Messages in this thread Patch in this message | | | From | Paolo Bonzini <> | Subject | [PATCH] KVM: x86: avoid unnecessary XSETBV on guest entry | Date | Wed, 13 Dec 2017 13:51:52 +0100 |
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xsetbv can be expensive when running on nested virtualization, try to avoid it.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/kvm/x86.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 0f82e2cbf64c..daa1918031df 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -702,7 +702,8 @@ static void kvm_load_guest_xcr0(struct kvm_vcpu *vcpu) if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) && !vcpu->guest_xcr0_loaded) { /* kvm_set_xcr() also depends on this */ - xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0); + if (vcpu->arch.xcr0 != host_xcr0) + xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0); vcpu->guest_xcr0_loaded = 1; } } -- 1.8.3.1
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