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Date: Sat, 9 May 2020 10:09:00 +0800 From: Xiaoyao Li <xiaoyao.li@...el.com> To: Sean Christopherson <sean.j.christopherson@...el.com>, Paolo Bonzini <pbonzini@...hat.com> Cc: Vitaly Kuznetsov <vkuznets@...hat.com>, Wanpeng Li <wanpengli@...cent.com>, Jim Mattson <jmattson@...gle.com>, Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] KVM: x86: Restore update of required xstate size in guest's CPUID On 5/9/2020 7:37 AM, Sean Christopherson wrote: > Restore a guest CPUID update that was unintentional collateral damage > when the per-vCPU guest_xstate_size field was removed. It's really unintentional. None of us noticed it. :( It's good that you catch it! > Cc: Xiaoyao Li <xiaoyao.li@...el.com> > Fixes: d87277414b851 ("kvm: x86: Cleanup vcpu->arch.guest_xstate_size") > Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com> > --- > > There's nothing more thrilling than watching bisect home in on your own > commits, only to land on someone else's on the very last step. > > arch/x86/kvm/cpuid.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 35845704cf57a..cd708b0b460a0 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -84,11 +84,13 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) > kvm_read_cr4_bits(vcpu, X86_CR4_PKE)); > > best = kvm_find_cpuid_entry(vcpu, 0xD, 0); > - if (!best) > + if (!best) { > vcpu->arch.guest_supported_xcr0 = 0; > - else > + } else { > vcpu->arch.guest_supported_xcr0 = > (best->eax | ((u64)best->edx << 32)) & supported_xcr0; > + best->ebx = xstate_required_size(vcpu->arch.xcr0, false); > + } > > best = kvm_find_cpuid_entry(vcpu, 0xD, 1); > if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) || >
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