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 <xen/interface/elfnote.h> 20 21 __HEAD 22 23/* 24 * Entry point for PVH guests. 25 * 26 * Xen ABI specifies the following register state when we come here: 27 * 28 * - `ebx`: contains the physical memory address where the loader has placed 29 * the boot start info structure. 30 * - `cr0`: bit 0 (PE) must be set. All the other writeable bits are cleared. 31 * - `cr4`: all bits are cleared. 32 * - `cs `: must be a 32-bit read/execute code segment with a base of ‘0’ 33 * and a limit of ‘0xFFFFFFFF’. The selector value is unspecified. 34 * - `ds`, `es`: must be a 32-bit read/write data segment with a base of 35 * ‘0’ and a limit of ‘0xFFFFFFFF’. The selector values are all 36 * unspecified. 37 * - `tr`: must be a 32-bit TSS (active) with a base of '0' and a limit 38 * of '0x67'. 39 * - `eflags`: bit 17 (VM) must be cleared. Bit 9 (IF) must be cleared. 40 * Bit 8 (TF) must be cleared. Other bits are all unspecified. 41 * 42 * All other processor registers and flag bits are unspecified. The OS is in 43 * charge of setting up it's own stack, GDT and IDT. 44 */ 45 46#define PVH_GDT_ENTRY_CS 1 47#define PVH_GDT_ENTRY_DS 2 48#define PVH_GDT_ENTRY_CANARY 3 49#define PVH_CS_SEL (PVH_GDT_ENTRY_CS * 8) 50#define PVH_DS_SEL (PVH_GDT_ENTRY_DS * 8) 51#define PVH_CANARY_SEL (PVH_GDT_ENTRY_CANARY * 8) 52 53ENTRY(pvh_start_xen) 54 cld 55 56 lgdt (_pa(gdt)) 57 58 mov $PVH_DS_SEL,%eax 59 mov %eax,%ds 60 mov %eax,%es 61 mov %eax,%ss 62 63 /* Stash hvm_start_info. */ 64 mov $_pa(pvh_start_info), %edi 65 mov %ebx, %esi 66 mov _pa(pvh_start_info_sz), %ecx 67 shr $2,%ecx 68 rep 69 movsl 70 71 mov $_pa(early_stack_end), %esp 72 73 /* Enable PAE mode. */ 74 mov %cr4, %eax 75 orl $X86_CR4_PAE, %eax 76 mov %eax, %cr4 77 78#ifdef CONFIG_X86_64 79 /* Enable Long mode. */ 80 mov $MSR_EFER, %ecx 81 rdmsr 82 btsl $_EFER_LME, %eax 83 wrmsr 84 85 /* Enable pre-constructed page tables. */ 86 mov $_pa(init_top_pgt), %eax 87 mov %eax, %cr3 88 mov $(X86_CR0_PG | X86_CR0_PE), %eax 89 mov %eax, %cr0 90 91 /* Jump to 64-bit mode. */ 92 ljmp $PVH_CS_SEL, $_pa(1f) 93 94 /* 64-bit entry point. */ 95 .code64 961: 97 /* Set base address in stack canary descriptor. */ 98 mov $MSR_GS_BASE,%ecx 99 mov $_pa(canary), %eax 100 xor %edx, %edx 101 wrmsr 102 103 call xen_prepare_pvh 104 105 /* startup_64 expects boot_params in %rsi. */ 106 mov $_pa(pvh_bootparams), %rsi 107 mov $_pa(startup_64), %rax 108 jmp *%rax 109 110#else /* CONFIG_X86_64 */ 111 112 /* Set base address in stack canary descriptor. */ 113 movl $_pa(gdt_start),%eax 114 movl $_pa(canary),%ecx 115 movw %cx, (PVH_GDT_ENTRY_CANARY * 8) + 2(%eax) 116 shrl $16, %ecx 117 movb %cl, (PVH_GDT_ENTRY_CANARY * 8) + 4(%eax) 118 movb %ch, (PVH_GDT_ENTRY_CANARY * 8) + 7(%eax) 119 120 mov $PVH_CANARY_SEL,%eax 121 mov %eax,%gs 122 123 call mk_early_pgtbl_32 124 125 mov $_pa(initial_page_table), %eax 126 mov %eax, %cr3 127 128 mov %cr0, %eax 129 or $(X86_CR0_PG | X86_CR0_PE), %eax 130 mov %eax, %cr0 131 132 ljmp $PVH_CS_SEL, $1f 1331: 134 call xen_prepare_pvh 135 mov $_pa(pvh_bootparams), %esi 136 137 /* startup_32 doesn't expect paging and PAE to be on. */ 138 ljmp $PVH_CS_SEL, $_pa(2f) 1392: 140 mov %cr0, %eax 141 and $~X86_CR0_PG, %eax 142 mov %eax, %cr0 143 mov %cr4, %eax 144 and $~X86_CR4_PAE, %eax 145 mov %eax, %cr4 146 147 ljmp $PVH_CS_SEL, $_pa(startup_32) 148#endif 149END(pvh_start_xen) 150 151 .section ".init.data","aw" 152 .balign 8 153gdt: 154 .word gdt_end - gdt_start 155 .long _pa(gdt_start) 156 .word 0 157gdt_start: 158 .quad 0x0000000000000000 /* NULL descriptor */ 159#ifdef CONFIG_X86_64 160 .quad GDT_ENTRY(0xa09a, 0, 0xfffff) /* PVH_CS_SEL */ 161#else 162 .quad GDT_ENTRY(0xc09a, 0, 0xfffff) /* PVH_CS_SEL */ 163#endif 164 .quad GDT_ENTRY(0xc092, 0, 0xfffff) /* PVH_DS_SEL */ 165 .quad GDT_ENTRY(0x4090, 0, 0x18) /* PVH_CANARY_SEL */ 166gdt_end: 167 168 .balign 16 169canary: 170 .fill 48, 1, 0 171 172early_stack: 173 .fill BOOT_STACK_SIZE, 1, 0 174early_stack_end: 175 176 ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY, 177 _ASM_PTR (pvh_start_xen - __START_KERNEL_map)) 178