From patchwork Tue Jan 5 09:28:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 357438 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, 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 26E22C43381 for ; Tue, 5 Jan 2021 09:30:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E688C229C4 for ; Tue, 5 Jan 2021 09:30:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728462AbhAEJaY (ORCPT ); Tue, 5 Jan 2021 04:30:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:49752 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728448AbhAEJaD (ORCPT ); Tue, 5 Jan 2021 04:30:03 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8EADC22AAB; Tue, 5 Jan 2021 09:28:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609838932; bh=dasKtHTCYIrQxpY8qIuQBndCSh8AFrxZODHylccCWf8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZKr5jlB2vUmedy7agUazf+pS1pwkn8YYwL2DSdH1awqJ3kLgnOxtIHoE0UcCZhDdU gkpTNwxUx/mcU3SMYZ9coGcjO1iSVOPpyfsyN084kT5d+d2yROklsyg8+VjLr3mGO8 zQFQgL6mcJ/LRKdyCQ33f9fN1DLBp8K17rl5VrXs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zhiyi Guo , Paolo Bonzini , Sasha Levin , "Dr . David Alan Gilbert" , Laszlo Ersek Subject: [PATCH 4.19 09/29] KVM: SVM: relax conditions for allowing MSR_IA32_SPEC_CTRL accesses Date: Tue, 5 Jan 2021 10:28:55 +0100 Message-Id: <20210105090819.728680989@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210105090818.518271884@linuxfoundation.org> References: <20210105090818.518271884@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Paolo Bonzini [ Upstream commit df7e8818926eb4712b67421442acf7d568fe2645 ] 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 Signed-off-by: Sasha Levin --- 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 a0c3d1b4b295b..f513110983d4c 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -4209,6 +4209,8 @@ 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; @@ -4312,6 +4314,8 @@ 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;