From patchwork Mon Feb 24 09:09:59 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: 13987631 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 803D924BBE4 for ; Mon, 24 Feb 2025 09:10:14 +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=1740388214; cv=none; b=qaQOibX7C5NVo6oG3tTAU/ykAaiw4PMXIkRQ5umdaNjiJjZDvGrrOkK4uId/dPu1+g7RELPCT9mlDhrfR2JrUkUZDQqRHg6ij+B9j/RJmV0gekdwQv2+4VisUNSheb1RFHRUE/QMlowQQUtmy9FDSbJ36+y8Esn2gCmGESoEWTc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740388214; c=relaxed/simple; bh=d89GjCOAb8v1g8rv/GObFnQoi4giK3ojT0tAF8KaSkM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=gy14Cndi5MV6iFTHV0OuZ7eWQp9nq2sHlKxO2smOi20sekWzGp5xKI9QIh05XoL3ctOO39uTKpcGcfk73VM2bLa5gaFrztiQdFsftbx5mvs5LeStk/EBe4WED4k0KQj4s2On1IQMqrDhYX91zoNZgUoggr2dqa+mbmye3+wrex4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GD9/klwW; 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="GD9/klwW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D2CDC4CEDD; Mon, 24 Feb 2025 09:10:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740388214; bh=d89GjCOAb8v1g8rv/GObFnQoi4giK3ojT0tAF8KaSkM=; h=From:To:Cc:Subject:Date:From; b=GD9/klwWJcjF7oPGb8bOec5XsGUAPU5bFsNXX1X/rRGqJZveSgIe6r6vLdbIbXfu8 N1hXaXmopqi7EhUw8T7NodmBcltwxkGJFzgNIb72rV67edLEyJY49zYf0anp0huEEh XVJji0CSx/nOdjGRDi6q/iCL5xk6AwYGHqWhFUdiA/JF+1y1i//U/35FAqjLEsA/B3 GujlEOHLA3ys8RVDqVRTobigzuBCHGJ/APbonXmoHP0TWy3U1ywsXqJP+lhwqS25Ml vE3b7Jqz6LnoWMHad1zBJrhPypEzFRWwWV2PTfsjkD0X9I66T11A2YvroOyMKi2i1y dSnbgecDp3V9w== From: "Aneesh Kumar K.V (Arm)" To: kvm@vger.kernel.org Cc: Suzuki K Poulose , Steven Price , Will Deacon , Julien Thierry , Alexandru Elisei , "Aneesh Kumar K.V (Arm)" Subject: [PATCH kvmtool v2 1/2] cpu: vmexit: Handle KVM_EXIT_UNKNOWN exit reason correctly Date: Mon, 24 Feb 2025 14:39:59 +0530 Message-ID: <20250224091000.3925918-1-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 kernel VM exit handlers 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 VMM exit with error on KVM_EXIT_UNKNOWN exit_reson would help catch these bugs early. Signed-off-by: Aneesh Kumar K.V (Arm) Reviewed-by: Alexandru Elisei --- kvm-cpu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kvm-cpu.c b/kvm-cpu.c index f66dcd07220c..7c62bfc56679 100644 --- a/kvm-cpu.c +++ b/kvm-cpu.c @@ -170,7 +170,7 @@ int kvm_cpu__start(struct kvm_cpu *cpu) switch (cpu->kvm_run->exit_reason) { case KVM_EXIT_UNKNOWN: - break; + goto panic_kvm; case KVM_EXIT_DEBUG: kvm_cpu__show_registers(cpu); kvm_cpu__show_code(cpu); From patchwork Mon Feb 24 09:10:00 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: 13987632 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 3BD86243364 for ; Mon, 24 Feb 2025 09:10:18 +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=1740388218; cv=none; b=ggAAoJ7nAgaWUNAeR7OOrf4StR7nTI0e86qQPrrRK6YQXbVhdB4jaw84vI/Vfn77EmMyRzrLB0FJYtZvQzyhlyOPwjI+0B2W3y+G3bB/CazQXOUVSCblbr0Mhtfq0DRakKd7OAOhIJaO0zfb3b7ce+sfB3L4ImnTSAsQ5rSaKMs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740388218; c=relaxed/simple; bh=25WXkM/8rWEaoR8LFVp2KbNEahjJte6M9YZgoly96/k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QZKlJ2i6m0zuJpxqvy54LIsV2TeEV0skY1ef9zmOjE5QkprsYanWwcr2DG9rbSLDNnASA64/3vZwXlfbELibyn7zh/vOyQWRGeJSMse7Rfc1DbS3CYGj5NZ6oiH+Rw68JdCE1VF6wGt9RHEnoMBnRFyWH+OTyWy9VBO/2+a2WOg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qpzZXn8L; 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="qpzZXn8L" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 26196C4CED6; Mon, 24 Feb 2025 09:10:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740388218; bh=25WXkM/8rWEaoR8LFVp2KbNEahjJte6M9YZgoly96/k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qpzZXn8L1aQBqOsvb+yp/83lYCIJyb70RwcmdBiwXcxpdAg52ilg5B7wSCx8SEoZb qLqxnFHjdNqS+yz2YD0r4EoNboQCFNK4SpMumjVmpQzli70bmSz8/prZV6Duebd4or O3R3cClzegFyUcE9e6MEGS/PYRhHMJQ0QVjAQ8EgynerK4ambFJ+OP63pQFuRWPvyV UbVk5I9YxrWA9HXB2hu+Fnzw9+ZwCa29OJZ0ZymsDz4tmr7ZtMBdVLwMr75TL2jbhM 93JM0+3UmG8OHrGn7eM+TFk8CVGcNTYHuJYhS3KfVY0Yo3Yoxgq2/SA88IyVy+sxVg 4LqgCzIwgTBWg== From: "Aneesh Kumar K.V (Arm)" To: kvm@vger.kernel.org Cc: Suzuki K Poulose , Steven Price , Will Deacon , Julien Thierry , Alexandru Elisei , "Aneesh Kumar K.V (Arm)" Subject: [PATCH kvmtool v2 2/2] cpu: vmexit: Handle KVM_EXIT_MEMORY_FAULT in KVM_RUN ioctl return Date: Mon, 24 Feb 2025 14:40:00 +0530 Message-ID: <20250224091000.3925918-2-aneesh.kumar@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250224091000.3925918-1-aneesh.kumar@kernel.org> References: <20250224091000.3925918-1-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 KVM_RUN ioctl error handling to correctly handle KVM_EXIT_MEMORY_FAULT. This enables the memory fault exit handlers in the kernel to return -EFAULT as the return value. VMM support is still required to handle these memory fault exits, but that is not included in this change Signed-off-by: Aneesh Kumar K.V (Arm) Reviewed-by: Alexandru Elisei --- kvm-cpu.c | 15 +++++++++++++-- kvm.c | 1 + 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/kvm-cpu.c b/kvm-cpu.c index 7c62bfc56679..c0b10b1534ab 100644 --- a/kvm-cpu.c +++ b/kvm-cpu.c @@ -41,8 +41,19 @@ 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) { + switch (errno) { + case EINTR: + case EAGAIN: + return; + case EFAULT: + if (vcpu->kvm_run->exit_reason == KVM_EXIT_MEMORY_FAULT) + return; + /* faullthrough */ + default: + die_perror("KVM_RUN failed"); + } + } } static void kvm_cpu_signal_handler(int signum) diff --git a/kvm.c b/kvm.c index 42b881217df6..172d951bfe4e 100644 --- a/kvm.c +++ b/kvm.c @@ -55,6 +55,7 @@ const char *kvm_exit_reasons[] = { #ifdef CONFIG_PPC64 DEFINE_KVM_EXIT_REASON(KVM_EXIT_PAPR_HCALL), #endif + DEFINE_KVM_EXIT_REASON(KVM_EXIT_MEMORY_FAULT), }; static int pause_event;