From mboxrd@z Thu Jan 1 00:00:00 1970 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 CD894260A30 for ; Tue, 11 Feb 2025 16:56:14 +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=1739292974; cv=none; b=HkojgD8W/0hBzDafjvsZd2TN+wQJb6fFoA8pIrbnJ9M4tm8DrdZBfBaQkgoNpW3Lao4yUV8yBgcndoZ44F9ZeZ+s0eEvLxCFXYsCHvTtRJQiIPKoLiPNwxtaceK9PqhZMkmCUrucvm0Biog7TZCkZihtUt1ITGvl4sfTQuP4GyQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739292974; c=relaxed/simple; bh=o9ip2gqZhd0xWo4DIa77rdAvzY616OX7OjtJIkIrKp0=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=bN09IPCu/JS3XuwTShdaYerHQZjReWU08UPqJ4+fvHhNagEC78dD+BTuNlhq0dFw/zQk3l97xzM89wrW5SlxNhgq72LwWaP/veH8lSvkQ34K/toolwTvqRRIhk43vS2six3fMYeFJYal4Ze/4cIaM8GpFu6qf5iaeSPV3/g3cd8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nZr8NvxJ; 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="nZr8NvxJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96313C4CEDD; Tue, 11 Feb 2025 16:56:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739292974; bh=o9ip2gqZhd0xWo4DIa77rdAvzY616OX7OjtJIkIrKp0=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=nZr8NvxJ6mziz6Q6fMKIFsClEJ2b20Alq3gvqdlxAnRAkTwPG5D6z4jhDXt1yfjzv wAeCOxQAyR53AeGuc4J//Ah3XexfF9j+n/E/Rjxz9mQ/77Sxr6SZC4mKbv8RNasmjC olfYITgVULz97AriqWWw5mU70oOnUyQ7gXNxFycSa79FXXaGPQBaE0/YL9/IBQYcYV u8SEZ0IR6XeB5ah6GpiA3JmHDIEAvz0cBmq0+Zt7KBS/Ub8fQqWYjyY8D42MGU1kSY Y6hEYYapNlOKdYBoPsd2+Y84eLdRiruKLHiRKUvPmFUVJrPndtcvC/UIDSr+edGLdF 0mPUMwaWSIL4w== X-Mailer: emacs 31.0.50 (via feedmail 11-beta-1 I) From: Aneesh Kumar K.V To: Will Deacon Cc: kvm@vger.kernel.org, Suzuki K Poulose , Steven Price , Julien Thierry Subject: Re: [PATCH kvmtool 2/2] cpu: vmexit: Handle KVM_EXIT_MEMORY_FAULT correctly In-Reply-To: <20250211114848.GD8965@willie-the-truck> References: <20250211073852.571625-1-aneesh.kumar@kernel.org> <20250211073852.571625-2-aneesh.kumar@kernel.org> <20250211114848.GD8965@willie-the-truck> Date: Tue, 11 Feb 2025 22:26:08 +0530 Message-ID: Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Will Deacon writes: > On Tue, Feb 11, 2025 at 01:08:52PM +0530, Aneesh Kumar K.V (Arm) wrote: >> 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"); >> + } > > Probably cleaner to switch on errno? This? . I will update. if (err < 0) { switch (errno) { case EINTR: case EAGAIN: return; case EFAULT: if (vcpu->kvm_run->exit_reason == KVM_EXIT_MEMORY_FAULT) return; /* fallthrough */ default: die_perror("KVM_RUN failed"); } } -aneesh