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=-9.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 CFF82C35247 for ; Wed, 5 Feb 2020 15:20:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A35BF222D9 for ; Wed, 5 Feb 2020 15:20:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="b5JgSbc6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727043AbgBEPUS (ORCPT ); Wed, 5 Feb 2020 10:20:18 -0500 Received: from mail-wm1-f66.google.com ([209.85.128.66]:37308 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726534AbgBEPUR (ORCPT ); Wed, 5 Feb 2020 10:20:17 -0500 Received: by mail-wm1-f66.google.com with SMTP id f129so3267122wmf.2; Wed, 05 Feb 2020 07:20:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id; bh=Eu/czLrqDMFVqxZHLoEa1l5MyCiw1QB7Y2F2E91wwso=; b=b5JgSbc6vwObcogWIFqOdkOezS9kTXNdfyy/tlLf8DObaHOghHX8McPh9K4mcOiOKB 85UssOj3VIaD1h+nwh5BdeqmGmJDmS5g4U5wkVdxkPjOHz9YJFxJar3htH96Vt7+ayPU WM6ka3hNGbsAWbiknIrYLmhLGQ9Tn0EZBb8Pg/xdCbEaSSz+IyRJhSLGcLfEbmkhngY0 2x6ciCIVfpPBxkOazxKfJoVagfZ7yLz0FGCe/tY3X87XxX/Fx24mHowRqnGy9r3MCW34 yLlEPw+vip+6ianwxrIrlL06NBD4Ihg27IkXdJwZzMQoadZLUZOhx6w80Vu+44E5L53+ 7+ZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id; bh=Eu/czLrqDMFVqxZHLoEa1l5MyCiw1QB7Y2F2E91wwso=; b=XyRMYZl/UVvpu1lZmFBEk9bR5OEF+qvKzm7PAcV+XTHLkYKCxV7QGn1Y8LTKYMiWtp BJUA3DaOrlVdUiV1399Xo7lh2RXK2/kTNczUM6Nu3FTflisY8AfE1kMgz30zpuTOAtdV xTpd3OHi4FMXjhxCgf8zkcLc6TTpfb8p//cRLYl+yKs577DpI0cC90OijE9pt68zclD3 ib+Esfctre7+sVJedLeQloyJJtkHc4C+7s37XO3CFm6MxysED5vLepZFS3e4dGEtRFGI yqH3sFWkx3kR4A6SMkIz6IuSMVFW1rraTSo6kCOoEULD8mRKZnpd8lR49l2LIiC3o+Uz zcWQ== X-Gm-Message-State: APjAAAXTk0LS71sdMpGi3hjsq5Zz7XKme8PegMUqJOA+Dzqxy46w4/oW R9HNm33ueXprBumnDcZrPBCE0EY6 X-Google-Smtp-Source: APXvYqwuVi7TatktuYrcptCy2OsCtreFpYhjY4vsG4aVYW8c+xoZYJfb6LlcgJJA4tkEcMtI/fcZ8A== X-Received: by 2002:a1c:7c08:: with SMTP id x8mr6582758wmc.106.1580915630238; Wed, 05 Feb 2020 07:13:50 -0800 (PST) Received: from 640k.localdomain.com ([93.56.166.5]) by smtp.gmail.com with ESMTPSA id c15sm176452wrt.1.2020.02.05.07.13.49 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Feb 2020 07:13:49 -0800 (PST) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: dgilbert@redhat.com, jmattson@google.com Subject: [PATCH] KVM: SVM: relax conditions for allowing MSR_IA32_SPEC_CTRL accesses Date: Wed, 5 Feb 2020 16:13:48 +0100 Message-Id: <1580915628-42930-1-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.8.3.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Userspace that does not know about the AMD_IBRS bit might still allow the guest to protect itself with MSR_IA32_SPEC_CTRL using the Intel SPEC_CTRL bit. However, svm.c disallows this and will cause a #GP in the guest when writing to the MSR. Fix this by loosening the test and allowing the Intel CPUID bit, and in fact allow the AMD_STIBP bit as well since it allows writing to MSR_IA32_SPEC_CTRL too. Reported-by: Zhiyi Guo Analyzed-by: Dr. David Alan Gilbert Analyzed-by: Laszlo Ersek Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index bf0556588ad0..a3e32d61d60c 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -4225,6 +4225,8 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) break; case MSR_IA32_SPEC_CTRL: if (!msr_info->host_initiated && + !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) && + !guest_cpuid_has(vcpu, X86_FEATURE_AMD_STIBP) && !guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) && !guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD)) return 1; @@ -4310,6 +4312,8 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) break; case MSR_IA32_SPEC_CTRL: if (!msr->host_initiated && + !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) && + !guest_cpuid_has(vcpu, X86_FEATURE_AMD_STIBP) && !guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) && !guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD)) return 1; -- 1.8.3.1