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Sun, 15 Nov 2026 00:10:31 -0800 (PST) X-Received: by 2002:a05:6000:25c6:b0:48c:77ad:d52d with SMTP id ffacd0b85a97d-49c73165309mr15480342f8f.43.1794730230626; Sun, 15 Nov 2026 00:10:30 -0800 (PST) Received: from sgarzare-redhat ([193.207.75.235]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-49c609c602dsm14853290f8f.46.2026.11.15.00.10.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Nov 2026 00:10:28 -0800 (PST) Date: Sun, 15 Nov 2026 09:10:14 +0100 From: Stefano Garzarella To: Sean Christopherson Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Carlos =?utf-8?B?TMOzcGV6?= , Chris Oo Subject: Re: [PATCH] KVM: SVM: Sync CR8 to the local APIC after marking the VMCB clean Message-ID: References: <20261113162556.461390-1-seanjc@google.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20261113162556.461390-1-seanjc@google.com> On Fri, Nov 13, 2026 at 08:25:56AM -0800, Sean Christopherson wrote: >From: Chris Oo > >Sync CR8 from the VMCB to the TPR *after* marking all VMCB fields as clean, >as syncing CR8 can toggle the CR8 write intercept and thus mark INTERCEPTS >as dirty. Clobbering the dirty bit can result in KVM failing to detect CR8 >writes if the underlying "hardware" uses the clean bits to optimize VMRUN, >e.g. when KVM is running on Hyper-V. > >Failure to intercept CR8 usually manifests as hangs when running Windows as >L2, as KVM's view of vTPR stays high and so KVM never injects pending IRQs. > >Fixes: bb365a506b1e ("KVM: x86: Unconditionally recompute CR8 intercept on PPR update") >Cc: stable@vger.kernel.org >Cc: Carlos López >Cc: Stefano Garzarella >Not-signed-off-by: Chris Oo >[sean: rewrite changelog, massage comment] >Signed-off-by: Sean Christopherson >--- LGTM! Acked-by: Stefano Garzarella