From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f198.google.com (mail-pg1-f198.google.com [209.85.215.198]) (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 6E4894EDCCF for ; Mon, 21 Sep 2026 17:44:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790012696; cv=none; b=uO1avVdG9nxi8rEXx/zay1hItwdF8s6/WJ0a6zIjiIVdsHJQksyc9OIyvHGQCCOzhUiRIvEyc48uSRgHYQ2XFNgWFjdR4i+kLHBZvKYdlS1I4t49SFaR4/jO07bxTR1otZ36kNkOrjta/9IUsPC4UpsLBcyOnSSDXR4vShsOGss= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790012696; c=relaxed/simple; bh=ZDfXvDacTET7r9tcukRk54MywQ4no29qxUUGATskm7w=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Q943NAllL7ByJRjMotY/Rc/vih4b63riOhVANHp4wBjHY87c5rycocvYujK3bFZALff+Z7AX5GZl1kn4GBdrwJkN2/uSyfXpv9CYpE1SVJL21aJFLLy5Yl6wTFxsL9MTnWNzWv+HtqLF4gaqUFnH5tzXv0cxIThgwCp5NP0jQEc= 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=LXiMJw6A; arc=none smtp.client-ip=209.85.215.198 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="LXiMJw6A" Received: by mail-pg1-f198.google.com with SMTP id 41be03b00d2f7-cc44d708055so517072a12.0 for ; Mon, 21 Sep 2026 10:44:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1790012693; x=1790617493; 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=QYiGmxrgAXU1trJ4S0lv2S3WvlXO7vDS7xlQ1HDVynU=; b=LXiMJw6A8Tzz/1EryXmvX+JnXBUSozVDbj5asA1QESKMdDoASTeNze+wxAezArHvqz kYBmtNabltlxMt9+q/NplqVUO2kGRM4yLLqbrTw3XI88sVa8xJ3pJl60yHvqfF0ZGLs4 k3+k6S1WCNwA7pVplxIaX9cP2Q/TDDX6HfW3ztz9BMT6Cd5o4/IzdMTjlb3cSn+jnDTJ tbQgs7k5o5TGV0x1lsZjOWSgQjOIWCVqPXjohRRGdpxGv5PLRsOAD1+pGy7iojk7ped8 qNxqGomWN4ghDirIraF/Eo/Gh4ZGBtoZnlpx4NTJXVzsiuwSBFOOBjJkLlcCGU107klp rRPQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790012693; x=1790617493; 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=QYiGmxrgAXU1trJ4S0lv2S3WvlXO7vDS7xlQ1HDVynU=; b=TdrTEeyCh4jA74L35sS2HSDS6zMnJfMu4P8jFz0358hOG+qVncJaN7RYLT45OByUBR vRccj/mhY+rAFOxrLnQKsvVlMMGigh3Nc1RgdkvprEh7xnNkqul0Xkqz1aOX+F1zZOET pqhR3eY6MV2vkhWbktSTNdM/T1umJC+awPvV8GUR28COOny4OAjplvfdocNj/sKXoBLP mQTon5dO6n1nNbKj3tzklaYWtH8A4UecW/OFamJZEszksPQslcBqhq5a/F1A9xiMw1TE TPR1Hb9ANrwI+XR4pPo1AcmR6rfhJ4ANpVi6TB6NDuhX8PijZM3IbnXPQYhxe5hoDZK0 vLPQ== X-Forwarded-Encrypted: i=1; AKwUvBzBpGJ1eJSP2XtrjmLBUzu/mcJClxwTngNKfwyXfWtYQKhB7DJI9obntbayEzhV+Yn8rnMmzrQIms4aIFk=@vger.kernel.org X-Gm-Message-State: AFuF++mO/mHgHaiMbdwrbWam3GGGmmt305DNprxBPxSruEnJ3z4Cl8DP ifOO7ybBm3ra8uw4mPItaskv63HujUCdmS+GMwnDeoatLL3jZqkDJ9zEqgVQK6UiU+56OcDhtUz p8PRFVQ== X-Received: from pfbhu19.prod.google.com ([2002:a05:6a00:6993:b0:879:55dd:922d]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:ad89:b0:85f:3d78:79cc with SMTP id d2e1a72fcca58-874dc4ed21dmr15528120b3a.9.1790012693049; Mon, 21 Sep 2026 10:44:53 -0700 (PDT) Reply-To: Sean Christopherson Date: Mon, 21 Sep 2026 10:44:43 -0700 In-Reply-To: <20260921174445.911676-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260921174445.911676-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog Message-ID: <20260921174445.911676-6-seanjc@google.com> Subject: [PATCH v2 5/7] KVM: Move check for existing vCPU ID to the top of vCPU creation 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->lock is held for the entirety of vCPU creation, check for a conflicting vCPU ID at the begnning of vCPU creation, before the arch precreate() hook is invoked. This will allow reverting commit 97d65b544f48 ("KVM: Check for duplicate vcpu_id as early as possible"). For now, keep the redundant vcpu_ids tracking as a sanity check. No functional change intended (absent KVM bugs, checking vcpu_ids and walking kvm_get_vcpu_by_id() should yield the same result). Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index c17cc8dd371b..d5524ac8c5cf 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4182,7 +4182,10 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, unsigned long id) if (kvm->created_vcpus >= kvm->max_vcpus) return -EINVAL; - if (test_bit(id, kvm->vcpu_ids)) + if (kvm_get_vcpu_by_id(kvm, id)) + return -EEXIST; + + if (WARN_ON_ONCE(test_bit(id, kvm->vcpu_ids))) return -EEXIST; r = kvm_arch_vcpu_precreate(kvm, id); @@ -4221,11 +4224,6 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, unsigned long id) goto arch_vcpu_destroy; } - if (WARN_ON_ONCE(kvm_get_vcpu_by_id(kvm, id))) { - r = -EEXIST; - goto unlock_vcpu_destroy; - } - /* * Set the vCPU's index *before* the vCPU is reachable by other tasks. * Unwind the index back to -1 on failure so that KVM can use the index -- 2.55.0.1082.g2b9226bbc0-goog