From patchwork Tue Feb 11 07:38:51 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Aneesh Kumar K.V" X-Patchwork-Id: 13970138 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B8E3A1E3DF7 for ; Tue, 11 Feb 2025 07:39:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739259559; cv=none; b=i+6y2FleTUJJlL25kq8csbiaNeCA/eAaln+NgfzkU1MqYKpEVh6zT3o9gk0za+9E8TIz9DqXpDZBqnbYhobR0PngnAGKf+LcRdNTkQY7Bot0SvrfV4p8hN6347J3NAS5J45JZL9I2p/mn68yl9StjBDzspRKmfA5W3+OkVzouFA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739259559; c=relaxed/simple; bh=gR66WKwXquY3P4hJ2/qAS/d9cRt+fUhpHJrGfvKW5Hk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=mwwXQBIBGlKnDDmUEh9H2KOHaf9mXh9tLlSR4KOqZ13D+PHsGrTeIhkOhi+Hy3L5ABJ1+Yz91HH+AtM/sz/wya0pyXB/tOWvjIgLAiwk+SJ2aHBbUCS4P/p42gRmQbMPLJfE2SvN8+kvoia56x8/Qs14UUXhWbUEigXWMnFxwXE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=R0fN9WZv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="R0fN9WZv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9533C4CEDD; Tue, 11 Feb 2025 07:39:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739259558; bh=gR66WKwXquY3P4hJ2/qAS/d9cRt+fUhpHJrGfvKW5Hk=; h=From:To:Cc:Subject:Date:From; b=R0fN9WZvmkCcDKIqMS8OS6CItxZV8UB/OZohx5OtiRr5n0lqtFmF022D+zixIgQBY A1NSH6TbulfC8GTFqUpF2Pi0N8TStfZW3EdVy339ONQDVSObnmxPdACd+8q5gbjzq/ WsJbJZvtEqp5fY+REKNMoSoTsEBvpyz1Fo5EgbqD5wZQgA6c/O/N3xfuBuHe+tEOL/ vXd0UHDUZr2SWsm7NeIHDon4PHNGMLb43cH8IyhwpcV0448Zjvt/JRyoLyoDiNfGsv IbNtoCF+XAVcO+G/MePKPrqC9ngUADIiQt9iYM8AcItmOSMf5UPYOdNlE9a9ErjsGD 9rJiVskRkE5oA== From: "Aneesh Kumar K.V (Arm)" To: kvm@vger.kernel.org Cc: Suzuki K Poulose , Steven Price , Will Deacon , Julien Thierry , "Aneesh Kumar K.V (Arm)" Subject: [PATCH kvmtool 1/2] cpu: vmexit: Handle KVM_EXIT_UNKNOWN exit reason correctly Date: Tue, 11 Feb 2025 13:08:51 +0530 Message-ID: <20250211073852.571625-1-aneesh.kumar@kernel.org> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The return value for the KVM_RUN ioctl is confusing and has led to errors in different kernel exit handlers. A return value of 0 indicates a return to the VMM, whereas a return value of 1 indicates resuming execution in the guest. Some handlers mistakenly return 0 to force a return to the guest. This worked in kvmtool because the exit_reason defaulted to 0 (KVM_EXIT_UNKNOWN), and kvmtool did not error out on an unknown exit reason. However, forcing a KVM panic on an unknown exit reason would help catch these bugs early. Signed-off-by: Aneesh Kumar K.V (Arm) --- kvm-cpu.c | 1 + 1 file changed, 1 insertion(+) base-commit: 6d754d01fe2cb366f3b636d8a530f46ccf3b10d8 diff --git a/kvm-cpu.c b/kvm-cpu.c index f66dcd07220c..66e30ba54e26 100644 --- a/kvm-cpu.c +++ b/kvm-cpu.c @@ -170,6 +170,7 @@ int kvm_cpu__start(struct kvm_cpu *cpu) switch (cpu->kvm_run->exit_reason) { case KVM_EXIT_UNKNOWN: + goto panic_kvm; break; case KVM_EXIT_DEBUG: kvm_cpu__show_registers(cpu); From patchwork Tue Feb 11 07:38:52 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Aneesh Kumar K.V" X-Patchwork-Id: 13970139 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 997FB1E3DF7 for ; Tue, 11 Feb 2025 07:39:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739259561; cv=none; b=tUHtVWNs+rtrF0PpBfwx/R8Rt1bG2tW6CTSH8/IEhwSDVIcbXvDqx1ftVLB55Svlwl4MHeqMUbUJP9l+nFLVsbDq798AAIxTwQ2qrsOIFDxPBPoQxGIkvuN048ENYkEHntzeToiCNCF7roDyJxU58FTpZXd+dU0dMjfZt3etbLs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739259561; c=relaxed/simple; bh=plMMkduv0ZvGwS/5ylyV0jdc4BYwhmtmmWjE218aJlM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=W0kEYsF9hNIz0AAkHPpD/jnST69S37jMrAXAMsShSIX310ZJ3o+HHH7tJxs2sWsp/rj/gcuMA+yp4nuRA6CPfk4v7zILvTR6UF4K27QTaYNzlyG1s3MaZwRtxiVjnqL6QXtGxKr4Z84JGTH+JOPIPqfEZ3XdHgs30j0ZXStrCD4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=r+LlErX5; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="r+LlErX5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C5AEFC4CEE6; Tue, 11 Feb 2025 07:39:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739259561; bh=plMMkduv0ZvGwS/5ylyV0jdc4BYwhmtmmWjE218aJlM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=r+LlErX5VIR+dAzpYT8Exj8Jjrf8Tjf0G7md9P+zpjDMfYMdjduOzt38H6sopvC2E sRGmURwdYlEvG1gUgjwEcf2ZbszIyBdynb0nKXryvOQgYtLJDF24xz/+x8QGUpm0Ik 6u0ilqdDzM3rqG1MvDjgJVqvWgoCu6fdEw2Wp21OobDa4GKj4JZMi42blGrbhft8KM OYuMc0jEKctqkx5Xjt5ADLkKMKJsPxHZ0b1N5jVDqQqymdLng3GfQOAFx5t8dZvvtO WnTjmElteOe2I7y6ZkBmevJeljgUiNrfhccfmgJTBZjnn5/yDZPsXN6QnVaKiRHxI2 fnBi0aa7LfL6w== From: "Aneesh Kumar K.V (Arm)" To: kvm@vger.kernel.org Cc: Suzuki K Poulose , Steven Price , Will Deacon , Julien Thierry , "Aneesh Kumar K.V (Arm)" Subject: [PATCH kvmtool 2/2] cpu: vmexit: Handle KVM_EXIT_MEMORY_FAULT correctly Date: Tue, 11 Feb 2025 13:08:52 +0530 Message-ID: <20250211073852.571625-2-aneesh.kumar@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250211073852.571625-1-aneesh.kumar@kernel.org> References: <20250211073852.571625-1-aneesh.kumar@kernel.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Linux kernel documentation states: "Note! KVM_EXIT_MEMORY_FAULT is unique among all KVM exit reasons in that it accompanies a return code of '-1', not '0'! errno will always be set to EFAULT or EHWPOISON when KVM exits with KVM_EXIT_MEMORY_FAULT, userspace should assume kvm_run.exit_reason is stale/undefined for all other error numbers." " Update the KVM_RUN ioctl error handling to correctly handle KVM_EXIT_MEMORY_FAULT. Signed-off-by: Aneesh Kumar K.V (Arm) --- kvm-cpu.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/kvm-cpu.c b/kvm-cpu.c index 66e30ba54e26..40e4efc33a1d 100644 --- a/kvm-cpu.c +++ b/kvm-cpu.c @@ -41,8 +41,15 @@ void kvm_cpu__run(struct kvm_cpu *vcpu) return; err = ioctl(vcpu->vcpu_fd, KVM_RUN, 0); - if (err < 0 && (errno != EINTR && errno != EAGAIN)) - die_perror("KVM_RUN failed"); + if (err < 0) { + if (errno == EINTR || errno == EAGAIN) + return; + else if (errno == EFAULT && + vcpu->kvm_run->exit_reason == KVM_EXIT_MEMORY_FAULT) + return; + else + die_perror("KVM_RUN failed"); + } } static void kvm_cpu_signal_handler(int signum)