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/segment.h> 15#include <asm/asm.h> 16#include <asm/boot.h> 17#include <asm/processor-flags.h> 18#include <asm/msr.h> 19#include <asm/nospec-branch.h> 20#include <xen/interface/elfnote.h> 21 22 __HEAD 23 24/* 25 * Entry point for PVH guests. 26 * 27 * Xen ABI specifies the following register state when we come here: 28 * 29 * - `ebx`: contains the physical memory address where the loader has placed 30 * the boot start info structure. 31 * - `cr0`: bit 0 (PE) must be set. All the other writeable bits are cleared. 32 * - `cr4`: all bits are cleared. 33 * - `cs `: must be a 32-bit read/execute code segment with a base of `0` 34 * and a limit of `0xFFFFFFFF`. The selector value is unspecified. 35 * - `ds`, `es`: must be a 32-bit read/write data segment with a base of 36 * `0` and a limit of `0xFFFFFFFF`. The selector values are all 37 * unspecified. 38 * - `tr`: must be a 32-bit TSS (active) with a base of '0' and a limit 39 * of '0x67'. 40 * - `eflags`: bit 17 (VM) must be cleared. Bit 9 (IF) must be cleared. 41 * Bit 8 (TF) must be cleared. Other bits are all unspecified. 42 * 43 * All other processor registers and flag bits are unspecified. The OS is in 44 * charge of setting up it's own stack, GDT and IDT. 45 */ 46 47#define PVH_GDT_ENTRY_CS 1 48#define PVH_GDT_ENTRY_DS 2 49#define PVH_CS_SEL (PVH_GDT_ENTRY_CS * 8) 50#define PVH_DS_SEL (PVH_GDT_ENTRY_DS * 8) 51 52SYM_CODE_START_LOCAL(pvh_start_xen) 53 cld 54 55 lgdt (_pa(gdt)) 56 57 mov $PVH_DS_SEL,%eax 58 mov %eax,%ds 59 mov %eax,%es 60 mov %eax,%ss 61 62 /* Stash hvm_start_info. */ 63 mov $_pa(pvh_start_info), %edi 64 mov %ebx, %esi 65 mov _pa(pvh_start_info_sz), %ecx 66 shr $2,%ecx 67 rep 68 movsl 69 70 mov $_pa(early_stack_end), %esp 71 72 /* Enable PAE mode. */ 73 mov %cr4, %eax 74 orl $X86_CR4_PAE, %eax 75 mov %eax, %cr4 76 77#ifdef CONFIG_X86_64 78 /* Enable Long mode. */ 79 mov $MSR_EFER, %ecx 80 rdmsr 81 btsl $_EFER_LME, %eax 82 wrmsr 83 84 /* Enable pre-constructed page tables. */ 85 mov $_pa(init_top_pgt), %eax 86 mov %eax, %cr3 87 mov $(X86_CR0_PG | X86_CR0_PE), %eax 88 mov %eax, %cr0 89 90 /* Jump to 64-bit mode. */ 91 ljmp $PVH_CS_SEL, $_pa(1f) 92 93 /* 64-bit entry point. */ 94 .code64 951: 96 /* Set base address in stack canary descriptor. */ 97 mov $MSR_GS_BASE,%ecx 98 mov $_pa(canary), %eax 99 xor %edx, %edx 100 wrmsr 101 102 call xen_prepare_pvh 103 104 /* startup_64 expects boot_params in %rsi. */ 105 mov $_pa(pvh_bootparams), %rsi 106 mov $_pa(startup_64), %rax 107 ANNOTATE_RETPOLINE_SAFE 108 jmp *%rax 109 110#else /* CONFIG_X86_64 */ 111 112 call mk_early_pgtbl_32 113 114 mov $_pa(initial_page_table), %eax 115 mov %eax, %cr3 116 117 mov %cr0, %eax 118 or $(X86_CR0_PG | X86_CR0_PE), %eax 119 mov %eax, %cr0 120 121 ljmp $PVH_CS_SEL, $1f 1221: 123 call xen_prepare_pvh 124 mov $_pa(pvh_bootparams), %esi 125 126 /* startup_32 doesn't expect paging and PAE to be on. */ 127 ljmp $PVH_CS_SEL, $_pa(2f) 1282: 129 mov %cr0, %eax 130 and $~X86_CR0_PG, %eax 131 mov %eax, %cr0 132 mov %cr4, %eax 133 and $~X86_CR4_PAE, %eax 134 mov %eax, %cr4 135 136 ljmp $PVH_CS_SEL, $_pa(startup_32) 137#endif 138SYM_CODE_END(pvh_start_xen) 139 140 .section ".init.data","aw" 141 .balign 8 142SYM_DATA_START_LOCAL(gdt) 143 .word gdt_end - gdt_start 144 .long _pa(gdt_start) 145 .word 0 146SYM_DATA_END(gdt) 147SYM_DATA_START_LOCAL(gdt_start) 148 .quad 0x0000000000000000 /* NULL descriptor */ 149#ifdef CONFIG_X86_64 150 .quad GDT_ENTRY(0xa09a, 0, 0xfffff) /* PVH_CS_SEL */ 151#else 152 .quad GDT_ENTRY(0xc09a, 0, 0xfffff) /* PVH_CS_SEL */ 153#endif 154 .quad GDT_ENTRY(0xc092, 0, 0xfffff) /* PVH_DS_SEL */ 155SYM_DATA_END_LABEL(gdt_start, SYM_L_LOCAL, gdt_end) 156 157 .balign 16 158SYM_DATA_LOCAL(canary, .fill 48, 1, 0) 159 160SYM_DATA_START_LOCAL(early_stack) 161 .fill BOOT_STACK_SIZE, 1, 0 162SYM_DATA_END_LABEL(early_stack, SYM_L_LOCAL, early_stack_end) 163 164 ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY, 165 _ASM_PTR (pvh_start_xen - __START_KERNEL_map)) 166