xref: /titanic_44/usr/src/uts/i86pc/os/mp_startup.c (revision 6918308b4f7a98b1ab7146af715a679a95b03288)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 #include <sys/types.h>
30 #include <sys/thread.h>
31 #include <sys/cpuvar.h>
32 #include <sys/t_lock.h>
33 #include <sys/param.h>
34 #include <sys/proc.h>
35 #include <sys/disp.h>
36 #include <sys/mmu.h>
37 #include <sys/class.h>
38 #include <sys/cmn_err.h>
39 #include <sys/debug.h>
40 #include <sys/asm_linkage.h>
41 #include <sys/x_call.h>
42 #include <sys/systm.h>
43 #include <sys/var.h>
44 #include <sys/vtrace.h>
45 #include <vm/hat.h>
46 #include <sys/mmu.h>
47 #include <vm/as.h>
48 #include <vm/seg_kmem.h>
49 #include <sys/segments.h>
50 #include <sys/kmem.h>
51 #include <sys/stack.h>
52 #include <sys/smp_impldefs.h>
53 #include <sys/x86_archext.h>
54 #include <sys/machsystm.h>
55 #include <sys/traptrace.h>
56 #include <sys/clock.h>
57 #include <sys/cpc_impl.h>
58 #include <sys/chip.h>
59 #include <sys/dtrace.h>
60 #include <sys/archsystm.h>
61 #include <sys/fp.h>
62 #include <sys/reboot.h>
63 #include <sys/kdi.h>
64 #include <vm/hat_i86.h>
65 #include <sys/memnode.h>
66 #include <sys/pci_cfgspace.h>
67 
68 struct cpu	cpus[1];			/* CPU data */
69 struct cpu	*cpu[NCPU] = {&cpus[0]};	/* pointers to all CPUs */
70 cpu_core_t	cpu_core[NCPU];			/* cpu_core structures */
71 
72 /*
73  * Useful for disabling MP bring-up for an MP capable kernel
74  * (a kernel that was built with MP defined)
75  */
76 int use_mp = 1;
77 
78 int mp_cpus = 0x1;	/* to be set by platform specific module	*/
79 
80 /*
81  * This variable is used by the hat layer to decide whether or not
82  * critical sections are needed to prevent race conditions.  For sun4m,
83  * this variable is set once enough MP initialization has been done in
84  * order to allow cross calls.
85  */
86 int flushes_require_xcalls = 0;
87 ulong_t	cpu_ready_set = 1;
88 
89 extern	void	real_mode_start(void);
90 extern	void	real_mode_end(void);
91 static 	void	mp_startup(void);
92 
93 static void cpu_sep_enable(void);
94 static void cpu_sep_disable(void);
95 static void cpu_asysc_enable(void);
96 static void cpu_asysc_disable(void);
97 
98 extern int tsc_gethrtime_enable;
99 
100 /*
101  * Init CPU info - get CPU type info for processor_info system call.
102  */
103 void
104 init_cpu_info(struct cpu *cp)
105 {
106 	processor_info_t *pi = &cp->cpu_type_info;
107 	char buf[CPU_IDSTRLEN];
108 
109 	/*
110 	 * Get clock-frequency property for the CPU.
111 	 */
112 	pi->pi_clock = cpu_freq;
113 
114 	(void) strcpy(pi->pi_processor_type, "i386");
115 	if (fpu_exists)
116 		(void) strcpy(pi->pi_fputypes, "i387 compatible");
117 
118 	(void) cpuid_getidstr(cp, buf, sizeof (buf));
119 
120 	cp->cpu_idstr = kmem_alloc(strlen(buf) + 1, KM_SLEEP);
121 	(void) strcpy(cp->cpu_idstr, buf);
122 
123 	cmn_err(CE_CONT, "?cpu%d: %s\n", cp->cpu_id, cp->cpu_idstr);
124 
125 	(void) cpuid_getbrandstr(cp, buf, sizeof (buf));
126 	cp->cpu_brandstr = kmem_alloc(strlen(buf) + 1, KM_SLEEP);
127 	(void) strcpy(cp->cpu_brandstr, buf);
128 
129 	cmn_err(CE_CONT, "?cpu%d: %s\n", cp->cpu_id, cp->cpu_brandstr);
130 }
131 
132 /*
133  * Configure syscall support on this CPU.
134  */
135 /*ARGSUSED*/
136 static void
137 init_cpu_syscall(struct cpu *cp)
138 {
139 	kpreempt_disable();
140 
141 #if defined(__amd64)
142 	if (x86_feature & X86_ASYSC) {
143 
144 #if !defined(__lint)
145 		/*
146 		 * The syscall instruction imposes a certain ordering on
147 		 * segment selectors, so we double-check that ordering
148 		 * here.
149 		 */
150 		ASSERT(KDS_SEL == KCS_SEL + 8);
151 		ASSERT(UDS_SEL == U32CS_SEL + 8);
152 		ASSERT(UCS_SEL == U32CS_SEL + 16);
153 #endif
154 		/*
155 		 * Turn syscall/sysret extensions on.
156 		 */
157 		cpu_asysc_enable();
158 
159 		/*
160 		 * Program the magic registers ..
161 		 */
162 		wrmsr(MSR_AMD_STAR, ((uint64_t)(U32CS_SEL << 16 | KCS_SEL)) <<
163 		    32);
164 		wrmsr(MSR_AMD_LSTAR, (uint64_t)(uintptr_t)sys_syscall);
165 		wrmsr(MSR_AMD_CSTAR, (uint64_t)(uintptr_t)sys_syscall32);
166 
167 		/*
168 		 * This list of flags is masked off the incoming
169 		 * %rfl when we enter the kernel.
170 		 */
171 		wrmsr(MSR_AMD_SFMASK, (uint64_t)(uintptr_t)(PS_IE | PS_T));
172 	}
173 #endif
174 
175 	/*
176 	 * On 32-bit kernels, we use sysenter/sysexit because it's too
177 	 * hard to use syscall/sysret, and it is more portable anyway.
178 	 *
179 	 * On 64-bit kernels on Nocona machines, the 32-bit syscall
180 	 * variant isn't available to 32-bit applications, but sysenter is.
181 	 */
182 	if (x86_feature & X86_SEP) {
183 
184 #if !defined(__lint)
185 		/*
186 		 * The sysenter instruction imposes a certain ordering on
187 		 * segment selectors, so we double-check that ordering
188 		 * here. See "sysenter" in Intel document 245471-012, "IA-32
189 		 * Intel Architecture Software Developer's Manual Volume 2:
190 		 * Instruction Set Reference"
191 		 */
192 		ASSERT(KDS_SEL == KCS_SEL + 8);
193 
194 		ASSERT32(UCS_SEL == ((KCS_SEL + 16) | 3));
195 		ASSERT32(UDS_SEL == UCS_SEL + 8);
196 
197 		ASSERT64(U32CS_SEL == ((KCS_SEL + 16) | 3));
198 		ASSERT64(UDS_SEL == U32CS_SEL + 8);
199 #endif
200 
201 		cpu_sep_enable();
202 
203 		/*
204 		 * resume() sets this value to the base of the threads stack
205 		 * via a context handler.
206 		 */
207 		wrmsr(MSR_INTC_SEP_ESP, 0ULL);
208 		wrmsr(MSR_INTC_SEP_EIP, (uint64_t)(uintptr_t)sys_sysenter);
209 	}
210 
211 	kpreempt_enable();
212 }
213 
214 /*
215  * Multiprocessor initialization.
216  *
217  * Allocate and initialize the cpu structure, TRAPTRACE buffer, and the
218  * startup and idle threads for the specified CPU.
219  */
220 static void
221 mp_startup_init(int cpun)
222 {
223 #if defined(__amd64)
224 extern void *long_mode_64(void);
225 #endif	/* __amd64 */
226 
227 	struct cpu *cp;
228 	struct tss *ntss;
229 	kthread_id_t tp;
230 	caddr_t	sp;
231 	int size;
232 	proc_t *procp;
233 	extern void idle();
234 	extern void init_intr_threads(struct cpu *);
235 
236 	struct cpu_tables *tablesp;
237 	rm_platter_t *real_mode_platter = (rm_platter_t *)rm_platter_va;
238 
239 #ifdef TRAPTRACE
240 	trap_trace_ctl_t *ttc = &trap_trace_ctl[cpun];
241 #endif
242 
243 	ASSERT(cpun < NCPU && cpu[cpun] == NULL);
244 
245 	if ((cp = kmem_zalloc(sizeof (*cp), KM_NOSLEEP)) == NULL) {
246 		panic("mp_startup_init: cpu%d: "
247 		    "no memory for cpu structure", cpun);
248 		/*NOTREACHED*/
249 	}
250 	procp = curthread->t_procp;
251 
252 	mutex_enter(&cpu_lock);
253 	/*
254 	 * Initialize the dispatcher first.
255 	 */
256 	disp_cpu_init(cp);
257 	mutex_exit(&cpu_lock);
258 
259 	cpu_vm_data_init(cp);
260 
261 	/*
262 	 * Allocate and initialize the startup thread for this CPU.
263 	 * Interrupt and process switch stacks get allocated later
264 	 * when the CPU starts running.
265 	 */
266 	tp = thread_create(NULL, 0, NULL, NULL, 0, procp,
267 	    TS_STOPPED, maxclsyspri);
268 
269 	/*
270 	 * Set state to TS_ONPROC since this thread will start running
271 	 * as soon as the CPU comes online.
272 	 *
273 	 * All the other fields of the thread structure are setup by
274 	 * thread_create().
275 	 */
276 	THREAD_ONPROC(tp, cp);
277 	tp->t_preempt = 1;
278 	tp->t_bound_cpu = cp;
279 	tp->t_affinitycnt = 1;
280 	tp->t_cpu = cp;
281 	tp->t_disp_queue = cp->cpu_disp;
282 
283 	/*
284 	 * Setup thread to start in mp_startup.
285 	 */
286 	sp = tp->t_stk;
287 	tp->t_pc = (uintptr_t)mp_startup;
288 	tp->t_sp = (uintptr_t)(sp - MINFRAME);
289 
290 	cp->cpu_id = cpun;
291 	cp->cpu_self = cp;
292 	cp->cpu_mask = 1 << cpun;
293 	cp->cpu_thread = tp;
294 	cp->cpu_lwp = NULL;
295 	cp->cpu_dispthread = tp;
296 	cp->cpu_dispatch_pri = DISP_PRIO(tp);
297 
298 	/*
299 	 * Now, initialize per-CPU idle thread for this CPU.
300 	 */
301 	tp = thread_create(NULL, PAGESIZE, idle, NULL, 0, procp, TS_ONPROC, -1);
302 
303 	cp->cpu_idle_thread = tp;
304 
305 	tp->t_preempt = 1;
306 	tp->t_bound_cpu = cp;
307 	tp->t_affinitycnt = 1;
308 	tp->t_cpu = cp;
309 	tp->t_disp_queue = cp->cpu_disp;
310 
311 	/*
312 	 * Bootstrap the CPU for CMT aware scheduling
313 	 * The rest of the initialization will happen from
314 	 * mp_startup()
315 	 */
316 	chip_bootstrap_cpu(cp);
317 
318 	/*
319 	 * Perform CPC intialization on the new CPU.
320 	 */
321 	kcpc_hw_init(cp);
322 
323 	/*
324 	 * Allocate virtual addresses for cpu_caddr1 and cpu_caddr2
325 	 * for each CPU.
326 	 */
327 
328 	setup_vaddr_for_ppcopy(cp);
329 
330 	/*
331 	 * Allocate space for page directory, stack, tss, gdt and idt.
332 	 * This assumes that kmem_alloc will return memory which is aligned
333 	 * to the next higher power of 2 or a page(if size > MAXABIG)
334 	 * If this assumption goes wrong at any time due to change in
335 	 * kmem alloc, things may not work as the page directory has to be
336 	 * page aligned
337 	 */
338 	if ((tablesp = kmem_zalloc(sizeof (*tablesp), KM_NOSLEEP)) == NULL)
339 		panic("mp_startup_init: cpu%d cannot allocate tables", cpun);
340 
341 	if ((uintptr_t)tablesp & ~MMU_STD_PAGEMASK) {
342 		kmem_free(tablesp, sizeof (struct cpu_tables));
343 		size = sizeof (struct cpu_tables) + MMU_STD_PAGESIZE;
344 		tablesp = kmem_zalloc(size, KM_NOSLEEP);
345 		tablesp = (struct cpu_tables *)
346 		    (((uintptr_t)tablesp + MMU_STD_PAGESIZE) &
347 		    MMU_STD_PAGEMASK);
348 	}
349 
350 	ntss = cp->cpu_tss = &tablesp->ct_tss;
351 	cp->cpu_gdt = tablesp->ct_gdt;
352 	bcopy(CPU->cpu_gdt, cp->cpu_gdt, NGDT * (sizeof (user_desc_t)));
353 
354 #if defined(__amd64)
355 
356 	/*
357 	 * #DF (double fault).
358 	 */
359 	ntss->tss_ist1 =
360 	    (uint64_t)&tablesp->ct_stack[sizeof (tablesp->ct_stack)];
361 
362 #elif defined(__i386)
363 
364 	ntss->tss_esp0 = ntss->tss_esp1 = ntss->tss_esp2 = ntss->tss_esp =
365 	    (uint32_t)&tablesp->ct_stack[sizeof (tablesp->ct_stack)];
366 
367 	ntss->tss_ss0 = ntss->tss_ss1 = ntss->tss_ss2 = ntss->tss_ss = KDS_SEL;
368 
369 	ntss->tss_eip = (uint32_t)mp_startup;
370 
371 	ntss->tss_cs = KCS_SEL;
372 	ntss->tss_fs = KFS_SEL;
373 	ntss->tss_gs = KGS_SEL;
374 
375 	/*
376 	 * setup kernel %gs.
377 	 */
378 	set_usegd(&cp->cpu_gdt[GDT_GS], cp, sizeof (struct cpu) -1, SDT_MEMRWA,
379 	    SEL_KPL, 0, 1);
380 
381 #endif	/* __i386 */
382 
383 	/*
384 	 * Set I/O bit map offset equal to size of TSS segment limit
385 	 * for no I/O permission map. This will cause all user I/O
386 	 * instructions to generate #gp fault.
387 	 */
388 	ntss->tss_bitmapbase = sizeof (*ntss);
389 
390 	/*
391 	 * setup kernel tss.
392 	 */
393 	set_syssegd((system_desc_t *)&cp->cpu_gdt[GDT_KTSS], cp->cpu_tss,
394 	    sizeof (*cp->cpu_tss) -1, SDT_SYSTSS, SEL_KPL);
395 
396 	/*
397 	 * If we have more than one node, each cpu gets a copy of IDT
398 	 * local to its node. If this is a Pentium box, we use cpu 0's
399 	 * IDT. cpu 0's IDT has been made read-only to workaround the
400 	 * cmpxchgl register bug
401 	 */
402 	cp->cpu_idt = CPU->cpu_idt;
403 	if (system_hardware.hd_nodes && x86_type != X86_TYPE_P5) {
404 		cp->cpu_idt = kmem_alloc(sizeof (idt0), KM_SLEEP);
405 		bcopy(idt0, cp->cpu_idt, sizeof (idt0));
406 	}
407 
408 	/*
409 	 * Get interrupt priority data from cpu 0
410 	 */
411 	cp->cpu_pri_data = CPU->cpu_pri_data;
412 
413 	hat_cpu_online(cp);
414 
415 	/* Should remove all entries for the current process/thread here */
416 
417 	/*
418 	 * Fill up the real mode platter to make it easy for real mode code to
419 	 * kick it off. This area should really be one passed by boot to kernel
420 	 * and guaranteed to be below 1MB and aligned to 16 bytes. Should also
421 	 * have identical physical and virtual address in paged mode.
422 	 */
423 	real_mode_platter->rm_idt_base = cp->cpu_idt;
424 	real_mode_platter->rm_idt_lim = sizeof (idt0) - 1;
425 	real_mode_platter->rm_gdt_base = cp->cpu_gdt;
426 	real_mode_platter->rm_gdt_lim = sizeof (gdt0) -1;
427 	real_mode_platter->rm_pdbr = getcr3();
428 	real_mode_platter->rm_cpu = cpun;
429 	real_mode_platter->rm_x86feature = x86_feature;
430 	real_mode_platter->rm_cr4 = cr4_value;
431 
432 #if defined(__amd64)
433 	if (getcr3() > 0xffffffffUL)
434 		panic("Cannot initialize CPUs; kernel's 64-bit page tables\n"
435 			"located above 4G in physical memory (@ 0x%llx).",
436 			(unsigned long long)getcr3());
437 
438 	/*
439 	 * Setup pseudo-descriptors for temporary GDT and IDT for use ONLY
440 	 * by code in real_mode_start():
441 	 *
442 	 * GDT[0]:  NULL selector
443 	 * GDT[1]:  64-bit CS: Long = 1, Present = 1, bits 12, 11 = 1
444 	 *
445 	 * Clear the IDT as interrupts will be off and a limit of 0 will cause
446 	 * the CPU to triple fault and reset on an NMI, seemingly as reasonable
447 	 * a course of action as any other, though it may cause the entire
448 	 * platform to reset in some cases...
449 	 */
450 	real_mode_platter->rm_temp_gdt[0] = 0ULL;
451 	real_mode_platter->rm_temp_gdt[TEMPGDT_KCODE64] = 0x20980000000000ULL;
452 
453 	real_mode_platter->rm_temp_gdt_lim = (ushort_t)
454 	    (sizeof (real_mode_platter->rm_temp_gdt) - 1);
455 	real_mode_platter->rm_temp_gdt_base = rm_platter_pa +
456 	    (uint32_t)(&((rm_platter_t *)0)->rm_temp_gdt);
457 
458 	real_mode_platter->rm_temp_idt_lim = 0;
459 	real_mode_platter->rm_temp_idt_base = 0;
460 
461 	/*
462 	 * Since the CPU needs to jump to protected mode using an identity
463 	 * mapped address, we need to calculate it here.
464 	 */
465 	real_mode_platter->rm_longmode64_addr = rm_platter_pa +
466 	    ((uint32_t)long_mode_64 - (uint32_t)real_mode_start);
467 #endif	/* __amd64 */
468 
469 #ifdef TRAPTRACE
470 	/*
471 	 * If this is a TRAPTRACE kernel, allocate TRAPTRACE buffers for this
472 	 * CPU.
473 	 */
474 	ttc->ttc_first = (uintptr_t)kmem_zalloc(trap_trace_bufsize, KM_SLEEP);
475 	ttc->ttc_next = ttc->ttc_first;
476 	ttc->ttc_limit = ttc->ttc_first + trap_trace_bufsize;
477 #endif
478 
479 	/*
480 	 * Record that we have another CPU.
481 	 */
482 	mutex_enter(&cpu_lock);
483 	/*
484 	 * Initialize the interrupt threads for this CPU
485 	 */
486 	init_intr_threads(cp);
487 	/*
488 	 * Add CPU to list of available CPUs.  It'll be on the active list
489 	 * after mp_startup().
490 	 */
491 	cpu_add_unit(cp);
492 	mutex_exit(&cpu_lock);
493 }
494 
495 /*
496  * Apply workarounds for known errata, and warn about those that are absent.
497  *
498  * System vendors occasionally create configurations which contain different
499  * revisions of the CPUs that are almost but not exactly the same.  At the
500  * time of writing, this meant that their clock rates were the same, their
501  * feature sets were the same, but the required workaround were -not-
502  * necessarily the same.  So, this routine is invoked on -every- CPU soon
503  * after starting to make sure that the resulting system contains the most
504  * pessimal set of workarounds needed to cope with *any* of the CPUs in the
505  * system.
506  *
507  * workaround_errata is invoked early in mlsetup() for CPU 0, and in
508  * mp_startup() for all slave CPUs. Slaves process workaround_errata prior
509  * to acknowledging their readiness to the master, so this routine will
510  * never be executed by multiple CPUs in parallel, thus making updates to
511  * global data safe.
512  *
513  * These workarounds are based on Rev 3.57 of the Revision Guide for
514  * AMD Athlon(tm) 64 and AMD Opteron(tm) Processors, August 2005.
515  */
516 
517 #if defined(OPTERON_ERRATUM_91)
518 int opteron_erratum_91;		/* if non-zero -> at least one cpu has it */
519 #endif
520 
521 #if defined(OPTERON_ERRATUM_93)
522 int opteron_erratum_93;		/* if non-zero -> at least one cpu has it */
523 #endif
524 
525 #if defined(OPTERON_ERRATUM_100)
526 int opteron_erratum_100;	/* if non-zero -> at least one cpu has it */
527 #endif
528 
529 #if defined(OPTERON_ERRATUM_109)
530 int opteron_erratum_109;	/* if non-zero -> at least one cpu has it */
531 #endif
532 
533 #if defined(OPTERON_ERRATUM_121)
534 int opteron_erratum_121;	/* if non-zero -> at least one cpu has it */
535 #endif
536 
537 #if defined(OPTERON_ERRATUM_122)
538 int opteron_erratum_122;	/* if non-zero -> at least one cpu has it */
539 #endif
540 
541 #if defined(OPTERON_ERRATUM_123)
542 int opteron_erratum_123;	/* if non-zero -> at least one cpu has it */
543 #endif
544 
545 #if defined(OPTERON_ERRATUM_131)
546 int opteron_erratum_131;	/* if non-zero -> at least one cpu has it */
547 #endif
548 
549 #if defined(OPTERON_WORKAROUND_6336786)
550 int opteron_workaround_6336786;	/* non-zero -> WA relevant and applied */
551 int opteron_workaround_6336786_UP = 0;	/* Not needed for UP */
552 #endif
553 
554 #define	WARNING(cpu, n)						\
555 	cmn_err(CE_WARN, "cpu%d: no workaround for erratum %d",	\
556 	    (cpu)->cpu_id, (n))
557 
558 uint_t
559 workaround_errata(struct cpu *cpu)
560 {
561 	uint_t missing = 0;
562 
563 	ASSERT(cpu == CPU);
564 
565 	/*LINTED*/
566 	if (cpuid_opteron_erratum(cpu, 88) > 0) {
567 		/*
568 		 * SWAPGS May Fail To Read Correct GS Base
569 		 */
570 #if defined(OPTERON_ERRATUM_88)
571 		/*
572 		 * The workaround is an mfence in the relevant assembler code
573 		 */
574 #else
575 		WARNING(cpu, 88);
576 		missing++;
577 #endif
578 	}
579 
580 	if (cpuid_opteron_erratum(cpu, 91) > 0) {
581 		/*
582 		 * Software Prefetches May Report A Page Fault
583 		 */
584 #if defined(OPTERON_ERRATUM_91)
585 		/*
586 		 * fix is in trap.c
587 		 */
588 		opteron_erratum_91++;
589 #else
590 		WARNING(cpu, 91);
591 		missing++;
592 #endif
593 	}
594 
595 	if (cpuid_opteron_erratum(cpu, 93) > 0) {
596 		/*
597 		 * RSM Auto-Halt Restart Returns to Incorrect RIP
598 		 */
599 #if defined(OPTERON_ERRATUM_93)
600 		/*
601 		 * fix is in trap.c
602 		 */
603 		opteron_erratum_93++;
604 #else
605 		WARNING(cpu, 93);
606 		missing++;
607 #endif
608 	}
609 
610 	/*LINTED*/
611 	if (cpuid_opteron_erratum(cpu, 95) > 0) {
612 		/*
613 		 * RET Instruction May Return to Incorrect EIP
614 		 */
615 #if defined(OPTERON_ERRATUM_95)
616 #if defined(_LP64)
617 		/*
618 		 * Workaround this by ensuring that 32-bit user code and
619 		 * 64-bit kernel code never occupy the same address
620 		 * range mod 4G.
621 		 */
622 		if (_userlimit32 > 0xc0000000ul)
623 			*(uintptr_t *)&_userlimit32 = 0xc0000000ul;
624 
625 		/*LINTED*/
626 		ASSERT((uint32_t)COREHEAP_BASE == 0xc0000000u);
627 #endif	/* _LP64 */
628 #else
629 		WARNING(cpu, 95);
630 		missing++;
631 #endif	/* OPTERON_ERRATUM_95 */
632 	}
633 
634 	if (cpuid_opteron_erratum(cpu, 100) > 0) {
635 		/*
636 		 * Compatibility Mode Branches Transfer to Illegal Address
637 		 */
638 #if defined(OPTERON_ERRATUM_100)
639 		/*
640 		 * fix is in trap.c
641 		 */
642 		opteron_erratum_100++;
643 #else
644 		WARNING(cpu, 100);
645 		missing++;
646 #endif
647 	}
648 
649 	/*LINTED*/
650 	if (cpuid_opteron_erratum(cpu, 108) > 0) {
651 		/*
652 		 * CPUID Instruction May Return Incorrect Model Number In
653 		 * Some Processors
654 		 */
655 #if defined(OPTERON_ERRATUM_108)
656 		/*
657 		 * (Our cpuid-handling code corrects the model number on
658 		 * those processors)
659 		 */
660 #else
661 		WARNING(cpu, 108);
662 		missing++;
663 #endif
664 	}
665 
666 	/*LINTED*/
667 	if (cpuid_opteron_erratum(cpu, 109) > 0) {
668 		/*
669 		 * Certain Reverse REP MOVS May Produce Unpredictable Behaviour
670 		 */
671 #if defined(OPTERON_ERRATUM_109)
672 
673 		/* workaround is to print a warning to upgrade BIOS */
674 		if (rdmsr(MSR_AMD_PATCHLEVEL) == 0)
675 			opteron_erratum_109++;
676 #else
677 		WARNING(cpu, 109);
678 		missing++;
679 #endif
680 	}
681 	/*LINTED*/
682 	if (cpuid_opteron_erratum(cpu, 121) > 0) {
683 		/*
684 		 * Sequential Execution Across Non_Canonical Boundary Caused
685 		 * Processor Hang
686 		 */
687 #if defined(OPTERON_ERRATUM_121)
688 		static int	lma;
689 
690 		if (opteron_erratum_121)
691 			opteron_erratum_121++;
692 
693 		/*
694 		 * Erratum 121 is only present in long (64 bit) mode.
695 		 * Workaround is to include the page immediately before the
696 		 * va hole to eliminate the possibility of system hangs due to
697 		 * sequential execution across the va hole boundary.
698 		 */
699 		if (lma == 0) {
700 			/*
701 			 * check LMA once: assume all cpus are in long mode
702 			 * or not.
703 			 */
704 			lma = 1;
705 
706 			if (rdmsr(MSR_AMD_EFER) & AMD_EFER_LMA) {
707 				if (hole_start) {
708 					hole_start -= PAGESIZE;
709 				} else {
710 					/*
711 					 * hole_start not yet initialized by
712 					 * mmu_init. Initialize hole_start
713 					 * with value to be subtracted.
714 					 */
715 					hole_start = PAGESIZE;
716 				}
717 				opteron_erratum_121++;
718 			}
719 		}
720 #else
721 		WARNING(cpu, 121);
722 		missing++;
723 #endif
724 	}
725 
726 	/*LINTED*/
727 	if (cpuid_opteron_erratum(cpu, 122) > 0) {
728 		/*
729 		 * TLB Flush Filter May Cause Cohenrency Problem in
730 		 * Multiprocessor Systems
731 		 */
732 #if defined(OPTERON_ERRATUM_122)
733 		/*
734 		 * Erratum 122 is only present in MP configurations (multi-core
735 		 * or multi-processor).
736 		 */
737 
738 		if (opteron_erratum_122 || lgrp_plat_node_cnt > 1 ||
739 		    cpuid_get_ncpu_per_chip(cpu) > 1) {
740 			/* disable TLB Flush Filter */
741 			wrmsr(MSR_AMD_HWCR, rdmsr(MSR_AMD_HWCR) |
742 			    (uint64_t)(uintptr_t)AMD_HWCR_FFDIS);
743 			opteron_erratum_122++;
744 		}
745 
746 #else
747 		WARNING(cpu, 122);
748 		missing++;
749 #endif
750 	}
751 
752 #if defined(OPTERON_ERRATUM_123)
753 	/*LINTED*/
754 	if (cpuid_opteron_erratum(cpu, 123) > 0) {
755 		/*
756 		 * Bypassed Reads May Cause Data Corruption of System Hang in
757 		 * Dual Core Processors
758 		 */
759 		/*
760 		 * Erratum 123 applies only to multi-core cpus.
761 		 */
762 
763 		if (cpuid_get_ncpu_per_chip(cpu) > 1) {
764 			/* workaround is to print a warning to upgrade BIOS */
765 			if (rdmsr(MSR_AMD_PATCHLEVEL) == 0)
766 				opteron_erratum_123++;
767 		}
768 	}
769 #endif
770 
771 #if defined(OPTERON_ERRATUM_131)
772 	/*LINTED*/
773 	if (cpuid_opteron_erratum(cpu, 131) > 0) {
774 		/*
775 		 * Multiprocessor Systems with Four or More Cores May Deadlock
776 		 * Waiting for a Probe Response
777 		 */
778 		/*
779 		 * Erratum 131 applies to any system with four or more cores.
780 		 */
781 		if ((opteron_erratum_131 == 0) && ((lgrp_plat_node_cnt *
782 		    cpuid_get_ncpu_per_chip(cpu)) >= 4)) {
783 			/*
784 			 * Workaround is to print a warning to upgrade
785 			 * the BIOS
786 			 */
787 			if (!(rdmsr(MSR_AMD_NB_CFG) & AMD_NB_CFG_SRQ_HEARTBEAT))
788 				opteron_erratum_131++;
789 		}
790 	}
791 #endif
792 
793 #if defined(OPTERON_WORKAROUND_6336786)
794 	/*
795 	 * This isn't really erratum, but for convenience the
796 	 * detection/workaround code lives here and in cpuid_opteron_erratum.
797 	 */
798 	if (cpuid_opteron_erratum(cpu, 6336786) > 0) {
799 		int	node;
800 		uint8_t data;
801 
802 		/*
803 		 * Disable C1-Clock ramping on multi-core/multi-processor
804 		 * K8 platforms to guard against TSC drift.
805 		 */
806 		if (opteron_workaround_6336786) {
807 			opteron_workaround_6336786++;
808 		} else if ((lgrp_plat_node_cnt *
809 		    cpuid_get_ncpu_per_chip(cpu) >= 2) ||
810 		    opteron_workaround_6336786_UP) {
811 			for (node = 0; node < lgrp_plat_node_cnt; node++) {
812 				/*
813 				 * Clear PMM7[1:0] (function 3, offset 0x87)
814 				 * Northbridge device is the node id + 24.
815 				 */
816 				data = pci_getb_func(0, node + 24, 3, 0x87);
817 				data &= 0xFC;
818 				pci_putb_func(0, node + 24, 3, 0x87, data);
819 			}
820 			opteron_workaround_6336786++;
821 		}
822 	}
823 #endif
824 	return (missing);
825 }
826 
827 void
828 workaround_errata_end()
829 {
830 #if defined(OPTERON_ERRATUM_109)
831 	if (opteron_erratum_109) {
832 		cmn_err(CE_WARN,
833 		    "BIOS microcode patch for AMD Athlon(tm) 64/Opteron(tm)"
834 		    " processor\nerratum 109 was not detected; updating your"
835 		    " system's BIOS to a version\ncontaining this"
836 		    " microcode patch is HIGHLY recommended or erroneous"
837 		    " system\noperation may occur.\n");
838 	}
839 #endif	/* OPTERON_ERRATUM_109 */
840 #if defined(OPTERON_ERRATUM_123)
841 	if (opteron_erratum_123) {
842 		cmn_err(CE_WARN,
843 		    "BIOS microcode patch for AMD Athlon(tm) 64/Opteron(tm)"
844 		    " processor\nerratum 123 was not detected; updating your"
845 		    " system's BIOS to a version\ncontaining this"
846 		    " microcode patch is HIGHLY recommended or erroneous"
847 		    " system\noperation may occur.\n");
848 	}
849 #endif	/* OPTERON_ERRATUM_123 */
850 #if defined(OPTERON_ERRATUM_131)
851 	if (opteron_erratum_131) {
852 		cmn_err(CE_WARN,
853 		    "BIOS microcode patch for AMD Athlon(tm) 64/Opteron(tm)"
854 		    " processor\nerratum 131 was not detected; updating your"
855 		    " system's BIOS to a version\ncontaining this"
856 		    " microcode patch is HIGHLY recommended or erroneous"
857 		    " system\noperation may occur.\n");
858 	}
859 #endif	/* OPTERON_ERRATUM_131 */
860 }
861 
862 static ushort_t *mp_map_warm_reset_vector();
863 static void mp_unmap_warm_reset_vector(ushort_t *warm_reset_vector);
864 
865 /*ARGSUSED*/
866 void
867 start_other_cpus(int cprboot)
868 {
869 	unsigned who;
870 	int cpuid = getbootcpuid();
871 	int delays = 0;
872 	int started_cpu;
873 	ushort_t *warm_reset_vector = NULL;
874 	extern int procset;
875 
876 	/*
877 	 * Initialize our own cpu_info.
878 	 */
879 	init_cpu_info(CPU);
880 
881 	/*
882 	 * Initialize our syscall handlers
883 	 */
884 	init_cpu_syscall(CPU);
885 
886 	/*
887 	 * if only 1 cpu or not using MP, skip the rest of this
888 	 */
889 	if (!(mp_cpus & ~(1 << cpuid)) || use_mp == 0) {
890 		if (use_mp == 0)
891 			cmn_err(CE_CONT, "?***** Not in MP mode\n");
892 		goto done;
893 	}
894 
895 	/*
896 	 * perform such initialization as is needed
897 	 * to be able to take CPUs on- and off-line.
898 	 */
899 	cpu_pause_init();
900 
901 	xc_init();		/* initialize processor crosscalls */
902 
903 	/*
904 	 * Copy the real mode code at "real_mode_start" to the
905 	 * page at rm_platter_va.
906 	 */
907 	warm_reset_vector = mp_map_warm_reset_vector();
908 	if (warm_reset_vector == NULL)
909 		goto done;
910 
911 	bcopy((caddr_t)real_mode_start,
912 	    (caddr_t)((rm_platter_t *)rm_platter_va)->rm_code,
913 	    (size_t)real_mode_end - (size_t)real_mode_start);
914 
915 	flushes_require_xcalls = 1;
916 
917 	affinity_set(CPU_CURRENT);
918 
919 	for (who = 0; who < NCPU; who++) {
920 		if (who == cpuid)
921 			continue;
922 
923 		if ((mp_cpus & (1 << who)) == 0)
924 			continue;
925 
926 		mp_startup_init(who);
927 		started_cpu = 1;
928 		(*cpu_startf)(who, rm_platter_pa);
929 
930 		while ((procset & (1 << who)) == 0) {
931 
932 			delay(1);
933 			if (++delays > (20 * hz)) {
934 
935 				cmn_err(CE_WARN,
936 				    "cpu%d failed to start", who);
937 
938 				mutex_enter(&cpu_lock);
939 				cpu[who]->cpu_flags = 0;
940 				cpu_vm_data_destroy(cpu[who]);
941 				cpu_del_unit(who);
942 				mutex_exit(&cpu_lock);
943 
944 				started_cpu = 0;
945 				break;
946 			}
947 		}
948 		if (!started_cpu)
949 			continue;
950 		if (tsc_gethrtime_enable)
951 			tsc_sync_master(who);
952 
953 
954 		if (dtrace_cpu_init != NULL) {
955 			/*
956 			 * DTrace CPU initialization expects cpu_lock
957 			 * to be held.
958 			 */
959 			mutex_enter(&cpu_lock);
960 			(*dtrace_cpu_init)(who);
961 			mutex_exit(&cpu_lock);
962 		}
963 	}
964 
965 	affinity_clear();
966 
967 	for (who = 0; who < NCPU; who++) {
968 		if (who == cpuid)
969 			continue;
970 
971 		if (!(procset & (1 << who)))
972 			continue;
973 
974 		while (!(cpu_ready_set & (1 << who)))
975 			delay(1);
976 	}
977 
978 done:
979 	workaround_errata_end();
980 
981 	if (warm_reset_vector != NULL)
982 		mp_unmap_warm_reset_vector(warm_reset_vector);
983 	hat_unload(kas.a_hat, (caddr_t)(uintptr_t)rm_platter_pa, MMU_PAGESIZE,
984 	    HAT_UNLOAD);
985 }
986 
987 /*
988  * Dummy functions - no i86pc platforms support dynamic cpu allocation.
989  */
990 /*ARGSUSED*/
991 int
992 mp_cpu_configure(int cpuid)
993 {
994 	return (ENOTSUP);		/* not supported */
995 }
996 
997 /*ARGSUSED*/
998 int
999 mp_cpu_unconfigure(int cpuid)
1000 {
1001 	return (ENOTSUP);		/* not supported */
1002 }
1003 
1004 /*
1005  * Startup function for 'other' CPUs (besides boot cpu).
1006  * Resumed from cpu_startup.
1007  */
1008 void
1009 mp_startup(void)
1010 {
1011 	struct cpu *cp = CPU;
1012 	extern int procset;
1013 	uint_t new_x86_feature;
1014 
1015 	new_x86_feature = cpuid_pass1(cp);
1016 
1017 	/*
1018 	 * We need to Sync MTRR with cpu0's MTRR. We have to do
1019 	 * this with interrupts disabled.
1020 	 */
1021 	if (x86_feature & X86_MTRR)
1022 		mtrr_sync();
1023 	/*
1024 	 * Enable machine check architecture
1025 	 */
1026 	if (x86_feature & X86_MCA)
1027 		setup_mca();
1028 
1029 	/*
1030 	 * Initialize this CPU's syscall handlers
1031 	 */
1032 	init_cpu_syscall(cp);
1033 
1034 	/*
1035 	 * Enable interrupts with spl set to LOCK_LEVEL. LOCK_LEVEL is the
1036 	 * highest level at which a routine is permitted to block on
1037 	 * an adaptive mutex (allows for cpu poke interrupt in case
1038 	 * the cpu is blocked on a mutex and halts). Setting LOCK_LEVEL blocks
1039 	 * device interrupts that may end up in the hat layer issuing cross
1040 	 * calls before CPU_READY is set.
1041 	 */
1042 	(void) splx(ipltospl(LOCK_LEVEL));
1043 
1044 	/*
1045 	 * Do a sanity check to make sure this new CPU is a sane thing
1046 	 * to add to the collection of processors running this system.
1047 	 *
1048 	 * XXX	Clearly this needs to get more sophisticated, if x86
1049 	 * systems start to get built out of heterogenous CPUs; as is
1050 	 * likely to happen once the number of processors in a configuration
1051 	 * gets large enough.
1052 	 */
1053 	if ((x86_feature & new_x86_feature) != x86_feature) {
1054 		cmn_err(CE_CONT, "?cpu%d: %b\n",
1055 		    cp->cpu_id, new_x86_feature, FMT_X86_FEATURE);
1056 		cmn_err(CE_WARN, "cpu%d feature mismatch", cp->cpu_id);
1057 	}
1058 
1059 	/*
1060 	 * We could be more sophisticated here, and just mark the CPU
1061 	 * as "faulted" but at this point we'll opt for the easier
1062 	 * answer of dieing horribly.  Provided the boot cpu is ok,
1063 	 * the system can be recovered by booting with use_mp set to zero.
1064 	 */
1065 	if (workaround_errata(cp) != 0)
1066 		panic("critical workaround(s) missing for cpu%d", cp->cpu_id);
1067 
1068 	cpuid_pass2(cp);
1069 	cpuid_pass3(cp);
1070 	(void) cpuid_pass4(cp);
1071 
1072 	init_cpu_info(cp);
1073 
1074 	add_cpunode2devtree(cp->cpu_id, cp->cpu_m.mcpu_cpi);
1075 
1076 	mutex_enter(&cpu_lock);
1077 	procset |= 1 << cp->cpu_id;
1078 	mutex_exit(&cpu_lock);
1079 
1080 	if (tsc_gethrtime_enable)
1081 		tsc_sync_slave();
1082 
1083 	mutex_enter(&cpu_lock);
1084 	/*
1085 	 * It's unfortunate that chip_cpu_init() has to be called here.
1086 	 * It really belongs in cpu_add_unit(), but unfortunately it is
1087 	 * dependent on the cpuid probing, which must be done in the
1088 	 * context of the current CPU. Care must be taken on x86 to ensure
1089 	 * that mp_startup can safely block even though chip_cpu_init() and
1090 	 * cpu_add_active() have not yet been called.
1091 	 */
1092 	chip_cpu_init(cp);
1093 	chip_cpu_startup(cp);
1094 
1095 	cp->cpu_flags |= CPU_RUNNING | CPU_READY | CPU_ENABLE | CPU_EXISTS;
1096 	cpu_add_active(cp);
1097 	mutex_exit(&cpu_lock);
1098 
1099 	(void) spl0();				/* enable interrupts */
1100 
1101 	if (boothowto & RB_DEBUG)
1102 		kdi_dvec_cpu_init(cp);
1103 
1104 	/*
1105 	 * Setting the bit in cpu_ready_set must be the last operation in
1106 	 * processor initialization; the boot CPU will continue to boot once
1107 	 * it sees this bit set for all active CPUs.
1108 	 */
1109 	CPUSET_ATOMIC_ADD(cpu_ready_set, cp->cpu_id);
1110 
1111 	/*
1112 	 * Because mp_startup() gets fired off after init() starts, we
1113 	 * can't use the '?' trick to do 'boot -v' printing - so we
1114 	 * always direct the 'cpu .. online' messages to the log.
1115 	 */
1116 	cmn_err(CE_CONT, "!cpu%d initialization complete - online\n",
1117 	    cp->cpu_id);
1118 
1119 	/*
1120 	 * Now we are done with the startup thread, so free it up.
1121 	 */
1122 	thread_exit();
1123 	panic("mp_startup: cannot return");
1124 	/*NOTREACHED*/
1125 }
1126 
1127 
1128 /*
1129  * Start CPU on user request.
1130  */
1131 /* ARGSUSED */
1132 int
1133 mp_cpu_start(struct cpu *cp)
1134 {
1135 	ASSERT(MUTEX_HELD(&cpu_lock));
1136 	if (cp->cpu_id == getbootcpuid())
1137 		return (EBUSY); 	/* Cannot start boot CPU */
1138 	return (0);
1139 }
1140 
1141 /*
1142  * Stop CPU on user request.
1143  */
1144 /* ARGSUSED */
1145 int
1146 mp_cpu_stop(struct cpu *cp)
1147 {
1148 	ASSERT(MUTEX_HELD(&cpu_lock));
1149 	if (cp->cpu_id == getbootcpuid())
1150 		return (EBUSY); 	/* Cannot stop boot CPU */
1151 
1152 	return (0);
1153 }
1154 
1155 /*
1156  * Power on CPU.
1157  */
1158 /* ARGSUSED */
1159 int
1160 mp_cpu_poweron(struct cpu *cp)
1161 {
1162 	ASSERT(MUTEX_HELD(&cpu_lock));
1163 	return (ENOTSUP);		/* not supported */
1164 }
1165 
1166 /*
1167  * Power off CPU.
1168  */
1169 /* ARGSUSED */
1170 int
1171 mp_cpu_poweroff(struct cpu *cp)
1172 {
1173 	ASSERT(MUTEX_HELD(&cpu_lock));
1174 	return (ENOTSUP);		/* not supported */
1175 }
1176 
1177 
1178 /*
1179  * Take the specified CPU out of participation in interrupts.
1180  */
1181 int
1182 cpu_disable_intr(struct cpu *cp)
1183 {
1184 	/*
1185 	 * cannot disable interrupts on boot cpu
1186 	 */
1187 	if (cp == cpu[getbootcpuid()])
1188 		return (EBUSY);
1189 
1190 	if (psm_disable_intr(cp->cpu_id) != DDI_SUCCESS)
1191 		return (EBUSY);
1192 
1193 	cp->cpu_flags &= ~CPU_ENABLE;
1194 	return (0);
1195 }
1196 
1197 /*
1198  * Allow the specified CPU to participate in interrupts.
1199  */
1200 void
1201 cpu_enable_intr(struct cpu *cp)
1202 {
1203 	ASSERT(MUTEX_HELD(&cpu_lock));
1204 	if (cp == cpu[getbootcpuid()])
1205 		return;
1206 
1207 	cp->cpu_flags |= CPU_ENABLE;
1208 	psm_enable_intr(cp->cpu_id);
1209 }
1210 
1211 
1212 /*
1213  * return the cpu id of the initial startup cpu
1214  */
1215 processorid_t
1216 getbootcpuid(void)
1217 {
1218 	return (0);
1219 }
1220 
1221 static ushort_t *
1222 mp_map_warm_reset_vector()
1223 {
1224 	ushort_t *warm_reset_vector;
1225 
1226 	if (!(warm_reset_vector = (ushort_t *)psm_map_phys(WARM_RESET_VECTOR,
1227 	    sizeof (ushort_t *), PROT_READ|PROT_WRITE)))
1228 		return (NULL);
1229 
1230 	/*
1231 	 * setup secondary cpu bios boot up vector
1232 	 */
1233 	*warm_reset_vector = (ushort_t)((caddr_t)
1234 		((struct rm_platter *)rm_platter_va)->rm_code - rm_platter_va
1235 		+ ((ulong_t)rm_platter_va & 0xf));
1236 	warm_reset_vector++;
1237 	*warm_reset_vector = (ushort_t)(rm_platter_pa >> 4);
1238 
1239 	--warm_reset_vector;
1240 	return (warm_reset_vector);
1241 }
1242 
1243 static void
1244 mp_unmap_warm_reset_vector(ushort_t *warm_reset_vector)
1245 {
1246 	psm_unmap_phys((caddr_t)warm_reset_vector, sizeof (ushort_t *));
1247 }
1248 
1249 /*ARGSUSED*/
1250 void
1251 mp_cpu_faulted_enter(struct cpu *cp)
1252 {}
1253 
1254 /*ARGSUSED*/
1255 void
1256 mp_cpu_faulted_exit(struct cpu *cp)
1257 {}
1258 
1259 /*
1260  * The following two routines are used as context operators on threads belonging
1261  * to processes with a private LDT (see sysi86).  Due to the rarity of such
1262  * processes, these routines are currently written for best code readability and
1263  * organization rather than speed.  We could avoid checking x86_feature at every
1264  * context switch by installing different context ops, depending on the
1265  * x86_feature flags, at LDT creation time -- one for each combination of fast
1266  * syscall feature flags.
1267  */
1268 
1269 /*ARGSUSED*/
1270 void
1271 cpu_fast_syscall_disable(void *arg)
1272 {
1273 	if (x86_feature & X86_SEP)
1274 		cpu_sep_disable();
1275 	if (x86_feature & X86_ASYSC)
1276 		cpu_asysc_disable();
1277 }
1278 
1279 /*ARGSUSED*/
1280 void
1281 cpu_fast_syscall_enable(void *arg)
1282 {
1283 	if (x86_feature & X86_SEP)
1284 		cpu_sep_enable();
1285 	if (x86_feature & X86_ASYSC)
1286 		cpu_asysc_enable();
1287 }
1288 
1289 static void
1290 cpu_sep_enable(void)
1291 {
1292 	ASSERT(x86_feature & X86_SEP);
1293 	ASSERT(curthread->t_preempt || getpil() >= LOCK_LEVEL);
1294 
1295 	wrmsr(MSR_INTC_SEP_CS, (uint64_t)(uintptr_t)KCS_SEL);
1296 }
1297 
1298 static void
1299 cpu_sep_disable(void)
1300 {
1301 	ASSERT(x86_feature & X86_SEP);
1302 	ASSERT(curthread->t_preempt || getpil() >= LOCK_LEVEL);
1303 
1304 	/*
1305 	 * Setting the SYSENTER_CS_MSR register to 0 causes software executing
1306 	 * the sysenter or sysexit instruction to trigger a #gp fault.
1307 	 */
1308 	wrmsr(MSR_INTC_SEP_CS, 0ULL);
1309 }
1310 
1311 static void
1312 cpu_asysc_enable(void)
1313 {
1314 	ASSERT(x86_feature & X86_ASYSC);
1315 	ASSERT(curthread->t_preempt || getpil() >= LOCK_LEVEL);
1316 
1317 	wrmsr(MSR_AMD_EFER, rdmsr(MSR_AMD_EFER) |
1318 	    (uint64_t)(uintptr_t)AMD_EFER_SCE);
1319 }
1320 
1321 static void
1322 cpu_asysc_disable(void)
1323 {
1324 	ASSERT(x86_feature & X86_ASYSC);
1325 	ASSERT(curthread->t_preempt || getpil() >= LOCK_LEVEL);
1326 
1327 	/*
1328 	 * Turn off the SCE (syscall enable) bit in the EFER register. Software
1329 	 * executing syscall or sysret with this bit off will incur a #ud trap.
1330 	 */
1331 	wrmsr(MSR_AMD_EFER, rdmsr(MSR_AMD_EFER) &
1332 	    ~((uint64_t)(uintptr_t)AMD_EFER_SCE));
1333 }
1334