* [PATCH] KVM: x86: Restore update of required xstate size in guest's CPUID
@ 2020-05-08 23:37 Sean Christopherson
2020-05-09 2:09 ` Xiaoyao Li
2020-05-09 12:51 ` Paolo Bonzini
0 siblings, 2 replies; 3+ messages in thread
From: Sean Christopherson @ 2020-05-08 23:37 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, kvm, linux-kernel, Xiaoyao Li
Restore a guest CPUID update that was unintentional collateral damage
when the per-vCPU guest_xstate_size field was removed.
Cc: Xiaoyao Li <xiaoyao.li@intel.com>
Fixes: d87277414b851 ("kvm: x86: Cleanup vcpu->arch.guest_xstate_size")
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.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) ||
--
2.26.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] KVM: x86: Restore update of required xstate size in guest's CPUID
2020-05-08 23:37 [PATCH] KVM: x86: Restore update of required xstate size in guest's CPUID Sean Christopherson
@ 2020-05-09 2:09 ` Xiaoyao Li
2020-05-09 12:51 ` Paolo Bonzini
1 sibling, 0 replies; 3+ messages in thread
From: Xiaoyao Li @ 2020-05-09 2:09 UTC (permalink / raw)
To: Sean Christopherson, Paolo Bonzini
Cc: Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm,
linux-kernel
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@intel.com>
> Fixes: d87277414b851 ("kvm: x86: Cleanup vcpu->arch.guest_xstate_size")
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.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) ||
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] KVM: x86: Restore update of required xstate size in guest's CPUID
2020-05-08 23:37 [PATCH] KVM: x86: Restore update of required xstate size in guest's CPUID Sean Christopherson
2020-05-09 2:09 ` Xiaoyao Li
@ 2020-05-09 12:51 ` Paolo Bonzini
1 sibling, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2020-05-09 12:51 UTC (permalink / raw)
To: Sean Christopherson
Cc: Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm,
linux-kernel, Xiaoyao Li
On 09/05/20 01:37, Sean Christopherson wrote:
> 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) ||
> -- 2.26.0
Ugh, I'll write a testcase as penance. Squashed, thanks.
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-05-09 12:51 UTC | newest]
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2020-05-08 23:37 [PATCH] KVM: x86: Restore update of required xstate size in guest's CPUID Sean Christopherson
2020-05-09 2:09 ` Xiaoyao Li
2020-05-09 12:51 ` Paolo Bonzini
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