KVM: x86: avoid unnecessary XSETBV on guest entry
"Linux Kernel Mailing List" <[email protected]> Sat, 10 Feb 2018 22:00:19 +0000 (UTC)
| Newsgroups | gmane.linux.kernel.commits.head |
|---|---|
| Message-ID | <[email protected]> |
Web: https://git.kernel.org/torvalds/c/476b7adaa3272557168b287175b1e9e943913404 Commit: 476b7adaa3272557168b287175b1e9e943913404 Parent: efdab992813fb2ed825745625b83c05032e9cda2 Refname: refs/heads/master Author: Paolo Bonzini <[email protected]> AuthorDate: Wed Dec 13 13:51:32 2017 +0100 Committer: Radim Krčmář <[email protected]> CommitDate: Tue Jan 16 16:34:13 2018 +0100 KVM: x86: avoid unnecessary XSETBV on guest entry xsetbv can be expensive when running on nested virtualization, try to avoid it. Reviewed-by: Jim Mattson <[email protected]> Reviewed-by: Wanpeng Li <[email protected]> Reviewed-by: Quan Xu <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]> Signed-off-by: Radim Krčmář <[email protected]> --- 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 a3dd44bb6f1e..56d8a1e11e50 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; } } -- To unsubscribe from this list: send the line "unsubscribe git-commits-head" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html