From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77599C4360F for ; Tue, 2 Apr 2019 20:30:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 365392075E for ; Tue, 2 Apr 2019 20:30:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726168AbfDBUaT (ORCPT ); Tue, 2 Apr 2019 16:30:19 -0400 Received: from mga12.intel.com ([192.55.52.136]:34142 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725812AbfDBUaT (ORCPT ); Tue, 2 Apr 2019 16:30:19 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 02 Apr 2019 13:30:16 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,302,1549958400"; d="scan'208";a="333164073" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.181]) by fmsmga006.fm.intel.com with ESMTP; 02 Apr 2019 13:30:15 -0700 Date: Tue, 2 Apr 2019 13:30:15 -0700 From: Sean Christopherson To: Yang Weijiang Cc: pbonzini@redhat.com, kvm@vger.kernel.org, mst@redhat.com, rkrcmar@redhat.com, jmattson@google.com, linux-kernel@vger.kernel.org, yu-cheng.yu@intel.com, Zhang Yi Z Subject: Re: [RFC PATCH v4 5/8] KVM:VMX: Load Guest CET via VMCS when CET is enabled in Guest Message-ID: <20190402203014.GJ31303@linux.intel.com> References: <20190318150351.15550-1-weijiang.yang@intel.com> <20190318150351.15550-6-weijiang.yang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190318150351.15550-6-weijiang.yang@intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 18, 2019 at 11:03:48PM +0800, Yang Weijiang wrote: > "Load Guest CET state" bit controls whether guest CET states > will be loaded at Guest entry. Before doing that, KVM needs > to check if CPU CET feature is available. Use the changelog to describe *why* the patch does what it does, for something this simple it's obvious *what* the patch adds. Specifically, there was a decent amount of discussion regarding the virtualization hole that gets introduced when SHSTK!=IBT, and that need to be captured in the changelog. > > Signed-off-by: Zhang Yi Z > Signed-off-by: Yang Weijiang > --- > arch/x86/kvm/vmx.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 28b8ac027bd7..246467c12930 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -55,6 +55,7 @@ > #include > #include > #include > +#include > > #include "trace.h" > #include "pmu.h" > @@ -5414,6 +5415,23 @@ static int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) > return 1; > } > > + /* > + * To enable Guest CET, check whether CPU CET feature is > + * available, if it's there, set Guest CET state loading bit > + * per CR4.CET status, otherwise, return a fault to Guest. > + */ No need for the comment, the code is straightforward. > + if (guest_cpuid_has(vcpu, X86_FEATURE_SHSTK) || > + guest_cpuid_has(vcpu, X86_FEATURE_IBT)) { > + if (cr4 & X86_CR4_CET) > + vmcs_set_bits(VM_ENTRY_CONTROLS, > + VM_ENTRY_LOAD_GUEST_CET_STATE); > + else > + vmcs_clear_bits(VM_ENTRY_CONTROLS, > + VM_ENTRY_LOAD_GUEST_CET_STATE); > + } else if (cr4 & X86_CR4_CET) { > + return 1; > + } > + > if (to_vmx(vcpu)->nested.vmxon && !nested_cr4_valid(vcpu, cr4)) > return 1; > > -- > 2.17.1 >