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AJvYcCWYLzh0kyWzyreiMGd/l1UtunAKwQIkBl0zhSrIuaRosT5N8nW4dkpgCcSf4jtGx0EhkSGIhGjVGqpdgjD7Rn0C@lists.infradead.org X-Gm-Message-State: AOJu0YyxWqdh10lyOKCT/ok1vInsxW4UAp7h4uhSqOe/AWPzCQ17/8ZU MBtJegkhgy99xQwBKyGbs8hn9Aobc59cZSu+vaXa4JA+xQU1n5eR3zXOWONLiyundhIm9HaE8wL Zpw== X-Google-Smtp-Source: AGHT+IHcYPdS+ntkX0QFkx6mSIlTj1AO51n1TbjklGmZnx1XnyN+enbKGYXER1TOaq4aVQk11+wCSyWBHf8= X-Received: from pjbsw3.prod.google.com ([2002:a17:90b:2c83:b0:2f9:c349:2f84]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:2dcc:b0:2fa:157e:c790 with SMTP id 98e67ed59e1d1-3056ee181a6mr177513a91.5.1743540413076; Tue, 01 Apr 2025 13:46:53 -0700 (PDT) Date: Tue, 1 Apr 2025 13:44:15 -0700 In-Reply-To: <20250401204425.904001-1-seanjc@google.com> Mime-Version: 1.0 References: <20250401204425.904001-1-seanjc@google.com> X-Mailer: git-send-email 2.49.0.504.g3bcea36a83-goog Message-ID: <20250401204425.904001-4-seanjc@google.com> Subject: [PATCH 03/12] KVM: Initialize irqfd waitqueue callback when adding to the queue From: Sean Christopherson To: Paolo Bonzini , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Marc Zyngier , Oliver Upton , Sean Christopherson , Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-riscv@lists.infradead.org, David Matlack , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250401_134654_308952_9E5AF5E5 X-CRM114-Status: GOOD ( 16.15 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Sean Christopherson Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Initialize the irqfd waitqueue callback immediately prior to inserting the irqfd into the eventfd's waitqueue. Pre-initializing the state in a completely different context is all kinds of confusing, and incorrectly suggests that the waitqueue function needs to be initialize prior to vfs_poll(). Signed-off-by: Sean Christopherson --- virt/kvm/eventfd.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index e47b7b6df94f..69bf2881635e 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -256,6 +256,13 @@ static void kvm_irqfd_register(struct file *file, wait_queue_head_t *wqh, struct kvm_irqfd_pt *p = container_of(pt, struct kvm_irqfd_pt, pt); struct kvm_kernel_irqfd *irqfd = p->irqfd; + /* + * Add the irqfd as a priority waiter on the eventfd, with a custom + * wake-up handler, so that KVM *and only KVM* is notified whenever the + * underlying eventfd is signaled. + */ + init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup); + add_wait_queue_priority(wqh, &irqfd->wait); } @@ -395,12 +402,6 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args) mutex_unlock(&kvm->irqfds.resampler_lock); } - /* - * Install our own custom wake-up handling so we are notified via - * a callback whenever someone signals the underlying eventfd - */ - init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup); - /* * Set the irqfd routing and add it to KVM's list before registering * the irqfd with the eventfd, so that the routing information is valid