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=-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 59AC9C4332D for ; Mon, 4 Jan 2021 16:00:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 00C9822473 for ; Mon, 4 Jan 2021 16:00:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728243AbhADQAK (ORCPT ); Mon, 4 Jan 2021 11:00:10 -0500 Received: from mail.kernel.org ([198.145.29.99]:36552 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727434AbhADQAB (ORCPT ); Mon, 4 Jan 2021 11:00:01 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 073D0224DE; Mon, 4 Jan 2021 15:59:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609775970; bh=ayMLEWLTO3ln5gCVi+N7vwffY2GRGQLWDRhp7COPZvE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CaplG1qk1so6dHIrpuyqPz6MKaPJZdq4x+pN76cyWbhK5MbB0GNY1qOmgbZa8Eo7u fMW4cZYlM5cM7DjQUJqRzoWJ1SRBeVktlej7A5FS+/borNEhTareNUrEzITu7/mr3x tbH0TVIIihLCMFm5ky0Fn8q0cwiQH61Z581tvl3A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jim Mattson , Paolo Bonzini , Sasha Levin Subject: [PATCH 5.4 12/47] KVM: x86: avoid incorrect writes to host MSR_IA32_SPEC_CTRL Date: Mon, 4 Jan 2021 16:57:11 +0100 Message-Id: <20210104155706.339275609@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210104155705.740576914@linuxfoundation.org> References: <20210104155705.740576914@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paolo Bonzini [ Upstream commit 6441fa6178f5456d1d4b512c08798888f99db185 ] If the guest is configured to have SPEC_CTRL but the host does not (which is a nonsensical configuration but these are not explicitly forbidden) then a host-initiated MSR write can write vmx->spec_ctrl (respectively svm->spec_ctrl) and trigger a #GP when KVM tries to restore the host value of the MSR. Add a more comprehensive check for valid bits of SPEC_CTRL, covering host CPUID flags and, since we are at it and it is more correct that way, guest CPUID flags too. For AMD, remove the unnecessary is_guest_mode check around setting the MSR interception bitmap, so that the code looks the same as for Intel. Cc: Jim Mattson Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- arch/x86/kvm/svm.c | 9 +++------ arch/x86/kvm/vmx/vmx.c | 7 +++---- arch/x86/kvm/x86.c | 22 ++++++++++++++++++++++ arch/x86/kvm/x86.h | 1 + 4 files changed, 29 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index c79c1a07f44b9..72bf1d8175ac2 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -4322,12 +4322,10 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) !guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD)) return 1; - /* The STIBP bit doesn't fault even if it's not advertised */ - if (data & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP | SPEC_CTRL_SSBD)) + if (data & ~kvm_spec_ctrl_valid_bits(vcpu)) return 1; svm->spec_ctrl = data; - if (!data) break; @@ -4351,13 +4349,12 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) if (data & ~PRED_CMD_IBPB) return 1; - + if (!boot_cpu_has(X86_FEATURE_AMD_IBPB)) + return 1; if (!data) break; wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB); - if (is_guest_mode(vcpu)) - break; set_msr_interception(svm->msrpm, MSR_IA32_PRED_CMD, 0, 1); break; case MSR_AMD64_VIRT_SPEC_CTRL: diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 2a1ed3aae100e..8450fce70bd96 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1974,12 +1974,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL)) return 1; - /* The STIBP bit doesn't fault even if it's not advertised */ - if (data & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP | SPEC_CTRL_SSBD)) + if (data & ~kvm_spec_ctrl_valid_bits(vcpu)) return 1; vmx->spec_ctrl = data; - if (!data) break; @@ -2006,7 +2004,8 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) if (data & ~PRED_CMD_IBPB) return 1; - + if (!boot_cpu_has(X86_FEATURE_SPEC_CTRL)) + return 1; if (!data) break; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b7f86acb8c911..72990c3c6faf7 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10369,6 +10369,28 @@ bool kvm_arch_no_poll(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(kvm_arch_no_poll); +u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu) +{ + uint64_t bits = SPEC_CTRL_IBRS | SPEC_CTRL_STIBP | SPEC_CTRL_SSBD; + + /* The STIBP bit doesn't fault even if it's not advertised */ + if (!guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) && + !guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS)) + bits &= ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP); + if (!boot_cpu_has(X86_FEATURE_SPEC_CTRL) && + !boot_cpu_has(X86_FEATURE_AMD_IBRS)) + bits &= ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP); + + if (!guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL_SSBD) && + !guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD)) + bits &= ~SPEC_CTRL_SSBD; + if (!boot_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) && + !boot_cpu_has(X86_FEATURE_AMD_SSBD)) + bits &= ~SPEC_CTRL_SSBD; + + return bits; +} +EXPORT_SYMBOL_GPL(kvm_spec_ctrl_valid_bits); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio); diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index de6b55484876a..301286d924320 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -368,5 +368,6 @@ static inline bool kvm_pat_valid(u64 data) void kvm_load_guest_xcr0(struct kvm_vcpu *vcpu); void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu); +u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu); #endif -- 2.27.0