_attr_addr_hi ||
			    pfnalign)
				goto fail;
			/*
			 * Try exchanging pages with the hypervisor
			 */
			mcpl = page_swap_with_hypervisor(vp, off, vaddr, mattr,
			    flags, minctg);
			if (mcpl == NULL)
				goto fail;
			off += minctg * MMU_PAGESIZE;
		}
		check_dma(mattr, mcpl, minctg);
		/*
		 * Here with a minctg run of contiguous pages, add them to the
		 * list we will return for this request.
		 */
		page_list_concat(&plist, &mcpl);
		npages -= minctg;
		*npagesp = npages;
		sgllen--;
		if (getone)
			break;
	}
	return (plist);
fail:
	return_partial_alloc(plist);
	return (NULL);
}

/*
 * Allocator for domain 0 I/O pages. We match the required
 * DMA attributes and contiguity constraints.
 */
/*ARGSUSED*/
page_t *
page_create_io(
	struct vnode	*vp,
	u_offset_t	off,
	uint_t		bytes,
	uint_t		flags,
	struct as	*as,
	caddr_t		vaddr,
	ddi_dma_attr_t	*mattr)
{
	page_t	*plist = NULL, *pp;
	int	npages = 0, contig, anyaddr, pages_req;
	mfn_t	lo_mfn;
	mfn_t	hi_mfn;
	pgcnt_t	pfnalign = 0;
	int	align;
	int	is_domu = 0;
	int	dummy, bytes_got;
	mfn_t	max_mfn = HYPERVISOR_memory_op(XENMEM_maximum_ram_page, NULL);

	ASSERT(mattr != NULL);
	lo_mfn = mmu_btop(mattr->dma_attr_addr_lo);
	hi_mfn = mmu_btop(mattr->dma_attr_addr_hi);
	align = maxbit(mattr->dma_attr_align, mattr->dma_attr_minxfer);
	if (align > MMU_PAGESIZE)
		pfnalign = mmu_btop(align);

	/*
	 * Clear the contig flag if only one page is needed or the scatter
	 * gather list length is >= npages.
	 */
	pages_req = npages = mmu_btopr(bytes);
	contig = (flags & PG_PHYSCONTIG);
	bytes = P2ROUNDUP(bytes, MMU_PAGESIZE);
	if (bytes == MMU_PAGESIZE || mattr->dma_attr_sgllen >= npages)
		contig = 0;

	/*
	 * Check if any old page in the system is fine.
	 * DomU should always go down this path.
	 */
	is_domu = !DOMAIN_IS_INITDOMAIN(xen_info);
	anyaddr = lo_mfn == 0 && hi_mfn >= max_mfn && !pfnalign;
	if ((!contig && anyaddr) || is_domu) {
		flags &= ~PG_PHYSCONTIG;
		plist = page_create_va(vp, off, bytes, flags, &kvseg, vaddr);
		if (plist != NULL)
			return (plist);
		else if (is_domu)
			return (NULL); /* no memory available */
	}
	/*
	 * DomU should never reach here
	 */
	if (contig) {
		plist = page_get_contigpages(vp, off, &npages, flags, vaddr,
		    mattr);
		if (plist == NULL)
			goto fail;
		bytes_got = (pages_req - npages) << MMU_PAGESHIFT;
		vaddr += bytes_got;
		off += bytes_got;
		/*
		 * We now have all the contiguous pages we need, but
		 * we may still need additional non-contiguous pages.
		 */
	}
	/*
	 * now loop collecting the requested number of pages, these do
	 * not have to be contiguous pages but we will use the contig
	 * page alloc code to get the pages since it will honor any
	 * other constraints the pages may have.
	 */
	while (npages--) {
		dummy = -1;
		pp = page_get_contigpages(vp, off, &dummy, flags, vaddr, mattr);
		if (pp == NULL)
			goto fail;
		page_add(&plist, pp);
		vaddr += MMU_PAGESIZE;
		off += MMU_PAGESIZE;
	}
	return (plist);
fail:
	/*
	 * Failed to get enough pages, return ones we did get
	 */
	return_partial_alloc(plist);
	return (NULL);
}

/*
 * Lock and return the page with the highest mfn that we can find.  last_mfn
 * holds the last one found, so the next search can start from there.  We
 * also keep a counter so that we don't loop forever if the machine has no
 * free pages.
 *
 * This is called from the balloon thread to find pages to give away.  new_high
 * is used when new mfn's have been added to the system - we will reset our
 * search if the new mfn's are higher than our current search position.
 */
page_t *
page_get_high_mfn(mfn_t new_high)
{
	static mfn_t last_mfn = 0;
	pfn_t pfn;
	page_t *pp;
	ulong_t loop_count = 0;

	if (new_high > last_mfn)
		last_mfn = new_high;

	for (; loop_count < mfn_count; loop_count++, last_mfn--) {
		if (last_mfn == 0) {
			last_mfn = cached_max_mfn;
		}

		pfn = mfn_to_pfn(last_mfn);
		if (pfn & PFN_IS_FOREIGN_MFN)
			continue;

		/* See if the page is free.  If so, lock it. */
		pp = page_numtopp_alloc(pfn);
		if (pp == NULL)
			continue;
		PP_CLRFREE(pp);

		ASSERT(PAGE_EXCL(pp));
		ASSERT(pp->p_vnode == NULL);
		ASSERT(!hat_page_is_mapped(pp));
		last_mfn--;
		return (pp);
	}
	return (NULL);
}

#else /* !__xpv */

/*
 * get a page from any list with the given mnode
 */
static page_t *
page_get_mnode_anylist(ulong_t origbin, uchar_t szc, uint_t flags,
    int mnode, int mtype, ddi_dma_attr_t *dma_attr)
{
	kmutex_t		*pcm;
	int			i;
	page_t			*pp;
	page_t			*first_pp;
	uint64_t		pgaddr;
	ulong_t			bin;
	int			mtypestart;
	int			plw_initialized;
	page_list_walker_t	plw;

	VM_STAT_ADD(pga_vmstats.pgma_alloc);

	ASSERT((flags & PG_MATCH_COLOR) == 0);
	ASSERT(szc == 0);
	ASSERT(dma_attr != NULL);

	MTYPE_START(mnode, mtype, flags);
	if (mtype < 0) {
		VM_STAT_ADD(pga_vmstats.pgma_allocempty);
		return (NULL);
	}

	mtypestart = mtype;

	bin = origbin;

	/*
	 * check up to page_colors + 1 bins - origbin may be checked twice
	 * because of BIN_STEP skip
	 */
	do {
		plw_initialized = 0;

		for (plw.plw_count = 0;
		    plw.plw_count < page_colors; plw.plw_count++) {

			if (PAGE_FREELISTS(mnode, szc, bin, mtype) == NULL)
				goto nextfreebin;

			pcm = PC_BIN_MUTEX(mnode, bin, PG_FREE_LIST);
			mutex_enter(pcm);
			pp = PAGE_FREELISTS(mnode, szc, bin, mtype);
			first_pp = pp;
			while (pp != NULL) {
				if (page_trylock(pp, SE_EXCL) == 0) {
					pp = pp->p_next;
					if (pp == first_pp) {
						pp = NULL;
					}
					continue;
				}

				ASSERT(PP_ISFREE(pp));
				ASSERT(PP_ISAGED(pp));
				ASSERT(pp->p_vnode == NULL);
				ASSERT(pp->p_hash == NULL);
				ASSERT(pp->p_offset == (u_offset_t)-1);
				ASSERT(pp->p_szc == szc);
				ASSERT(PFN_2_MEM_NODE(pp->p_pagenum) == mnode);
				/* check if page within DMA attributes */
				pgaddr = pa_to_ma(pfn_to_pa(pp->p_pagenum));
				if ((pgaddr >= dma_attr->dma_attr_addr_lo) &&
				    (pgaddr + MMU_PAGESIZE - 1 <=
				    dma_attr->dma_attr_addr_hi)) {
					break;
				}

				/* continue looking */
				page_unlock(pp);
				pp = pp->p_next;
				if (pp == first_pp)
					pp = NULL;

			}
			if (pp != NULL) {
				ASSERT(mtype == PP_2_MTYPE(pp));
				ASSERT(pp->p_szc == 0);

				/* found a page with specified DMA attributes */
				page_sub(&PAGE_FREELISTS(mnode, szc, bin,
				    mtype), pp);
				page_ctr_sub(mnode, mtype, pp, PG_FREE_LIST);

				if ((PP_ISFREE(pp) == 0) ||
				    (PP_ISAGED(pp) == 0)) {
					cmn_err(CE_PANIC, "page %p is not free",
					    (void *)pp);
				}

				mutex_exit(pcm);
				check_dma(dma_attr, pp, 1);
				VM_STAT_ADD(pga_vmstats.pgma_allocok);
				return (pp);
			}
			mutex_exit(pcm);
nextfreebin:
			if (plw_initialized == 0) {
				page_list_walk_init(szc, 0, bin, 1, 0, &plw);
				ASSERT(plw.plw_ceq_dif == page_colors);
				plw_initialized = 1;
			}

			if (plw.plw_do_split) {
				pp = page_freelist_split(szc, bin, mnode,
				    mtype,
				    mmu_btop(dma_attr->dma_attr_addr_lo),
				    mmu_btop(dma_attr->dma_attr_addr_hi + 1),
				    &plw);
				if (pp != NULL) {
					check_dma(dma_attr, pp, 1);
					return (pp);
				}
			}

			bin = page_list_walk_next_bin(szc, bin, &plw);
		}

		MTYPE_NEXT(mnode, mtype, flags);
	} while (mtype >= 0);

	/* failed to find a page in the freelist; try it in the cachelist */

	/* reset mtype start for cachelist search */
	mtype = mtypestart;
	ASSERT(mtype >= 0);

	/* start with the bin of matching color */
	bin = origbin;

	do {
		for (i = 0; i <= page_colors; i++) {
			if (PAGE_CACHELISTS(mnode, bin, mtype) == NULL)
				goto nextcachebin;
			pcm = PC_BIN_MUTEX(mnode, bin, PG_CACHE_LIST);
			mutex_enter(pcm);
			pp = PAGE_CACHELISTS(mnode, bin, mtype);
			first_pp = pp;
			while (pp != NULL) {
				if (page_trylock(pp, SE_EXCL) == 0) {
					pp = pp->p_next;
					if (pp == first_pp)
						pp = NULL;
					continue;
				}
				ASSERT(pp->p_vnode);
				ASSERT(PP_ISAGED(pp) == 0);
				ASSERT(pp->p_szc == 0);
				ASSERT(PFN_2_MEM_NODE(pp->p_pagenum) == mnode);

				/* check if page within DMA attributes */

				pgaddr = pa_to_ma(pfn_to_pa(pp->p_pagenum));
				if ((pgaddr >= dma_attr->dma_attr_addr_lo) &&
				    (pgaddr + MMU_PAGESIZE - 1 <=
				    dma_attr->dma_attr_addr_hi)) {
					break;
				}

				/* continue looking */
				page_unlock(pp);
				pp = pp->p_next;
				if (pp == first_pp)
					pp = NULL;
			}

			if (pp != NULL) {
				ASSERT(mtype == PP_2_MTYPE(pp));
				ASSERT(pp->p_szc == 0);

				/* found a page with specified DMA attributes */
				page_sub(&PAGE_CACHELISTS(mnode, bin,
				    mtype), pp);
				page_ctr_sub(mnode, mtype, pp, PG_CACHE_LIST);

				mutex_exit(pcm);
				ASSERT(pp->p_vnode);
				ASSERT(PP_ISAGED(pp) == 0);
				check_dma(dma_attr, pp, 1);
				VM_STAT_ADD(pga_vmstats.pgma_allocok);
				return (pp);
			}
			mutex_exit(pcm);
nextcachebin:
			bin += (i == 0) ? BIN_STEP : 1;
			bin &= page_colors_mask;
		}
		MTYPE_NEXT(mnode, mtype, flags);
	} while (mtype >= 0);

	VM_STAT_ADD(pga_vmstats.pgma_allocfailed);
	return (NULL);
}

/*
 * This function is similar to page_get_freelist()/page_get_cachelist()
 * but it searches both the lists to find a page with the specified
 * color (or no color) and DMA attributes. The search is done in the
 * freelist first and then in the cache list within the highest memory
 * range (based on DMA attributes) before searching in the lower
 * memory ranges.
 *
 * Note: This function is called only by page_create_io().
 */
/*ARGSUSED*/
static page_t *
page_get_anylist(struct vnode *vp, u_offset_t off, struct as *as, caddr_t vaddr,
    size_t size, uint_t flags, ddi_dma_attr_t *dma_attr, lgrp_t	*lgrp)
{
	uint_t		bin;
	int		mtype;
	page_t		*pp;
	int		n;
	int		m;
	int		szc;
	int		fullrange;
	int		mnode;
	int		local_failed_stat = 0;
	lgrp_mnode_cookie_t	lgrp_cookie;

	VM_STAT_ADD(pga_vmstats.pga_alloc);

	/* only base pagesize currently supported */
	if (size != MMU_PAGESIZE)
		return (NULL);

	/*
	 * If we're passed a specific lgroup, we use it.  Otherwise,
	 * assume first-touch placement is desired.
	 */
	if (!LGRP_EXISTS(lgrp))
		lgrp = lgrp_home_lgrp();

	/* LINTED */
	AS_2_BIN(as, seg, vp, vaddr, bin, 0);

	/*
	 * Only hold one freelist or cachelist lock at a time, that way we
	 * can start anywhere and not have to worry about lock
	 * ordering.
	 */
	if (dma_attr == NULL) {
		n = mtype16m;
		m = mtypetop;
		fullrange = 1;
		VM_STAT_ADD(pga_vmstats.pga_nulldmaattr);
	} else {
		pfn_t pfnlo = mmu_btop(dma_attr->dma_attr_addr_lo);
		pfn_t pfnhi = mmu_btop(dma_attr->dma_attr_addr_hi);

		/*
		 * We can guarantee alignment only for page boundary.
		 */
		if (dma_attr->dma_attr_align > MMU_PAGESIZE)
			return (NULL);

		/* Sanity check the dma_attr */
		if (pfnlo > pfnhi)
			return (NULL);

		n = pfn_2_mtype(pfnlo);
		m = pfn_2_mtype(pfnhi);

		fullrange = ((pfnlo == mnoderanges[n].mnr_pfnlo) &&
		    (pfnhi >= mnoderanges[m].mnr_pfnhi));
	}
	VM_STAT_COND_ADD(fullrange == 0, pga_vmstats.pga_notfullrange);

	szc = 0;

	/* cylcing thru mtype handled by RANGE0 if n == mtype16m */
	if (n == mtype16m) {
		flags |= PGI_MT_RANGE0;
		n = m;
	}

	/*
	 * Try local memory node first, but try remote if we can't
	 * get a page of the right color.
	 */
	LGRP_MNODE_COOKIE_INIT(lgrp_cookie, lgrp, LGRP_SRCH_HIER);
	while ((mnode = lgrp_memnode_choose(&lgrp_cookie)) >= 0) {
		/*
		 * allocate pages from high pfn to low.
		 */
		mtype = m;
		do {
			if (fullrange != 0) {
				pp = page_get_mnode_freelist(mnode,
				    bin, mtype, szc, flags);
				if (pp == NULL) {
					pp = page_get_mnode_cachelist(
					    bin, flags, mnode, mtype);
				}
			} else {
				pp = page_get_mnode_anylist(bin, szc,
				    flags, mnode, mtype, dma_attr);
			}
			if (pp != NULL) {
				VM_STAT_ADD(pga_vmstats.pga_allocok);
				check_dma(dma_attr, pp, 1);
				return (pp);
			}
		} while (mtype != n &&
		    (mtype = mnoderanges[mtype].mnr_next) != -1);
		if (!local_failed_stat) {
			lgrp_stat_add(lgrp->lgrp_id, LGRP_NUM_ALLOC_FAIL, 1);
			local_failed_stat = 1;
		}
	}
	VM_STAT_ADD(pga_vmstats.pga_allocfailed);

	return (NULL);
}

/*
 * page_create_io()
 *
 * This function is a copy of page_create_va() with an additional
 * argument 'mattr' that specifies DMA memory requirements to
 * the page list functions. This function is used by the segkmem
 * allocator so it is only to create new pages (i.e PG_EXCL is
 * set).
 *
 * Note: This interface is currently used by x86 PSM only and is
 *	 not fully specified so the commitment level is only for
 *	 private interface specific to x86. This interface uses PSM
 *	 specific page_get_anylist() interface.
 */

#define	PAGE_HASH_SEARCH(index, pp, vp, off) { \
	for ((pp) = page_hash[(index)]; (pp); (pp) = (pp)->p_hash) { \
		if ((pp)->p_vnode == (vp) && (pp)->p_offset == (off)) \
			break; \
	} \
}


page_t *
page_create_io(
	struct vnode	*vp,
	u_offset_t	off,
	uint_t		bytes,
	uint_t		flags,
	struct as	*as,
	caddr_t		vaddr,
	ddi_dma_attr_t	*mattr)	/* DMA memory attributes if any */
{
	page_t		*plist = NULL;
	uint_t		plist_len = 0;
	pgcnt_t		npages;
	page_t		*npp = NULL;
	uint_t		pages_req;
	page_t		*pp;
	kmutex_t	*phm = NULL;
	uint_t		index;

	TRACE_4(TR_FAC_VM, TR_PAGE_CREATE_START,
	    "page_create_start:vp %p off %llx bytes %u flags %x",
	    vp, off, bytes, flags);

	ASSERT((flags & ~(PG_EXCL | PG_WAIT | PG_PHYSCONTIG)) == 0);

	pages_req = npages = mmu_btopr(bytes);

	/*
	 * Do the freemem and pcf accounting.
	 */
	if (!page_create_wait(npages, flags)) {
		return (NULL);
	}

	TRACE_2(TR_FAC_VM, TR_PAGE_CREATE_SUCCESS,
	    "page_create_success:vp %p off %llx", vp, off);

	/*
	 * If satisfying this request has left us with too little
	 * memory, start the wheels turning to get some back.  The
	 * first clause of the test prevents waking up the pageout
	 * daemon in situations where it would decide that there's
	 * nothing to do.
	 */
	if (nscan < desscan && freemem < minfree) {
		TRACE_1(TR_FAC_VM, TR_PAGEOUT_CV_SIGNAL,
		    "pageout_cv_signal:freemem %ld", freemem);
		cv_signal(&proc_pageout->p_cv);
	}

	if (flags & PG_PHYSCONTIG) {

		plist = page_get_contigpage(&npages, mattr, 1);
		if (plist == NULL) {
			page_create_putback(npages);
			return (NULL);
		}

		pp = plist;

		do {
			if (!page_hashin(pp, vp, off, NULL)) {
				panic("pg_creat_io: hashin failed %p %p %llx",
				    (void *)pp, (void *)vp, off);
			}
			VM_STAT_ADD(page_create_new);
			off += MMU_PAGESIZE;
			PP_CLRFREE(pp);
			PP_CLRAGED(pp);
			page_set_props(pp, P_REF);
			pp = pp->p_next;
		} while (pp != plist);

		if (!npages) {
			check_dma(mattr, plist, pages_req);
			return (plist);
		} else {
			vaddr += (pages_req - npages) << MMU_PAGESHIFT;
		}

		/*
		 * fall-thru:
		 *
		 * page_get_contigpage returns when npages <= sgllen.
		 * Grab the rest of the non-contig pages below from anylist.
		 */
	}

	/*
	 * Loop around collecting the requested number of pages.
	 * Most of the time, we have to `create' a new page. With
	 * this in mind, pull the page off the free list before
	 * getting the hash lock.  This will minimize the hash
	 * lock hold time, nesting, and the like.  If it turns
	 * out we don't need the page, we put it back at the end.
	 */
	while (npages--) {
		phm = NULL;

		index = PAGE_HASH_FUNC(vp, off);
top:
		ASSERT(phm == NULL);
		ASSERT(index == PAGE_HASH_FUNC(vp, off));
		ASSERT(MUTEX_NOT_HELD(page_vnode_mutex(vp)));

		if (npp == NULL) {
			/*
			 * Try to get the page of any color either from
			 * the freelist or from the cache list.
			 */
			npp = page_get_anylist(vp, off, as, vaddr, MMU_PAGESIZE,
			    flags & ~PG_MATCH_COLOR, mattr, NULL);
			if (npp == NULL) {
				if (mattr == NULL) {
					/*
					 * Not looking for a special page;
					 * panic!
					 */
					panic("no page found %d", (int)npages);
				}
				/*
				 * No page found! This can happen
				 * if we are looking for a page
				 * within a specific memory range
				 * for DMA purposes. If PG_WAIT is
				 * specified then we wait for a
				 * while and then try again. The
				 * wait could be forever if we
				 * don't get the page(s) we need.
				 *
				 * Note: XXX We really need a mechanism
				 * to wait for pages in the desired
				 * range. For now, we wait for any
				 * pages and see if we can use it.
				 */

				if ((mattr != NULL) && (flags & PG_WAIT)) {
					delay(10);
					goto top;
				}
				goto fail; /* undo accounting stuff */
			}

			if (PP_ISAGED(npp) == 0) {
				/*
				 * Since this page came from the
				 * cachelist, we must destroy the
				 * old vnode association.
				 */
				page_hashout(npp, (kmutex_t *)NULL);
			}
		}

		/*
		 * We own this page!
		 */
		ASSERT(PAGE_EXCL(npp));
		ASSERT(npp->p_vnode == NULL);
		ASSERT(!hat_page_is_mapped(npp));
		PP_CLRFREE(npp);
		PP_CLRAGED(npp);

		/*
		 * Here we have a page in our hot little mits and are
		 * just waiting to stuff it on the appropriate lists.
		 * Get the mutex and check to see if it really does
		 * not exist.
		 */
		phm = PAGE_HASH_MUTEX(index);
		mutex_enter(phm);
		PAGE_HASH_SEARCH(index, pp, vp, off);
		if (pp == NULL) {
			VM_STAT_ADD(page_create_new);
			pp = npp;
			npp = NULL;
			if (!page_hashin(pp, vp, off, phm)) {
				/*
				 * Since we hold the page hash mutex and
				 * just searched for this page, page_hashin
				 * had better not fail.  If it does, that
				 * means somethread did not follow the
				 * page hash mutex rules.  Panic now and
				 * get it over with.  As usual, go down
				 * holding all the locks.
				 */
				ASSERT(MUTEX_HELD(phm));
				panic("page_create: hashin fail %p %p %llx %p",
				    (void *)pp, (void *)vp, off, (void *)phm);

			}
			ASSERT(MUTEX_HELD(phm));
			mutex_exit(phm);
			phm = NULL;

			/*
			 * Hat layer locking need not be done to set
			 * the following bits since the page is not hashed
			 * and was on the free list (i.e., had no mappings).
			 *
			 * Set the reference bit to protect
			 * against immediate pageout
			 *
			 * XXXmh modify freelist code to set reference
			 * bit so we don't have to do it here.
			 */
			page_set_props(pp, P_REF);
		} else {
			ASSERT(MUTEX_HELD(phm));
			mutex_exit(phm);
			phm = NULL;
			/*
			 * NOTE: This should not happen for pages associated
			 *	 with kernel vnode 'kvp'.
			 */
			/* XX64 - to debug why this happens! */
			ASSERT(!VN_ISKAS(vp));
			if (VN_ISKAS(vp))
				cmn_err(CE_NOTE,
				    "page_create: page not expected "
				    "in hash list for kernel vnode - pp 0x%p",
				    (void *)pp);
			VM_STAT_ADD(page_create_exists);
			goto fail;
		}

		/*
		 * Got a page!  It is locked.  Acquire the i/o
		 * lock since we are going to use the p_next and
		 * p_prev fields to link the requested pages together.
		 */
		page_io_lock(pp);
		page_add(&plist, pp);
		plist = plist->p_next;
		off += MMU_PAGESIZE;
		vaddr += MMU_PAGESIZE;
	}

	check_dma(mattr, plist, pages_req);
	return (plist);

fail:
	if (npp != NULL) {
		/*
		 * Did not need this page after all.
		 * Put it back on the free list.
		 */
		VM_STAT_ADD(page_create_putbacks);
		PP_SETFREE(npp);
		PP_SETAGED(npp);
		npp->p_offset = (u_offset_t)-1;
		page_list_add(npp, PG_FREE_LIST | PG_LIST_TAIL);
		page_unlock(npp);
	}

	/*
	 * Give up the pages we already got.
	 */
	while (plist != NULL) {
		pp = plist;
		page_sub(&plist, pp);
		page_io_unlock(pp);
		plist_len++;
		/*LINTED: constant in conditional ctx*/
		VN_DISPOSE(pp, B_INVAL, 0, kcred);
	}

	/*
	 * VN_DISPOSE does freemem accounting for the pages in plist
	 * by calling page_free. So, we need to undo the pcf accounting
	 * for only the remaining pages.
	 */
	VM_STAT_ADD(page_create_putbacks);
	page_create_putback(pages_req - plist_len);

	return (NULL);
}
#endif /* !__xpv */


/*
 * Copy the data from the physical page represented by "frompp" to
 * that represented by "topp". ppcopy uses CPU->cpu_caddr1 and
 * CPU->cpu_caddr2.  It assumes that no one uses either map at interrupt
 * level and no one sleeps with an active mapping there.
 *
 * Note that the ref/mod bits in the page_t's are not affected by
 * this operation, hence it is up to the caller to update them appropriately.
 */
int
ppcopy(page_t *frompp, page_t *topp)
{
	caddr_t		pp_addr1;
	caddr_t		pp_addr2;
	hat_mempte_t	pte1;
	hat_mempte_t	pte2;
	kmutex_t	*ppaddr_mutex;
	label_t		ljb;
	int		ret = 1;

	ASSERT_STACK_ALIGNED();
	ASSERT(PAGE_LOCKED(frompp));
	ASSERT(PAGE_LOCKED(topp));

	if (kpm_enable) {
		pp_addr1 = hat_kpm_page2va(frompp, 0);
		pp_addr2 = hat_kpm_page2va(topp, 0);
		kpreempt_disable();
	} else {
		/*
		 * disable pre-emption so that CPU can't change
		 */
		kpreempt_disable();

		pp_addr1 = CPU->cpu_caddr1;
		pp_addr2 = CPU->cpu_caddr2;
		pte1 = CPU->cpu_caddr1pte;
		pte2 = CPU->cpu_caddr2pte;

		ppaddr_mutex = &CPU->cpu_ppaddr_mutex;
		mutex_enter(ppaddr_mutex);

		hat_mempte_remap(page_pptonum(frompp), pp_addr1, pte1,
		    PROT_READ | HAT_STORECACHING_OK, HAT_LOAD_NOCONSIST);
		hat_mempte_remap(page_pptonum(topp), pp_addr2, pte2,
		    PROT_READ | PROT_WRITE | HAT_STORECACHING_OK,
		    HAT_LOAD_NOCONSIST);
	}

	if (on_fault(&ljb)) {
		ret = 0;
		goto faulted;
	}
	if (use_sse_pagecopy)
#ifdef __xpv
		page_copy_no_xmm(pp_addr2, pp_addr1);
#else
		hwblkpagecopy(pp_addr1, pp_addr2);
#endif
	else
		bcopy(pp_addr1, pp_addr2, PAGESIZE);

	no_fault();
faulted:
	if (!kpm_enable) {
#ifdef __xpv
		/*
		 * We can't leave unused mappings laying about under the
		 * hypervisor, so blow them away.
		 */
		if (HYPERVISOR_update_va_mapping((uintptr_t)pp_addr1, 0,
		    UVMF_INVLPG | UVMF_LOCAL) < 0)
			panic("HYPERVISOR_update_va_mapping() failed");
		if (HYPERVISOR_update_va_mapping((uintptr_t)pp_addr2, 0,
		    UVMF_INVLPG | UVMF_LOCAL) < 0)
			panic("HYPERVISOR_update_va_mapping() failed");
#endif
		mutex_exit(ppaddr_mutex);
	}
	kpreempt_enable();
	return (ret);
}

void
pagezero(page_t *pp, uint_t off, uint_t len)
{
	ASSERT(PAGE_LOCKED(pp));
	pfnzero(page_pptonum(pp), off, len);
}

/*
 * Zero the physical page from off to off + len given by pfn
 * without changing the reference and modified bits of page.
 *
 * We use this using CPU private page address #2, see ppcopy() for more info.
 * pfnzero() must not be called at interrupt level.
 */
void
pfnzero(pfn_t pfn, uint_t off, uint_t len)
{
	caddr_t		pp_addr2;
	hat_mempte_t	pte2;
	kmutex_t	*ppaddr_mutex = NULL;

	ASSERT_STACK_ALIGNED();
	ASSERT(len <= MMU_PAGESIZE);
	ASSERT(off <= MMU_PAGESIZE);
	ASSERT(off + len <= MMU_PAGESIZE);

	if (kpm_enable && !pfn_is_foreign(pfn)) {
		pp_addr2 = hat_kpm_pfn2va(pfn);
		kpreempt_disable();
	} else {
		kpreempt_disable();

		pp_addr2 = CPU->cpu_caddr2;
		pte2 = CPU->cpu_caddr2pte;

		ppaddr_mutex = &CPU->cpu_ppaddr_mutex;
		mutex_enter(ppaddr_mutex);

		hat_mempte_remap(pfn, pp_addr2, pte2,
		    PROT_READ | PROT_WRITE | HAT_STORECACHING_OK,
		    HAT_LOAD_NOCONSIST);
	}

	if (use_sse_pagezero) {
#ifdef __xpv
		uint_t rem;

		/*
		 * zero a byte at a time until properly aligned for
		 * block_zero_no_xmm().
		 */
		while (!P2NPHASE(off, ((uint_t)BLOCKZEROALIGN)) && len-- > 0)
			pp_addr2[off++] = 0;

		/*
		 * Now use faster block_zero_no_xmm() for any range
		 * that is properly aligned and sized.
		 */
		rem = P2PHASE(len, ((uint_t)BLOCKZEROALIGN));
		len -= rem;
		if (len != 0) {
			block_zero_no_xmm(pp_addr2 + off, len);
			off += len;
		}

		/*
		 * zero remainder with byte stores.
		 */
		while (rem-- > 0)
			pp_addr2[off++] = 0;
#else
		hwblkclr(pp_addr2 + off, len);
#endif
	} else {
		bzero(pp_addr2 + off, len);
	}

	if (!kpm_enable || pfn_is_foreign(pfn)) {
#ifdef __xpv
		/*
		 * On the hypervisor this page might get used for a page
		 * table before any intervening change to this mapping,
		 * so blow it away.
		 */
		if (HYPERVISOR_update_va_mapping((uintptr_t)pp_addr2, 0,
		    UVMF_INVLPG) < 0)
			panic("HYPERVISOR_update_va_mapping() failed");
#endif
		mutex_exit(ppaddr_mutex);
	}

	kpreempt_enable();
}

/*
 * Platform-dependent page scrub call.
 */
void
pagescrub(page_t *pp, uint_t off, uint_t len)
{
	/*
	 * For now, we rely on the fact that pagezero() will
	 * always clear UEs.
	 */
	pagezero(pp, off, len);
}

/*
 * set up two private addresses for use on a given CPU for use in ppcopy()
 */
void
setup_vaddr_for_ppcopy(struct cpu *cpup)
{
	void *addr;
	hat_mempte_t pte_pa;

	addr = vmem_alloc(heap_arena, mmu_ptob(1), VM_SLEEP);
	pte_pa = hat_mempte_setup(addr);
	cpup->cpu_caddr1 = addr;
	cpup->cpu_caddr1pte = pte_pa;

	addr = vmem_alloc(heap_arena, mmu_ptob(1), VM_SLEEP);
	pte_pa = hat_mempte_setup(addr);
	cpup->cpu_caddr2 = addr;
	cpup->cpu_caddr2pte = pte_pa;

	mutex_init(&cpup->cpu_ppaddr_mutex, NULL, MUTEX_DEFAULT, NULL);
}

/*
 * Undo setup_vaddr_for_ppcopy
 */
void
teardown_vaddr_for_ppcopy(struct cpu *cpup)
{
	mutex_destroy(&cpup->cpu_ppaddr_mutex);

	hat_mempte_release(cpup->cpu_caddr2, cpup->cpu_caddr2pte);
	cpup->cpu_caddr2pte = 0;
	vmem_free(heap_arena, cpup->cpu_caddr2, mmu_ptob(1));
	cpup->cpu_caddr2 = 0;

	hat_mempte_release(cpup->cpu_caddr1, cpup->cpu_caddr1pte);
	cpup->cpu_caddr1pte = 0;
	vmem_free(heap_arena, cpup->cpu_caddr1, mmu_ptob(1));
	cpup->cpu_caddr1 = 0;
}

/*
 * Function for flushing D-cache when performing module relocations
 * to an alternate mapping.  Unnecessary on Intel / AMD platforms.
 */
void
dcache_flushall()
{}

size_t
exec_get_spslew(void)
{
	return (0);
}

/*
 * Allocate a memory page.  The argument 'seed' can be any pseudo-random
 * number to vary where the pages come from.  This is quite a hacked up
 * method -- it works for now, but really needs to be fixed up a bit.
 *
 * We currently use page_create_va() on the kvp with fake offsets,
 * segments and virt address.  This is pretty bogus, but was copied from the
 * old hat_i86.c code.  A better approach would be to specify either mnode
 * random or mnode local and takes a page from whatever color has the MOST
 * available - this would have a minimal impact on page coloring.
 */
page_t *
page_get_physical(uintptr_t seed)
{
	page_t *pp;
	u_offset_t offset;
	static struct seg tmpseg;
	static uintptr_t ctr = 0;

	/*
	 * This code is gross, we really need a simpler page allocator.
	 *
	 * We need to assign an offset for the page to call page_create_va()
	 * To avoid conflicts with other pages, we get creative with the offset.
	 * For 32 bits, we need an offset > 4Gig
	 * For 64 bits, need an offset somewhere in the VA hole.
	 */
	offset = seed;
	if (offset > kernelbase)
		offset -= kernelbase;
	offset <<= MMU_PAGESHIFT;
#if defined(__amd64)
	offset += mmu.hole_start;	/* something in VA hole */
#else
	offset += 1ULL << 40;	/* something > 4 Gig */
#endif

	if (page_resv(1, KM_NOSLEEP) == 0)
		return (NULL);

#ifdef	DEBUG
	pp = page_exists(&kvp, offset);
	if (pp != NULL)
		panic("page already exists %p", (void *)pp);
#endif

	pp = page_create_va(&kvp, offset, MMU_PAGESIZE, PG_EXCL,
	    &tmpseg, (caddr_t)(ctr += MMU_PAGESIZE));	/* changing VA usage */
	if (pp != NULL) {
		page_io_unlock(pp);
		page_hashout(pp, NULL);
		page_downgrade(pp);
	}
	return (pp);
}