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Diffstat (limited to 'arch/x86/platform/pvh/head.S')
| -rw-r--r-- | arch/x86/platform/pvh/head.S | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/arch/x86/platform/pvh/head.S b/arch/x86/platform/pvh/head.S new file mode 100644 index 000000000000..1f8825bbaffb --- /dev/null +++ b/arch/x86/platform/pvh/head.S @@ -0,0 +1,177 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * Copyright C 2016, Oracle and/or its affiliates. All rights reserved. + */ + + .code32 + .text +#define _pa(x) ((x) - __START_KERNEL_map) + +#include <linux/elfnote.h> +#include <linux/init.h> +#include <linux/linkage.h> +#include <asm/segment.h> +#include <asm/asm.h> +#include <asm/boot.h> +#include <asm/processor-flags.h> +#include <asm/msr.h> +#include <xen/interface/elfnote.h> + + __HEAD + +/* + * Entry point for PVH guests. + * + * Xen ABI specifies the following register state when we come here: + * + * - `ebx`: contains the physical memory address where the loader has placed + * the boot start info structure. + * - `cr0`: bit 0 (PE) must be set. All the other writeable bits are cleared. + * - `cr4`: all bits are cleared. + * - `cs `: must be a 32-bit read/execute code segment with a base of ‘0’ + * and a limit of ‘0xFFFFFFFF’. The selector value is unspecified. + * - `ds`, `es`: must be a 32-bit read/write data segment with a base of + * ‘0’ and a limit of ‘0xFFFFFFFF’. The selector values are all + * unspecified. + * - `tr`: must be a 32-bit TSS (active) with a base of '0' and a limit + * of '0x67'. + * - `eflags`: bit 17 (VM) must be cleared. Bit 9 (IF) must be cleared. + * Bit 8 (TF) must be cleared. Other bits are all unspecified. + * + * All other processor registers and flag bits are unspecified. The OS is in + * charge of setting up it's own stack, GDT and IDT. + */ + +#define PVH_GDT_ENTRY_CS 1 +#define PVH_GDT_ENTRY_DS 2 +#define PVH_GDT_ENTRY_CANARY 3 +#define PVH_CS_SEL (PVH_GDT_ENTRY_CS * 8) +#define PVH_DS_SEL (PVH_GDT_ENTRY_DS * 8) +#define PVH_CANARY_SEL (PVH_GDT_ENTRY_CANARY * 8) + +ENTRY(pvh_start_xen) + cld + + lgdt (_pa(gdt)) + + mov $PVH_DS_SEL,%eax + mov %eax,%ds + mov %eax,%es + mov %eax,%ss + + /* Stash hvm_start_info. */ + mov $_pa(pvh_start_info), %edi + mov %ebx, %esi + mov _pa(pvh_start_info_sz), %ecx + shr $2,%ecx + rep + movsl + + mov $_pa(early_stack_end), %esp + + /* Enable PAE mode. */ + mov %cr4, %eax + orl $X86_CR4_PAE, %eax + mov %eax, %cr4 + +#ifdef CONFIG_X86_64 + /* Enable Long mode. */ + mov $MSR_EFER, %ecx + rdmsr + btsl $_EFER_LME, %eax + wrmsr + + /* Enable pre-constructed page tables. */ + mov $_pa(init_top_pgt), %eax + mov %eax, %cr3 + mov $(X86_CR0_PG | X86_CR0_PE), %eax + mov %eax, %cr0 + + /* Jump to 64-bit mode. */ + ljmp $PVH_CS_SEL, $_pa(1f) + + /* 64-bit entry point. */ + .code64 +1: + /* Set base address in stack canary descriptor. */ + mov $MSR_GS_BASE,%ecx + mov $_pa(canary), %eax + xor %edx, %edx + wrmsr + + call xen_prepare_pvh + + /* startup_64 expects boot_params in %rsi. */ + mov $_pa(pvh_bootparams), %rsi + mov $_pa(startup_64), %rax + jmp *%rax + +#else /* CONFIG_X86_64 */ + + /* Set base address in stack canary descriptor. */ + movl $_pa(gdt_start),%eax + movl $_pa(canary),%ecx + movw %cx, (PVH_GDT_ENTRY_CANARY * 8) + 2(%eax) + shrl $16, %ecx + movb %cl, (PVH_GDT_ENTRY_CANARY * 8) + 4(%eax) + movb %ch, (PVH_GDT_ENTRY_CANARY * 8) + 7(%eax) + + mov $PVH_CANARY_SEL,%eax + mov %eax,%gs + + call mk_early_pgtbl_32 + + mov $_pa(initial_page_table), %eax + mov %eax, %cr3 + + mov %cr0, %eax + or $(X86_CR0_PG | X86_CR0_PE), %eax + mov %eax, %cr0 + + ljmp $PVH_CS_SEL, $1f +1: + call xen_prepare_pvh + mov $_pa(pvh_bootparams), %esi + + /* startup_32 doesn't expect paging and PAE to be on. */ + ljmp $PVH_CS_SEL, $_pa(2f) +2: + mov %cr0, %eax + and $~X86_CR0_PG, %eax + mov %eax, %cr0 + mov %cr4, %eax + and $~X86_CR4_PAE, %eax + mov %eax, %cr4 + + ljmp $PVH_CS_SEL, $_pa(startup_32) +#endif +END(pvh_start_xen) + + .section ".init.data","aw" + .balign 8 +gdt: + .word gdt_end - gdt_start + .long _pa(gdt_start) + .word 0 +gdt_start: + .quad 0x0000000000000000 /* NULL descriptor */ +#ifdef CONFIG_X86_64 + .quad GDT_ENTRY(0xa09a, 0, 0xfffff) /* PVH_CS_SEL */ +#else + .quad GDT_ENTRY(0xc09a, 0, 0xfffff) /* PVH_CS_SEL */ +#endif + .quad GDT_ENTRY(0xc092, 0, 0xfffff) /* PVH_DS_SEL */ + .quad GDT_ENTRY(0x4090, 0, 0x18) /* PVH_CANARY_SEL */ +gdt_end: + + .balign 16 +canary: + .fill 48, 1, 0 + +early_stack: + .fill BOOT_STACK_SIZE, 1, 0 +early_stack_end: + + ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY, + _ASM_PTR (pvh_start_xen - __START_KERNEL_map)) |