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Thu, 04 Jul 2024 18:17:37 -0700 (PDT) X-Google-Smtp-Source: AGHT+IE9n2tSZ8Hrz4jp8hEVRmgj4S+DhW2AV216ObXnCIpoWjvDsNTMJ4pjCYePPvQxIXv+Rhm/RA== X-Received: by 2002:a05:620a:5343:b0:797:a485:28ef with SMTP id af79cd13be357-79eee193311mr293928785a.8.1720142257695; Thu, 04 Jul 2024 18:17:37 -0700 (PDT) Received: from starship ([2607:fea8:fc01:7b7f:6adb:55ff:feaa:b156]) by smtp.gmail.com with ESMTPSA id af79cd13be357-79d692f05dcsm730170385a.92.2024.07.04.18.17.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Jul 2024 18:17:37 -0700 (PDT) Message-ID: <8fb52f51eb1ff52f5fe666806205cb77a98b6195.camel@redhat.com> Subject: Re: [PATCH v2 15/49] KVM: x86: Zero out PV features cache when the CPUID leaf is not present From: Maxim Levitsky To: Sean Christopherson , Paolo Bonzini , Vitaly Kuznetsov Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Hou Wenlong , Kechen Lu , Oliver Upton , Binbin Wu , Yang Weijiang , Robert Hoo Date: Thu, 04 Jul 2024 21:17:36 -0400 In-Reply-To: <20240517173926.965351-16-seanjc@google.com> References: <20240517173926.965351-1-seanjc@google.com> <20240517173926.965351-16-seanjc@google.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7bit 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 > Signed-off-by: Sean Christopherson > --- > 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 Best regards, Maxim Levitsky