From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752519AbdHKGN5 (ORCPT ); Fri, 11 Aug 2017 02:13:57 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:35358 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752406AbdHKGNz (ORCPT ); Fri, 11 Aug 2017 02:13:55 -0400 Subject: Re: [PATCH] KVM: MMU: Fix guest stuck during boot due to read/write emulation against GVA To: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Wanpeng Li , Brijesh Singh References: <1502431194-3636-1-git-send-email-wanpeng.li@hotmail.com> From: Paolo Bonzini Message-ID: Date: Fri, 11 Aug 2017 08:13:50 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <1502431194-3636-1-git-send-email-wanpeng.li@hotmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/08/2017 07:59, Wanpeng Li wrote: > From: Wanpeng Li > > Commit c016004494b0 (KVM: x86: Avoid guest page table walk when gpa_available > is set) avoids the page table walk when cr2 has already contained a valid GPA. > However, that is not the truth if ept == 0 and shadow page table is used. In > this scenario cr2 can just contains a valid GVA. The commit results in guest > stuck during boot due to read/write emulation against GVA instead of GPA of > the guest. > > This patch fixes it by not setting the gpa_available flag if the shadow page table > is used. Yup, I got these on my overnight tests too. A better fix that I was going to commit today is: if (vcpu->arch.mmu.direct_map) { vcpu->arch.gpa_available = true; vcpu->arch.gpa_val = fault_address; } because AMD gets here even if npt=1. Paolo > Cc: Paolo Bonzini > Cc: Radim Krčmář > Cc: Brijesh Singh > Signed-off-by: Wanpeng Li > --- > arch/x86/kvm/mmu.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 849312d..e4ce20b 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -3791,8 +3791,6 @@ int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code, > > if (need_unprotect && kvm_event_needs_reinjection(vcpu)) > kvm_mmu_unprotect_page_virt(vcpu, fault_address); > - vcpu->arch.gpa_available = true; > - vcpu->arch.gpa_val = fault_address; > r = kvm_mmu_page_fault(vcpu, fault_address, error_code, insn, > insn_len); > break; >