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KVM: VMX: Return VM-Fail from vCPU-run assembly via standard ABI reg 

...to prepare for making the assembly sub-routine callable from C code.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2019-01-25 07:41:17 -08:00 committed by Paolo Bonzini
parent 77df549559
commit e75c3c3a04
2 changed files with 12 additions and 12 deletions
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16
arch/x86/kvm/vmx/vmenter.S
View File

@ -87,7 +87,7 @@ ENDPROC(vmx_vmexit)
* @launched: %true if the VMCS has been launched
*
* Returns:
* %RBX is 0 on VM-Exit, 1 on VM-Fail
* 0 on VM-Exit, 1 on VM-Fail
*/
ENTRY(__vmx_vcpu_run)
push %_ASM_BP
@ -163,17 +163,17 @@ ENTRY(__vmx_vcpu_run)
mov %r15, VCPU_R15(%_ASM_AX)
#endif
/* Clear EBX to indicate VM-Exit (as opposed to VM-Fail). */
xor %ebx, %ebx
/* Clear RAX to indicate VM-Exit (as opposed to VM-Fail). */
xor %eax, %eax
/*
* Clear all general purpose registers except RSP and RBX to prevent
* 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 RBX are exempt as RSP is restored by hardware during
* VM-Exit and RBX is explicitly loaded with 0 or 1 to "return" VM-Fail.
* 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:
#ifdef CONFIG_X86_64
@ -186,7 +186,7 @@ ENTRY(__vmx_vcpu_run)
xor %r14d, %r14d
xor %r15d, %r15d
#endif
xor %eax, %eax
xor %ebx, %ebx
xor %ecx, %ecx
xor %edx, %edx
xor %esi, %esi
@ -199,6 +199,6 @@ ENTRY(__vmx_vcpu_run)
ret
/* VM-Fail. Out-of-line to avoid a taken Jcc after VM-Exit. */
2: mov $1, %ebx
2: mov $1, %eax
jmp 1b
ENDPROC(__vmx_vcpu_run)

8
arch/x86/kvm/vmx/vmx.c
View File

@ -6446,20 +6446,20 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
asm(
"call __vmx_vcpu_run \n\t"
: ASM_CALL_CONSTRAINT, "=b"(vmx->fail),
: ASM_CALL_CONSTRAINT, "=a"(vmx->fail),
#ifdef CONFIG_X86_64
"=D"((int){0}), "=S"((int){0}), "=d"((int){0})
: "D"(vmx), "S"(&vcpu->arch.regs), "d"(vmx->loaded_vmcs->launched)
#else
"=a"((int){0}), "=d"((int){0}), "=c"((int){0})
"=d"((int){0}), "=c"((int){0})
: "a"(vmx), "d"(&vcpu->arch.regs), "c"(vmx->loaded_vmcs->launched)
#endif
: "cc", "memory"
#ifdef CONFIG_X86_64
, "rax", "rcx"
, "rbx", "rcx"
, "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"
#else
, "edi", "esi"
, "ebx", "edi", "esi"
#endif
);