Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934364AbdC3QaU (ORCPT ); Thu, 30 Mar 2017 12:30:20 -0400 Received: from mail-wr0-f174.google.com ([209.85.128.174]:32867 "EHLO mail-wr0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754441AbdC3QaT (ORCPT ); Thu, 30 Mar 2017 12:30:19 -0400 MIME-Version: 1.0 In-Reply-To: <1490867732-16743-3-git-send-email-pbonzini@redhat.com> References: <1490867732-16743-1-git-send-email-pbonzini@redhat.com> <1490867732-16743-3-git-send-email-pbonzini@redhat.com> From: Jim Mattson Date: Thu, 30 Mar 2017 09:30:16 -0700 Message-ID: Subject: Re: [PATCH 2/6] KVM: VMX: remove bogus check for invalid EPT violation To: Paolo Bonzini Cc: LKML , kvm list , David Hildenbrand Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2148 Lines: 51 On Thu, Mar 30, 2017 at 2:55 AM, Paolo Bonzini wrote: > handle_ept_violation is checking for "guest-linear-address invalid" + > "not a paging-structure walk". However, _all_ EPT violations without > a valid guest linear address are paging structure walks, because those > EPT violations happen when loading the guest PDPTEs. > > Therefore, the check can never be true, and even if it were, KVM doesn't > care about the guest linear address; it only uses the guest *physical* > address VMCS field. So, remove the check altogether. > > Signed-off-by: Paolo Bonzini The check can never be true because the SDM says so explicitly: Bit 8 is "Reserved if bit 7 is 0 (cleared to 0)." Reviewed-by: Jim Mattson > --- > arch/x86/kvm/vmx.c | 14 -------------- > 1 file changed, 14 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 0e61b9226bf2..1c372600a962 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -6208,23 +6208,9 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu) > unsigned long exit_qualification; > gpa_t gpa; > u32 error_code; > - int gla_validity; > > exit_qualification = vmcs_readl(EXIT_QUALIFICATION); > > - gla_validity = (exit_qualification >> 7) & 0x3; > - if (gla_validity == 0x2) { > - printk(KERN_ERR "EPT: Handling EPT violation failed!\n"); > - printk(KERN_ERR "EPT: GPA: 0x%lx, GVA: 0x%lx\n", > - (long unsigned int)vmcs_read64(GUEST_PHYSICAL_ADDRESS), > - vmcs_readl(GUEST_LINEAR_ADDRESS)); > - printk(KERN_ERR "EPT: Exit qualification is 0x%lx\n", > - (long unsigned int)exit_qualification); > - vcpu->run->exit_reason = KVM_EXIT_UNKNOWN; > - vcpu->run->hw.hardware_exit_reason = EXIT_REASON_EPT_VIOLATION; > - return 0; > - } > - > /* > * EPT violation happened while executing iret from NMI, > * "blocked by NMI" bit has to be set before next VM entry. > -- > 1.8.3.1 > >