| Message ID | 20221119003747.2615229-1-seanjc@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: VMX: Access @flags as a 32-bit value in __vmx_vcpu_run() | expand |
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
diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S index 0b5db4de4d09..5bd39f63497d 100644 --- a/arch/x86/kvm/vmx/vmenter.S +++ b/arch/x86/kvm/vmx/vmenter.S @@ -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 /*
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