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Wed, 2 Apr 2025 02:18:59 +0000 Date: Wed, 2 Apr 2025 10:17:21 +0800 From: Yan Zhao To: Sean Christopherson CC: Paolo Bonzini , , Subject: Re: [PATCH 1/2] KVM: VMX: Assert that IRQs are disabled when putting vCPU on PI wakeup list Message-ID: Reply-To: Yan Zhao References: <20250401154727.835231-1-seanjc@google.com> <20250401154727.835231-2-seanjc@google.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20250401154727.835231-2-seanjc@google.com> X-ClientProxiedBy: SI2PR02CA0013.apcprd02.prod.outlook.com (2603:1096:4:194::21) To DS7PR11MB5966.namprd11.prod.outlook.com (2603:10b6:8:71::6) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR11MB5966:EE_|PH0PR11MB7421:EE_ X-MS-Office365-Filtering-Correlation-Id: f437fa10-0a3b-4851-4b94-08dd718cba5b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|376014|7053199007; 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KVM relies on > IRQs being disabled until the vCPU task is fully scheduled out, i.e. until > the scheduler has dropped all of its per-CPU locks (e.g. for the runqueue), > as attempting to wake the task while it's being scheduled out could lead > to deadlock. > > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/vmx/posted_intr.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c > index ec08fa3caf43..840d435229a8 100644 > --- a/arch/x86/kvm/vmx/posted_intr.c > +++ b/arch/x86/kvm/vmx/posted_intr.c > @@ -148,9 +148,8 @@ static void pi_enable_wakeup_handler(struct kvm_vcpu *vcpu) > struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu); > struct vcpu_vmx *vmx = to_vmx(vcpu); > struct pi_desc old, new; > - unsigned long flags; > > - local_irq_save(flags); > + lockdep_assert_irqs_disabled(); > > raw_spin_lock(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu)); > list_add_tail(&vmx->pi_wakeup_list, > @@ -176,8 +175,6 @@ static void pi_enable_wakeup_handler(struct kvm_vcpu *vcpu) > */ > if (pi_test_on(&new)) > __apic_send_IPI_self(POSTED_INTR_WAKEUP_VECTOR); > - > - local_irq_restore(flags); > } > > static bool vmx_needs_pi_wakeup(struct kvm_vcpu *vcpu) > -- > 2.49.0.472.ge94155a9ec-goog >