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/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/linkage.h>
#include <asm/asm.h>
#include <asm/bitsperlong.h>
#include <asm/kvm_vcpu_regs.h>
#include <asm/nospec-branch.h>
#define WORD_SIZE (BITS_PER_LONG / 8)
#define VCPU_RAX __VCPU_REGS_RAX * WORD_SIZE
#define VCPU_RCX __VCPU_REGS_RCX * WORD_SIZE
#define VCPU_RDX __VCPU_REGS_RDX * WORD_SIZE
#define VCPU_RBX __VCPU_REGS_RBX * WORD_SIZE
/* Intentionally omit RSP as it's context switched by hardware */
#define VCPU_RBP __VCPU_REGS_RBP * WORD_SIZE
#define VCPU_RSI __VCPU_REGS_RSI * WORD_SIZE
#define VCPU_RDI __VCPU_REGS_RDI * WORD_SIZE
#ifdef CONFIG_X86_64
#define VCPU_R8 __VCPU_REGS_R8 * WORD_SIZE
#define VCPU_R9 __VCPU_REGS_R9 * WORD_SIZE
#define VCPU_R10 __VCPU_REGS_R10 * WORD_SIZE
#define VCPU_R11 __VCPU_REGS_R11 * WORD_SIZE
#define VCPU_R12 __VCPU_REGS_R12 * WORD_SIZE
#define VCPU_R13 __VCPU_REGS_R13 * WORD_SIZE
#define VCPU_R14 __VCPU_REGS_R14 * WORD_SIZE
#define VCPU_R15 __VCPU_REGS_R15 * WORD_SIZE
#endif
.text
/**
* vmx_vmenter - VM-Enter the current loaded VMCS
*
* %RFLAGS.ZF: !VMCS.LAUNCHED, i.e. controls VMLAUNCH vs. VMRESUME
*
* Returns:
* %RFLAGS.CF is set on VM-Fail Invalid
* %RFLAGS.ZF is set on VM-Fail Valid
* %RFLAGS.{CF,ZF} are cleared on VM-Success, i.e. VM-Exit
*
* Note that VMRESUME/VMLAUNCH fall-through and return directly if
* they VM-Fail, whereas a successful VM-Enter + VM-Exit will jump
* to vmx_vmexit.
*/
SYM_FUNC_START(vmx_vmenter)
/* EFLAGS.ZF is set if VMCS.LAUNCHED == 0 */
je 2f
1: vmresume
ret
2: vmlaunch
ret
3: cmpb $0, kvm_rebooting
je 4f
ret
4: ud2
_ASM_EXTABLE(1b, 3b)
_ASM_EXTABLE(2b, 3b)
SYM_FUNC_END(vmx_vmenter)
/**
* vmx_vmexit - Handle a VMX VM-Exit
*
* Returns:
* %RFLAGS.{CF,ZF} are cleared on VM-Success, i.e. VM-Exit
*
* This is vmx_vmenter's partner in crime. On a VM-Exit, control will jump
* here after hardware loads the host's state, i.e. this is the destination
* referred to by VMCS.HOST_RIP.
*/
SYM_FUNC_START(vmx_vmexit)
#ifdef CONFIG_RETPOLINE
ALTERNATIVE "jmp .Lvmexit_skip_rsb", "", X86_FEATURE_RETPOLINE
/* Preserve guest's RAX, it's used to stuff the RSB. */
push %_ASM_AX
/* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */
FILL_RETURN_BUFFER %_ASM_AX, RSB_CLEAR_LOOPS, X86_FEATURE_RETPOLINE
/* Clear RFLAGS.CF and RFLAGS.ZF to preserve VM-Exit, i.e. !VM-Fail. */
or $1, %_ASM_AX
pop %_ASM_AX
.Lvmexit_skip_rsb:
#endif
ret
SYM_FUNC_END(vmx_vmexit)
/**
* __vmx_vcpu_run - Run a vCPU via a transition to VMX guest mode
* @vmx: struct vcpu_vmx * (forwarded to vmx_update_host_rsp)
* @regs: unsigned long * (to guest registers)
* @launched: %true if the VMCS has been launched
*
* Returns:
* 0 on VM-Exit, 1 on VM-Fail
*/
SYM_FUNC_START(__vmx_vcpu_run)
push %_ASM_BP
mov %_ASM_SP, %_ASM_BP
#ifdef CONFIG_X86_64
push %r15
push %r14
push %r13
push %r12
#else
push %edi
push %esi
#endif
push %_ASM_BX
/*
* Save @regs, _ASM_ARG2 may be modified by vmx_update_host_rsp() and
* @regs is needed after VM-Exit to save the guest's register values.
*/
push %_ASM_ARG2
/* Copy @launched to BL, _ASM_ARG3 is volatile. */
mov %_ASM_ARG3B, %bl
/* Adjust RSP to account for the CALL to vmx_vmenter(). */
lea -WORD_SIZE(%_ASM_SP), %_ASM_ARG2
call vmx_update_host_rsp
/* Load @regs to RAX. */
mov (%_ASM_SP), %_ASM_AX
/* Check if vmlaunch or vmresume is needed */
cmpb $0, %bl
/* Load guest registers. Don't clobber flags. */
mov VCPU_RCX(%_ASM_AX), %_ASM_CX
mov VCPU_RDX(%_ASM_AX), %_ASM_DX
mov VCPU_RBX(%_ASM_AX), %_ASM_BX
mov VCPU_RBP(%_ASM_AX), %_ASM_BP
mov VCPU_RSI(%_ASM_AX), %_ASM_SI
mov VCPU_RDI(%_ASM_AX), %_ASM_DI
#ifdef CONFIG_X86_64
mov VCPU_R8 (%_ASM_AX), %r8
mov VCPU_R9 (%_ASM_AX), %r9
mov VCPU_R10(%_ASM_AX), %r10
mov VCPU_R11(%_ASM_AX), %r11
mov VCPU_R12(%_ASM_AX), %r12
mov VCPU_R13(%_ASM_AX), %r13
mov VCPU_R14(%_ASM_AX), %r14
mov VCPU_R15(%_ASM_AX), %r15
#endif
/* Load guest RAX. This kills the @regs pointer! */
mov VCPU_RAX(%_ASM_AX), %_ASM_AX
/* Enter guest mode */
call vmx_vmenter
/* Jump on VM-Fail. */
jbe 2f
/* Temporarily save guest's RAX. */
push %_ASM_AX
/* Reload @regs to RAX. */
mov WORD_SIZE(%_ASM_SP), %_ASM_AX
/* Save all guest registers, including RAX from the stack */
__ASM_SIZE(pop) VCPU_RAX(%_ASM_AX)
mov %_ASM_CX, VCPU_RCX(%_ASM_AX)
mov %_ASM_DX, VCPU_RDX(%_ASM_AX)
mov %_ASM_BX, VCPU_RBX(%_ASM_AX)
mov %_ASM_BP, VCPU_RBP(%_ASM_AX)
mov %_ASM_SI, VCPU_RSI(%_ASM_AX)
mov %_ASM_DI, VCPU_RDI(%_ASM_AX)
#ifdef CONFIG_X86_64
mov %r8, VCPU_R8 (%_ASM_AX)
mov %r9, VCPU_R9 (%_ASM_AX)
mov %r10, VCPU_R10(%_ASM_AX)
mov %r11, VCPU_R11(%_ASM_AX)
mov %r12, VCPU_R12(%_ASM_AX)
mov %r13, VCPU_R13(%_ASM_AX)
mov %r14, VCPU_R14(%_ASM_AX)
mov %r15, VCPU_R15(%_ASM_AX)
#endif
/* Clear RAX to indicate VM-Exit (as opposed to VM-Fail). */
xor %eax, %eax
/*
* Clear all general purpose registers except RSP and RAX to prevent
* speculative use of the guest's values, even those that are reloaded
* via the stack. In theory, an L1 cache miss when restoring registers
* could lead to speculative execution with the guest's values.
* Zeroing XORs are dirt cheap, i.e. the extra paranoia is essentially
* free. RSP and RAX are exempt as RSP is restored by hardware during
* VM-Exit and RAX is explicitly loaded with 0 or 1 to return VM-Fail.
*/
1: xor %ecx, %ecx
xor %edx, %edx
xor %ebx, %ebx
xor %ebp, %ebp
xor %esi, %esi
xor %edi, %edi
#ifdef CONFIG_X86_64
xor %r8d, %r8d
xor %r9d, %r9d
xor %r10d, %r10d
xor %r11d, %r11d
xor %r12d, %r12d
xor %r13d, %r13d
xor %r14d, %r14d
xor %r15d, %r15d
#endif
/* "POP" @regs. */
add $WORD_SIZE, %_ASM_SP
pop %_ASM_BX
#ifdef CONFIG_X86_64
pop %r12
pop %r13
pop %r14
pop %r15
#else
pop %esi
pop %edi
#endif
pop %_ASM_BP
ret
/* VM-Fail. Out-of-line to avoid a taken Jcc after VM-Exit. */
2: mov $1, %eax
jmp 1b
SYM_FUNC_END(__vmx_vcpu_run)
/**
* vmread_error_trampoline - Trampoline from inline asm to vmread_error()
* @field: VMCS field encoding that failed
* @fault: %true if the VMREAD faulted, %false if it failed
* Save and restore volatile registers across a call to vmread_error(). Note,
* all parameters are passed on the stack.
*/
SYM_FUNC_START(vmread_error_trampoline)
push %_ASM_BP
mov %_ASM_SP, %_ASM_BP
push %_ASM_AX
push %_ASM_CX
push %_ASM_DX
#ifdef CONFIG_X86_64
push %rdi
push %rsi
push %r8
push %r9
push %r10
push %r11
#endif
#ifdef CONFIG_X86_64
/* Load @field and @fault to arg1 and arg2 respectively. */
mov 3*WORD_SIZE(%rbp), %_ASM_ARG2
mov 2*WORD_SIZE(%rbp), %_ASM_ARG1
#else
/* Parameters are passed on the stack for 32-bit (see asmlinkage). */
push 3*WORD_SIZE(%ebp)
push 2*WORD_SIZE(%ebp)
#endif
call vmread_error
#ifndef CONFIG_X86_64
add $8, %esp
#endif
/* Zero out @fault, which will be popped into the result register. */
_ASM_MOV $0, 3*WORD_SIZE(%_ASM_BP)
#ifdef CONFIG_X86_64
pop %r11
pop %r10
pop %r9
pop %r8
pop %rsi
pop %rdi
#endif
pop %_ASM_DX
pop %_ASM_CX
pop %_ASM_AX
pop %_ASM_BP
ret
SYM_FUNC_END(vmread_error_trampoline)
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