From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f71.google.com (mail-pj1-f71.google.com [209.85.216.71]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A36B449B5CC for ; Mon, 14 Sep 2026 18:12:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.71 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789409558; cv=none; b=q/M8bs6R8pG9KzvkXjyTQUETzUNsqNsM5F8ZAAnYZljHE8Tk6qmzB8Bv4SVXZCgBwl/JiGVpuSMWBNusYul9OK+qNMlxAED23BZiFPXQg2saN9aN2lFMGP95aUlRHXmEW1vsabo6igAgs/HrlDrupOyqj23fqV3BznQIBPRGpCA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789409558; c=relaxed/simple; bh=dJrvpB5i1rMlVAI+qV3aDnzI33qsio45lawj5JfEjHs=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=lRVRavCBtGrKZnL1RpSiX8x4P2O0q+Ea1E2/B7ECJ1U4dOP7EZ0AGpzquu8/mjmK/BwRo6C1O2OcBgSuCWdv6gAeuUxm7JTaYPiqO+YSJrJqgi2sdBBJEqZ7eOvvnpvFZ8tYL9TE3Yu160523v2gMj9cGKCo4e3Fzxh0ZUYDNAg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=ll3QclfO; arc=none smtp.client-ip=209.85.216.71 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ll3QclfO" Received: by mail-pj1-f71.google.com with SMTP id 98e67ed59e1d1-38ecc48b3c2so5761868a91.1 for ; Mon, 14 Sep 2026 11:12:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1789409552; x=1790014352; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:reply-to:from:to:cc:subject:date:message-id :reply-to:content-type; bh=eILuU/ujF/gCxOipJ6aAt7TsmD8PW8XQkQA4cx27AIY=; b=ll3QclfObzQf89D5n0MifPRcHjYAPY8zYA1imWEzyXbIBgBF73qzGNuQny0cTx/z9V gJtZLdKJCLQYt9JykqMC7qt/3HYW0YBl2DYyYSB5JmdukUz026bZpY95atFn75EsV2KF CbUO8svIDspuK4reDoj0cNUd6EncsHvvBFKxKa+eJhyNS5aQ8Zs8wxE0+Uo+w5xiQPDe 0s/KJKd1Ht+XUeR8xo0IZGesiy3P9gRw5G+YnG6p8B5y9JRsap2+XLKJ+jhJ+XoXr9dj q0in9xGGsDXmqEhjP97w9vlPXv0VQJ07dMXk0ai0/pUncWstt1n59I8tYZYyd55WJuXU hUwQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1789409552; x=1790014352; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:reply-to:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to:content-type; bh=eILuU/ujF/gCxOipJ6aAt7TsmD8PW8XQkQA4cx27AIY=; b=J148Tzdyvn9YVSoZyBDeC+5EoIraU74LExGN2KsnfdcEKyZpUV2xbA89fVdK2Mz6Bg h3FLRgb1t/xKf2vJCoKdxI2G05Yi1PuLjd6kQu47t708jqpTVblH58JScLTOYEzyKRu8 lhL6JbaxqbBU4onKSFoi52v52ci0Iite68Y9fBZHxZYJ2KlVH0CqrmI8dH7EXF4roltF 15njVn627E9RDv59togFCYY6iNqxwx2nK63roqRpOlM3hVpJfmI+j4dIkEovAJzpwGzo VNQRK5sXhXe15/zax15+IpsZB7PN3GCNblHI1hHwpYckhxFHYJvxeoxZDLx3PJ3VJ8L0 I6jA== X-Forwarded-Encrypted: i=1; AKwUvBzCWuco+3/FDd8n6Z1J6UUfZrvYHgGQ4VaSo/kHHH5KhaDS5RRYF9cS6F3vxjvE5pcPpA4Qf3HG3R1bOak=@vger.kernel.org X-Gm-Message-State: AFuF++liV9BEsSHp/6To69mVToo3O4EBDwsnBmp+665xrZkZFzqpZpIs +Ugn8bDwUL9mB7E6nFPTH7hIFZkG3DLmpYJniDUZvpz4lMRMCXwNvcSYbhHC9TbpkvG0Z6LBCm7 cSmH85g== X-Received: from pjso8.prod.google.com ([2002:a17:90a:c088:b0:398:ba84:67d7]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:17c8:b0:396:65dd:4093 with SMTP id 98e67ed59e1d1-39dec04f9d9mr6872853a91.14.1789409550513; Mon, 14 Sep 2026 11:12:30 -0700 (PDT) Reply-To: Sean Christopherson Date: Mon, 14 Sep 2026 11:12:23 -0700 In-Reply-To: <20260914181223.289061-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260914181223.289061-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.1032.g73a4cd73de-goog Message-ID: <20260914181223.289061-6-seanjc@google.com> Subject: [PATCH 5/5] KVM: WARN if vCPU creation is in-progress when locking all vCPUs From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, 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) { -- 2.55.0.1032.g73a4cd73de-goog