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// Copyright 2017 The Fuchsia Authors
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT
#include <asm.h>
#include <arch/x86/hypervisor/vmx_state.h>
#include <zircon/errors.h>
.text
/* zx_status_t vmx_enter_asm(VmxState* vmx_state) */
FUNCTION(vmx_enter_asm)
// Save callee-saved registers and flags to stack.
push %rbp
push %r15
push %r14
push %r13
push %r12
push %rbx
pushf
// Store the host's stack pointer.
mov %rsp, HS_RSP(%rdi)
// We are going to trample RDI, so move it to RSP.
mov %rdi, %rsp
// Load the guest CR2.
mov GS_CR2(%rsp), %rax
mov %rax, %cr2
// Load the guest registers not covered by the VMCS.
mov GS_RAX(%rsp), %rax
mov GS_RCX(%rsp), %rcx
mov GS_RDX(%rsp), %rdx
mov GS_RBX(%rsp), %rbx
mov GS_RBP(%rsp), %rbp
mov GS_RSI(%rsp), %rsi
mov GS_RDI(%rsp), %rdi
mov GS_R8(%rsp), %r8
mov GS_R9(%rsp), %r9
mov GS_R10(%rsp), %r10
mov GS_R11(%rsp), %r11
mov GS_R12(%rsp), %r12
mov GS_R13(%rsp), %r13
mov GS_R14(%rsp), %r14
mov GS_R15(%rsp), %r15
// If we are resuming, jump to resume.
testb $1, VS_RESUME(%rsp)
jnz .Lresume
// Launch the guest.
//
// Returns to `vmx_guest_exit` on success, or drops through on error.
vmlaunch
jmp .Lfailure
.Lresume:
// Enter the guest.
//
// Returns to `vmx_guest_exit` on success, or drops through on error.
vmresume
.Lfailure:
// If we reach this state, the `vmlaunch` or `vmresume` has failed.
//
// Set the error code (RAX) to ZX_ERR_INTERNAL, and restore the host state.
mov $ZX_ERR_INTERNAL, %rax
jmp .Lrestore_host_regs
// Return to the host after a `vmlaunch` or `vmresume`.
//
// When we return from a VM exit, vmx_state argument is stored in RSP. We
// use this to restore the stack and registers to the state they were in
// when vmx_enter was called.
.align 32
.global vmx_guest_exit
.hidden vmx_guest_exit
vmx_guest_exit:
// Store the guest registers not covered by the VMCS. At this point,
// vmx_state is in RSP.
mov %rax, GS_RAX(%rsp)
mov %rcx, GS_RCX(%rsp)
mov %rdx, GS_RDX(%rsp)
mov %rbx, GS_RBX(%rsp)
mov %rbp, GS_RBP(%rsp)
mov %rsi, GS_RSI(%rsp)
mov %rdi, GS_RDI(%rsp)
mov %r8, GS_R8(%rsp)
mov %r9, GS_R9(%rsp)
mov %r10, GS_R10(%rsp)
mov %r11, GS_R11(%rsp)
mov %r12, GS_R12(%rsp)
mov %r13, GS_R13(%rsp)
mov %r14, GS_R14(%rsp)
mov %r15, GS_R15(%rsp)
// Store the guest CR2.
mov %cr2, %rax
mov %rax, GS_CR2(%rsp)
// Set function result to ZX_OK.
xor %rax, %rax // RAX = ZX_OK
.Lrestore_host_regs:
// Restore the host registers.
//
// At this point, RSP contains vmx_state, and RAX contains the zx_status_t
// error code.
// Load vmx_state from RSP into RDI, and restore our stack.
mov %rsp, %rdi
mov HS_RSP(%rdi), %rsp
// Restore callee-saved registers and flags from stack.
popf
pop %rbx
pop %r12
pop %r13
pop %r14
pop %r15
pop %rbp
ret
END_FUNCTION(vmx_enter_asm)