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AKwUvByfsog4nkQfHoJRA1lBo8Ej1fM9jHzwxEZA7qomUfH1xQrcsOnRD8K61FjoG3HCOevoPeJVXLqyLCNc@lists.linux.dev X-Gm-Message-State: AFuF++mr81rZCLGKJrYL/I1MkYQCl52fzMMIGX7CcoivaaX3Y3uKtfp5 0mPjtvn0plk1P39W9lSdy3tUQlYR0L7seqYgcSfBHcF5rzVsJrZr6BwgwR97mjZmHmxwm2FxSF7 o3xBkZQ== X-Received: from pjro5.prod.google.com ([2002:a17:90a:b885:b0:3a0:645b:1c57]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90a:d888:b0:39e:4c7f:8b16 with SMTP id 98e67ed59e1d1-39e54cf8bdbmr17922638a91.27.1790012695572; Mon, 21 Sep 2026 10:44:55 -0700 (PDT) Reply-To: Sean Christopherson Date: Mon, 21 Sep 2026 10:44:45 -0700 In-Reply-To: <20260921174445.911676-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260921174445.911676-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog Message-ID: <20260921174445.911676-8-seanjc@google.com> Subject: [PATCH v2 7/7] KVM: WARN if vCPU creation is in-progress when locking all vCPUs From: Sean Christopherson To: Madhavan Srinivasan , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Sean Christopherson , Paolo Bonzini , Kiryl Shutsemau , Rick Edgecombe Cc: Nicholas Piggin , Atish Patra , Alexandre Ghiti , Dave Hansen , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, x86@kernel.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, Jean-Christophe Guillain , "=?UTF-8?q?Pawe=C5=82=20S?=" Content-Type: text/plain; charset="UTF-8" Now that KVM holds kvm->lock for the entirety of vCPU creation, from when created_vcpus is incremented until the new vCPU is fully onlined, WARN if the impossible happens and KVM somehow sees a discrepancy between the number of vCPUs "created" and "onlined". Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 985af39b980a..e66d9761ee49 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1363,7 +1363,7 @@ int kvm_trylock_all_vcpus(struct kvm *kvm) lockdep_assert_held(&kvm->lock); - if (kvm_is_vcpu_creation_in_progress(kvm)) + if (WARN_ON_ONCE(kvm_is_vcpu_creation_in_progress(kvm))) return -EBUSY; kvm_for_each_vcpu(i, vcpu, kvm) @@ -1389,7 +1389,7 @@ int kvm_lock_all_vcpus(struct kvm *kvm) lockdep_assert_held(&kvm->lock); - if (kvm_is_vcpu_creation_in_progress(kvm)) + if (WARN_ON_ONCE(kvm_is_vcpu_creation_in_progress(kvm))) return -EBUSY; kvm_for_each_vcpu(i, vcpu, kvm) { -- 2.55.0.1082.g2b9226bbc0-goog