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([2a00:23c7:df82:3001:20f1:15b5:79c7:cb20]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38c2a188673sm8281574f8f.46.2025.01.26.08.15.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 26 Jan 2025 08:15:51 -0800 (PST) Message-ID: Date: Sun, 26 Jan 2025 16:15:50 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: paul@xen.org Subject: Re: [PATCH v2] KVM: x86: Update Xen TSC leaves during CPUID emulation To: Fred Griffoul , kvm@vger.kernel.org Cc: griffoul@gmail.com, vkuznets@redhat.com, Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , David Woodhouse , Paul Durrant , linux-kernel@vger.kernel.org References: <20250124150539.69975-1-fgriffo@amazon.co.uk> Content-Language: en-US From: "Durrant, Paul" In-Reply-To: <20250124150539.69975-1-fgriffo@amazon.co.uk> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 24/01/2025 15:05, Fred Griffoul wrote: > The Xen emulation in KVM modifies certain CPUID leaves to expose > TSC information to the guest. > > Previously, these CPUID leaves were updated whenever guest time changed, > but this conflicts with KVM_SET_CPUID/KVM_SET_CPUID2 ioctls which reject > changes to CPUID entries on running vCPUs. > > Fix this by updating the TSC information directly in the CPUID emulation > handler instead of modifying the vCPU's CPUID entries. > > Signed-off-by: Sean Christopherson > Signed-off-by: Fred Griffoul > --- > arch/x86/kvm/cpuid.c | 16 ++++++++++++++++ > arch/x86/kvm/x86.c | 3 +-- > arch/x86/kvm/x86.h | 1 + > arch/x86/kvm/xen.c | 23 ----------------------- > arch/x86/kvm/xen.h | 13 +++++++++++-- > 5 files changed, 29 insertions(+), 27 deletions(-) > Reviewed-by: Paul Durrant