From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754254AbeBGOQy (ORCPT ); Wed, 7 Feb 2018 09:16:54 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:60278 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753796AbeBGOQw (ORCPT ); Wed, 7 Feb 2018 09:16:52 -0500 Subject: Re: [PATCH] KVM: X86: Fix SMRAM accessing even if VM is shutdown To: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Dmitry Vyukov References: <1517984706-47244-1-git-send-email-wanpengli@tencent.com> From: Paolo Bonzini Message-ID: <233cfca3-971e-c3c2-f0fe-b50dd69d2546@redhat.com> Date: Wed, 7 Feb 2018 15:16:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <1517984706-47244-1-git-send-email-wanpengli@tencent.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 07/02/2018 07:25, Wanpeng Li wrote: > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 786cd00..445e702 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -7458,6 +7458,11 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) > goto out; > } > > + if (unlikely(vcpu->run->exit_reason == KVM_EXIT_SHUTDOWN)) { > + r = -EINVAL; > + goto out; > + } > + > if (vcpu->run->kvm_dirty_regs) { > r = sync_regs(vcpu); > if (r != 0) > This most likely breaks triple faults in the usual case where they should result in resetting the system; the KVM API doesn't say that you should clear vcpu->run->exit_reason before entering. What exactly causes the EPT misconfig to reach the WARN? That is, how does kvm_mmu_page_fault end up returning a negative errno value? If I read the code correctly only tdp_page_fault can do so, so my guess would be kvm_handle_bad_page: if (pfn == KVM_PFN_ERR_RO_FAULT) return RET_PF_EMULATE; if (pfn == KVM_PFN_ERR_HWPOISON) { kvm_send_hwpoison_signal(kvm_vcpu_gfn_to_hva(vcpu, gfn), current); return RET_PF_RETRY; } /* KVM_PFN_ERR_FAULT */ return -EFAULT; Maybe it should return RET_PF_EMULATE, which would cause an emulation failure and then an exit with KVM_EXIT_INTERNAL_ERROR. Thanks, Paolo