On Wed, May 12, 2021, Paolo Bonzini wrote: > On 12/05/21 13:21, Uros Bizjak wrote: > > There is no need to use %__ASM_AX within CONFIG_X86_64. The macro > > will always expand to %rax. > > diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S > > index 3a6461694fc2..9273709e4800 100644 > > --- a/arch/x86/kvm/vmx/vmenter.S > > +++ b/arch/x86/kvm/vmx/vmenter.S > > @@ -142,14 +142,14 @@ SYM_FUNC_START(__vmx_vcpu_run) > > 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 > > + mov VCPU_R8 (%rax), %r8 > > + mov VCPU_R9 (%rax), %r9 > > + mov VCPU_R10(%rax), %r10 > > + mov VCPU_R11(%rax), %r11 > > + mov VCPU_R12(%rax), %r12 > > + mov VCPU_R13(%rax), %r13 > > + mov VCPU_R14(%rax), %r14 > > + mov VCPU_R15(%rax), %r15 > > #endif > > /* Load guest RAX. This kills the @regs pointer! */ > > mov VCPU_RAX(%_ASM_AX), %_ASM_AX > > @@ -175,14 +175,14 @@ SYM_FUNC_START(__vmx_vcpu_run) > > 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) > > + mov %r8, VCPU_R8 (%rax) > > + mov %r9, VCPU_R9 (%rax) > > + mov %r10, VCPU_R10(%rax) > > + mov %r11, VCPU_R11(%rax) > > + mov %r12, VCPU_R12(%rax) > > + mov %r13, VCPU_R13(%rax) > > + mov %r14, VCPU_R14(%rax) > > + mov %r15, VCPU_R15(%rax) > > #endif > > /* Clear RAX to indicate VM-Exit (as opposed to VM-Fail). */ > > > > It looks a bit weird either way (either the address is different within the > #ifdef, or the address is different from the destinatino), so I lean more > towards avoiding churn. Even though it's unnecessary, I prefer %_ASM_AX since it provides a consistent flow across the 64-bit-only boundary.
