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Mon, 05 Jan 2026 12:23:01 -0800 (PST) Date: Mon, 5 Jan 2026 12:23:00 -0800 In-Reply-To: <20251231151153.3146021-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <2025122926-gigabyte-rectangle-0c68@gregkh> <20251231151153.3146021-1-sashal@kernel.org> Message-ID: Subject: Re: [PATCH 6.1.y] KVM: nVMX: Immediately refresh APICv controls as needed on nested VM-Exit From: Sean Christopherson To: Sasha Levin Cc: stable@vger.kernel.org, Dongli Zhang , Chao Gao Content-Type: text/plain; charset="us-ascii" On Wed, Dec 31, 2025, Sasha Levin wrote: > From: Dongli Zhang > > [ Upstream commit 29763138830916f46daaa50e83e7f4f907a3236b ] > > If an APICv status updated was pended while L2 was active, immediately > refresh vmcs01's controls instead of pending KVM_REQ_APICV_UPDATE as > kvm_vcpu_update_apicv() only calls into vendor code if a change is > necessary. > > E.g. if APICv is inhibited, and then activated while L2 is running: > > kvm_vcpu_update_apicv() > | > -> __kvm_vcpu_update_apicv() > | > -> apic->apicv_active = true > | > -> vmx_refresh_apicv_exec_ctrl() > | > -> vmx->nested.update_vmcs01_apicv_status = true > | > -> return > > Then L2 exits to L1: > > __nested_vmx_vmexit() > | > -> kvm_make_request(KVM_REQ_APICV_UPDATE) > > vcpu_enter_guest(): KVM_REQ_APICV_UPDATE > -> kvm_vcpu_update_apicv() > | > -> __kvm_vcpu_update_apicv() > | > -> return // because if (apic->apicv_active == activate) > > Reported-by: Chao Gao > Closes: https://lore.kernel.org/all/aQ2jmnN8wUYVEawF@intel.com > Fixes: 7c69661e225c ("KVM: nVMX: Defer APICv updates while L2 is active until L1 is active") > Cc: stable@vger.kernel.org > Signed-off-by: Dongli Zhang > [sean: write changelog] > Link: https://patch.msgid.link/20251205231913.441872-3-seanjc@google.com > Signed-off-by: Sean Christopherson > [ exported vmx_refresh_apicv_exec_ctrl() and added declaration in vmx.h ] > Signed-off-by: Sasha Levin > --- Acked-by: Sean Christopherson