From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752302AbaCJIyG (ORCPT ); Mon, 10 Mar 2014 04:54:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45309 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751675AbaCJIyD (ORCPT ); Mon, 10 Mar 2014 04:54:03 -0400 Message-ID: <531D7DA5.4020002@redhat.com> Date: Mon, 10 Mar 2014 09:53:57 +0100 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: "Liu, Jinsong" , "'kvm@vger.kernel.org'" , "'linux-kernel@vger.kernel.org'" , "'qemu-devel@nongnu.org'" Subject: Re: [PATCH] KVM: x86: Work around buggy MPX platform References: In-Reply-To: X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 10/03/2014 09:48, Liu, Jinsong ha scritto: > From 5854070994c5002b3a37577165ed3e82f36f712d Mon Sep 17 00:00:00 2001 > From: Liu Jinsong > Date: Sat, 8 Mar 2014 04:40:02 +0800 > Subject: [PATCH] KVM: x86: Work around buggy MPX platform > > Work around buggy MPX platform which support MSR_IA32_BNDCFGS > but has issue at, say, VMX ucode. > > Signed-off-by: Liu Jinsong > --- > arch/x86/kvm/x86.c | 14 +++++++++++++- > 1 files changed, 13 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 1e91a24..1fc184d 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3936,6 +3936,16 @@ static void kvm_init_msr_list(void) > for (i = j = KVM_SAVE_MSRS_BEGIN; i < ARRAY_SIZE(msrs_to_save); i++) { > if (rdmsr_safe(msrs_to_save[i], &dummy[0], &dummy[1]) < 0) > continue; > + > + /* > + * Work around some buggy MPX platform which support > + * MSR_IA32_BNDCFGS but has issue at, say, VMX ucode. > + */ > + if ((msrs_to_save[i] == MSR_IA32_BNDCFGS) && Too many parentheses in this "if". > + (kvm_x86_ops->mpx_supported ? > + !kvm_x86_ops->mpx_supported() : 1)) Better: "!kvm_x86_ops->mpx_supported || !kvm_x86_ops->mpx_supported()" but I'm leaning towards adding an implementation of mpx_supported to SVM too (it will always return false). > + continue; > + > if (j < i) > msrs_to_save[j] = msrs_to_save[i]; > j++; > @@ -5576,9 +5586,11 @@ int kvm_arch_init(void *opaque) > goto out_free_percpu; > > kvm_set_mmio_spte_mask(); > - kvm_init_msr_list(); > > kvm_x86_ops = ops; > + > + kvm_init_msr_list(); > + > kvm_mmu_set_mask_ptes(PT_USER_MASK, PT_ACCESSED_MASK, > PT_DIRTY_MASK, PT64_NX_MASK, 0); > > Thanks Liu. Indeed I could not reproduce Robert's issue, though it might be possible to get it with nested virtualization. I'll send a similar patch that I was testing. Paolo