diff mbox series

[v2,15/49] KVM: x86: Zero out PV features cache when the CPUID leaf is not present

Message ID 20240517173926.965351-16-seanjc@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: x86: CPUID overhaul, fixes, and caching | expand

Commit Message

Sean Christopherson May 17, 2024, 5:38 p.m. UTC 
Clear KVM's PV feature cache prior when processing a new guest CPUID so
that KVM doesn't keep a stale cache entry if userspace does KVM_SET_CPUID2
multiple times, once with a PV features entry, and a second time without.

Fixes: 66570e966dd9 ("kvm: x86: only provide PV features if enabled in guest's CPUID")
Cc: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/cpuid.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Maxim Levitsky July 5, 2024, 1:17 a.m. UTC | #1 
On Fri, 2024-05-17 at 10:38 -0700, Sean Christopherson wrote:
> Clear KVM's PV feature cache prior when processing a new guest CPUID so
> that KVM doesn't keep a stale cache entry if userspace does KVM_SET_CPUID2
> multiple times, once with a PV features entry, and a second time without.
> 
> Fixes: 66570e966dd9 ("kvm: x86: only provide PV features if enabled in guest's CPUID")
> Cc: Oliver Upton <oliver.upton@linux.dev>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  arch/x86/kvm/cpuid.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index f756a91a3f2f..be1c8f43e090 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -246,6 +246,8 @@ void kvm_update_pv_runtime(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm_cpuid_entry2 *best = kvm_find_kvm_cpuid_features(vcpu);
>  
> +	vcpu->arch.pv_cpuid.features = 0;
> +
>  	/*
>  	 * save the feature bitmap to avoid cpuid lookup for every PV
>  	 * operation

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>

Best regards,
	Maxim Levitsky
diff mbox series

Patch

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index f756a91a3f2f..be1c8f43e090 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -246,6 +246,8 @@  void kvm_update_pv_runtime(struct kvm_vcpu *vcpu)
 {
 	struct kvm_cpuid_entry2 *best = kvm_find_kvm_cpuid_features(vcpu);
 
+	vcpu->arch.pv_cpuid.features = 0;
+
 	/*
 	 * save the feature bitmap to avoid cpuid lookup for every PV
 	 * operation