1/* SPDX-License-Identifier: GPL-2.0 */ 2 3/* 4 * Copyright C 2016, Oracle and/or its affiliates. All rights reserved. 5 */ 6 7 .code32 8 .text 9#define _pa(x) ((x) - __START_KERNEL_map) 10 11#include <linux/elfnote.h> 12#include <linux/init.h> 13#include <linux/linkage.h> 14#include <asm/desc_defs.h> 15#include <asm/segment.h> 16#include <asm/asm.h> 17#include <asm/boot.h> 18#include <asm/processor-flags.h> 19#include <asm/msr.h> 20#include <asm/nospec-branch.h> 21#include <xen/interface/elfnote.h> 22 23 __HEAD 24 25/* 26 * Entry point for PVH guests. 27 * 28 * Xen ABI specifies the following register state when we come here: 29 * 30 * - `ebx`: contains the physical memory address where the loader has placed 31 * the boot start info structure. 32 * - `cr0`: bit 0 (PE) must be set. All the other writeable bits are cleared. 33 * - `cr4`: all bits are cleared. 34 * - `cs `: must be a 32-bit read/execute code segment with a base of `0` 35 * and a limit of `0xFFFFFFFF`. The selector value is unspecified. 36 * - `ds`, `es`: must be a 32-bit read/write data segment with a base of 37 * `0` and a limit of `0xFFFFFFFF`. The selector values are all 38 * unspecified. 39 * - `tr`: must be a 32-bit TSS (active) with a base of '0' and a limit 40 * of '0x67'. 41 * - `eflags`: bit 17 (VM) must be cleared. Bit 9 (IF) must be cleared. 42 * Bit 8 (TF) must be cleared. Other bits are all unspecified. 43 * 44 * All other processor registers and flag bits are unspecified. The OS is in 45 * charge of setting up its own stack, GDT and IDT. 46 */ 47 48#define PVH_GDT_ENTRY_CS 1 49#define PVH_GDT_ENTRY_DS 2 50#define PVH_CS_SEL (PVH_GDT_ENTRY_CS * 8) 51#define PVH_DS_SEL (PVH_GDT_ENTRY_DS * 8) 52 53SYM_CODE_START_LOCAL(pvh_start_xen) 54 UNWIND_HINT_END_OF_STACK 55 cld 56 57 lgdt (_pa(gdt)) 58 59 mov $PVH_DS_SEL,%eax 60 mov %eax,%ds 61 mov %eax,%es 62 mov %eax,%ss 63 64 /* Stash hvm_start_info. */ 65 mov $_pa(pvh_start_info), %edi 66 mov %ebx, %esi 67 mov _pa(pvh_start_info_sz), %ecx 68 shr $2,%ecx 69 rep 70 movsl 71 72 mov $_pa(early_stack_end), %esp 73 74 /* Enable PAE mode. */ 75 mov %cr4, %eax 76 orl $X86_CR4_PAE, %eax 77 mov %eax, %cr4 78 79#ifdef CONFIG_X86_64 80 /* Enable Long mode. */ 81 mov $MSR_EFER, %ecx 82 rdmsr 83 btsl $_EFER_LME, %eax 84 wrmsr 85 86 /* Enable pre-constructed page tables. */ 87 mov $_pa(init_top_pgt), %eax 88 mov %eax, %cr3 89 mov $(X86_CR0_PG | X86_CR0_PE), %eax 90 mov %eax, %cr0 91 92 /* Jump to 64-bit mode. */ 93 ljmp $PVH_CS_SEL, $_pa(1f) 94 95 /* 64-bit entry point. */ 96 .code64 971: 98 /* Set base address in stack canary descriptor. */ 99 mov $MSR_GS_BASE,%ecx 100 mov $_pa(canary), %eax 101 xor %edx, %edx 102 wrmsr 103 104 call xen_prepare_pvh 105 106 /* startup_64 expects boot_params in %rsi. */ 107 mov $_pa(pvh_bootparams), %rsi 108 mov $_pa(startup_64), %rax 109 ANNOTATE_RETPOLINE_SAFE 110 jmp *%rax 111 112#else /* CONFIG_X86_64 */ 113 114 call mk_early_pgtbl_32 115 116 mov $_pa(initial_page_table), %eax 117 mov %eax, %cr3 118 119 mov %cr0, %eax 120 or $(X86_CR0_PG | X86_CR0_PE), %eax 121 mov %eax, %cr0 122 123 ljmp $PVH_CS_SEL, $1f 1241: 125 call xen_prepare_pvh 126 mov $_pa(pvh_bootparams), %esi 127 128 /* startup_32 doesn't expect paging and PAE to be on. */ 129 ljmp $PVH_CS_SEL, $_pa(2f) 1302: 131 mov %cr0, %eax 132 and $~X86_CR0_PG, %eax 133 mov %eax, %cr0 134 mov %cr4, %eax 135 and $~X86_CR4_PAE, %eax 136 mov %eax, %cr4 137 138 ljmp $PVH_CS_SEL, $_pa(startup_32) 139#endif 140SYM_CODE_END(pvh_start_xen) 141 142 .section ".init.data","aw" 143 .balign 8 144SYM_DATA_START_LOCAL(gdt) 145 .word gdt_end - gdt_start 146 .long _pa(gdt_start) 147 .word 0 148SYM_DATA_END(gdt) 149SYM_DATA_START_LOCAL(gdt_start) 150 .quad 0x0000000000000000 /* NULL descriptor */ 151#ifdef CONFIG_X86_64 152 .quad GDT_ENTRY(DESC_CODE64, 0, 0xfffff) /* PVH_CS_SEL */ 153#else 154 .quad GDT_ENTRY(DESC_CODE32, 0, 0xfffff) /* PVH_CS_SEL */ 155#endif 156 .quad GDT_ENTRY(DESC_DATA32, 0, 0xfffff) /* PVH_DS_SEL */ 157SYM_DATA_END_LABEL(gdt_start, SYM_L_LOCAL, gdt_end) 158 159 .balign 16 160SYM_DATA_LOCAL(canary, .fill 48, 1, 0) 161 162SYM_DATA_START_LOCAL(early_stack) 163 .fill BOOT_STACK_SIZE, 1, 0 164SYM_DATA_END_LABEL(early_stack, SYM_L_LOCAL, early_stack_end) 165 166 ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY, 167 _ASM_PTR (pvh_start_xen - __START_KERNEL_map)) 168