KVM: VMX: Access @flags as a 32-bit value in __vmx_vcpu_run()
Commit Message
Access @flags using 32-bit operands when saving and testing @flags for
VMX_RUN_VMRESUME, as using 8-bit operands is unnecessarily fragile due
to relying on VMX_RUN_VMRESUME being in bits 0-7. The behavior of
treating @flags a single byte is a holdover from when the param was
"bool launched", i.e. is not deliberate.
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/vmx/vmenter.S | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
base-commit: d663b8a285986072428a6a145e5994bc275df994
Comments
On Fri, Nov 18, 2022 at 5:33 PM Sean Christopherson <seanjc@google.com> wrote:
>
> Access @flags using 32-bit operands when saving and testing @flags for
> VMX_RUN_VMRESUME, as using 8-bit operands is unnecessarily fragile due
> to relying on VMX_RUN_VMRESUME being in bits 0-7. The behavior of
> treating @flags a single byte is a holdover from when the param was
> "bool launched", i.e. is not deliberate.
>
> Cc: Alexey Dobriyan <adobriyan@gmail.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
On Sat, 19 Nov 2022 00:37:47 +0000, Sean Christopherson wrote:
> Access @flags using 32-bit operands when saving and testing @flags for
> VMX_RUN_VMRESUME, as using 8-bit operands is unnecessarily fragile due
> to relying on VMX_RUN_VMRESUME being in bits 0-7. The behavior of
> treating @flags a single byte is a holdover from when the param was
> "bool launched", i.e. is not deliberate.
>
>
> [...]
Applied to kvm-x86 vmx, thanks!
[1/1] KVM: VMX: Access @flags as a 32-bit value in __vmx_vcpu_run()
https://github.com/kvm-x86/linux/commit/55de8353fc67
--
https://github.com/kvm-x86/linux/tree/next
https://github.com/kvm-x86/linux/tree/fixes
@@ -69,8 +69,8 @@ SYM_FUNC_START(__vmx_vcpu_run)
*/
push %_ASM_ARG2
- /* Copy @flags to BL, _ASM_ARG3 is volatile. */
- mov %_ASM_ARG3B, %bl
+ /* Copy @flags to EBX, _ASM_ARG3 is volatile. */
+ mov %_ASM_ARG3L, %ebx
lea (%_ASM_SP), %_ASM_ARG2
call vmx_update_host_rsp
@@ -106,7 +106,7 @@ SYM_FUNC_START(__vmx_vcpu_run)
mov (%_ASM_SP), %_ASM_AX
/* Check if vmlaunch or vmresume is needed */
- testb $VMX_RUN_VMRESUME, %bl
+ test $VMX_RUN_VMRESUME, %ebx
/* Load guest registers. Don't clobber flags. */
mov VCPU_RCX(%_ASM_AX), %_ASM_CX
@@ -128,7 +128,7 @@ SYM_FUNC_START(__vmx_vcpu_run)
/* Load guest RAX. This kills the @regs pointer! */
mov VCPU_RAX(%_ASM_AX), %_ASM_AX
- /* Check EFLAGS.ZF from 'testb' above */
+ /* Check EFLAGS.ZF from 'test VMX_RUN_VMRESUME' above */
jz .Lvmlaunch
/*