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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 24C5BC433FF for ; Fri, 9 Aug 2019 18:55:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 09ACD214C6 for ; Fri, 9 Aug 2019 18:55:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726528AbfHISzZ (ORCPT ); Fri, 9 Aug 2019 14:55:25 -0400 Received: from mga14.intel.com ([192.55.52.115]:58709 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726189AbfHISzZ (ORCPT ); Fri, 9 Aug 2019 14:55:25 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Aug 2019 11:55:24 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,366,1559545200"; d="scan'208";a="326706151" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.41]) by orsmga004.jf.intel.com with ESMTP; 09 Aug 2019 11:55:24 -0700 Date: Fri, 9 Aug 2019 11:55:24 -0700 From: Sean Christopherson To: Vitaly Kuznetsov Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , Joerg Roedel , Jim Mattson Subject: Re: [PATCH v3 7/7] x86: KVM: svm: eliminate hardcoded RIP advancement from vmrun_interception() Message-ID: <20190809185524.GG10541@linux.intel.com> References: <20190808173051.6359-1-vkuznets@redhat.com> <20190808173051.6359-8-vkuznets@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190808173051.6359-8-vkuznets@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Aug 08, 2019 at 07:30:51PM +0200, Vitaly Kuznetsov wrote: > Just like we do with other intercepts, in vmrun_interception() we should be > doing kvm_skip_emulated_instruction() and not just RIP += 3. Also, it is > wrong to increment RIP before nested_svm_vmrun() as it can result in > kvm_inject_gp(). > > We can't call kvm_skip_emulated_instruction() after nested_svm_vmrun() so > move it inside. To preserve the return value from it nested_svm_vmrun() > needs to start returning an int. > > Suggested-by: Sean Christopherson > Signed-off-by: Vitaly Kuznetsov > --- > arch/x86/kvm/svm.c | 27 ++++++++++++--------------- > 1 file changed, 12 insertions(+), 15 deletions(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 43bc4a5e4948..6c4046eb26b3 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -3586,9 +3586,9 @@ static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa, > mark_all_dirty(svm->vmcb); > } > > -static bool nested_svm_vmrun(struct vcpu_svm *svm) > +static int nested_svm_vmrun(struct vcpu_svm *svm) > { > - int rc; > + int rc, ret; > struct vmcb *nested_vmcb; > struct vmcb *hsave = svm->nested.hsave; > struct vmcb *vmcb = svm->vmcb; > @@ -3598,12 +3598,15 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm) > vmcb_gpa = svm->vmcb->save.rax; > > rc = kvm_vcpu_map(&svm->vcpu, gpa_to_gfn(vmcb_gpa), &map); > - if (rc) { > - if (rc == -EINVAL) > - kvm_inject_gp(&svm->vcpu, 0); > - return false; > + if (rc == -EINVAL) { > + kvm_inject_gp(&svm->vcpu, 0); > + return 1; > } > > + ret = kvm_skip_emulated_instruction(&svm->vcpu); > + if (rc) > + return ret; This should probably have a comment, the 'if (rc)' looks so wrong at first glance. Maybe not the best suggestion on my part... Alternatively, this sequence is more obvious and at worst adds a few bytes to the code footprint. if (ret == EINVAL) { kvm_inject_gp(&svm->vcpu, 0); return 1; } else if (ret) { return kvm_skip_emulated_instruction(&svm->vcpu); } ret = kvm_skip_emulated_instruction(&svm->vcpu); > + > nested_vmcb = map.hva; > > if (!nested_vmcb_checks(nested_vmcb)) { > @@ -3614,7 +3617,7 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm) > > kvm_vcpu_unmap(&svm->vcpu, &map, true); > > - return false; > + return ret; > } > > trace_kvm_nested_vmrun(svm->vmcb->save.rip, vmcb_gpa, > @@ -3667,7 +3670,7 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm) > nested_svm_vmexit(svm); > } > > - return true; > + return ret; > } > > static void nested_svm_vmloadsave(struct vmcb *from_vmcb, struct vmcb *to_vmcb) > @@ -3743,13 +3746,7 @@ static int vmrun_interception(struct vcpu_svm *svm) > if (nested_svm_check_permissions(svm)) > return 1; > > - /* Save rip after vmrun instruction */ > - kvm_rip_write(&svm->vcpu, kvm_rip_read(&svm->vcpu) + 3); > - > - if (!nested_svm_vmrun(svm)) > - return 1; > - > - return 1; > + return nested_svm_vmrun(svm); > } > > static int stgi_interception(struct vcpu_svm *svm) > -- > 2.20.1 >