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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 On 4/8/26 20:22, Paolo Bonzini wrote: > Reuse the same assembly as SVM, just with alternatives instead > of cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS). > > Due to the dearth of registers in 32-bit x86, save/restore %eax > across the restoring sequence, keeping it simple; the main alternative > would be to leave vmx and flags on the stack, avoiding the need to read > flags from %ebx. It's not really measurable difference. > > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/vmenter.h | 4 ++-- > arch/x86/kvm/vmx/vmenter.S | 25 +++++++++++++++---------- > arch/x86/kvm/vmx/vmx.c | 25 ------------------------- > arch/x86/kvm/vmx/vmx.h | 1 - > 4 files changed, 17 insertions(+), 38 deletions(-) > > diff --git a/arch/x86/kvm/vmenter.h b/arch/x86/kvm/vmenter.h > index e746e1328d3f..d822dafc75f7 100644 > --- a/arch/x86/kvm/vmenter.h > +++ b/arch/x86/kvm/vmenter.h > @@ -55,7 +55,7 @@ > #ifdef CONFIG_X86_64 > mov PER_CPU_VAR(x86_spec_ctrl_current), %rdx > cmp \guest_spec_ctrl, %rdx > - je \label > + ALTERNATIVE "", __stringify(je \label), X86_FEATURE_KERNEL_IBRS Actually the other way round: ALTERNATIVE __stringify(je \label), "", X86_FEATURE_KERNEL_IBRS > movl %edx, %eax > shr $32, %rdx > #else > @@ -66,7 +66,7 @@ > mov 4 + \guest_spec_ctrl, %edi > xor %edx, %edi > or %edi, %esi > - je \label > + ALTERNATIVE "", __stringify(je \label), X86_FEATURE_KERNEL_IBRS Same here. Paolo