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=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,T_DKIMWL_WL_HIGH,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 79D88C43219 for ; Thu, 2 May 2019 15:34:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4B065214DA for ; Thu, 2 May 2019 15:34:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556811275; bh=Na7835Vjg79k31aUQRQ3eZo3Y9Jd6T+CHPZgrq81pmA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=vCOsgKlnH+nGsULagbxdCh3gaDiYgMkpp0SPjoca6+zeCaIdGbgczg9vgxQF78Unw haRVqWgcNC8y7UvU5lIQDkIHvYoYgwWWnxJ1/sGHNx+tMtLKGPp3s7r7bkOyv0Q600 KxcP8YuDKATrF1N+WMmJ0qw34QD/5113GPB/gDH4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728542AbfEBPee (ORCPT ); Thu, 2 May 2019 11:34:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:51480 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729086AbfEBPcC (ORCPT ); Thu, 2 May 2019 11:32:02 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D39CA20C01; Thu, 2 May 2019 15:32:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556811121; bh=Na7835Vjg79k31aUQRQ3eZo3Y9Jd6T+CHPZgrq81pmA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1iYidboAO5X5t8xrH6zk+Ukd4ZxOvK/7p+CE1biX+f5vki/vz3ie0PzvHgjXGpOEY cJQ9fCHqkUZ81zNNob7zS9QCKCS+hWoEelloU4qV+RP36sjeTk196TGmzVsMXK79qm OaZRyu/nxbNsfrkgOJnV1exrroy2s40ADkkgAka0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Venkatesh Srinivas , Jim Mattson , Tom Lendacky , Borislav Petkov , Joerg Roedel , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Paolo Bonzini , Brijesh Singh , "Sasha Levin (Microsoft)" Subject: [PATCH 5.0 083/101] KVM: SVM: Workaround errata#1096 (insn_len maybe zero on SMAP violation) Date: Thu, 2 May 2019 17:21:25 +0200 Message-Id: <20190502143345.428568863@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190502143339.434882399@linuxfoundation.org> References: <20190502143339.434882399@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit 05d5a48635259e621ea26d01e8316c6feeb34190 ] Errata#1096: On a nested data page fault when CR.SMAP=1 and the guest data read generates a SMAP violation, GuestInstrBytes field of the VMCB on a VMEXIT will incorrectly return 0h instead the correct guest instruction bytes . Recommend Workaround: To determine what instruction the guest was executing the hypervisor will have to decode the instruction at the instruction pointer. The recommended workaround can not be implemented for the SEV guest because guest memory is encrypted with the guest specific key, and instruction decoder will not be able to decode the instruction bytes. If we hit this errata in the SEV guest then log the message and request a guest shutdown. Reported-by: Venkatesh Srinivas Cc: Jim Mattson Cc: Tom Lendacky Cc: Borislav Petkov Cc: Joerg Roedel Cc: "Radim Krčmář" Cc: Paolo Bonzini Signed-off-by: Brijesh Singh Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin (Microsoft) --- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/mmu.c | 8 +++++--- arch/x86/kvm/svm.c | 32 ++++++++++++++++++++++++++++++++ arch/x86/kvm/vmx/vmx.c | 6 ++++++ 4 files changed, 45 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 71d763ad2637..9f2d890733a9 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1198,6 +1198,8 @@ struct kvm_x86_ops { int (*nested_enable_evmcs)(struct kvm_vcpu *vcpu, uint16_t *vmcs_version); uint16_t (*nested_get_evmcs_version)(struct kvm_vcpu *vcpu); + + bool (*need_emulation_on_page_fault)(struct kvm_vcpu *vcpu); }; struct kvm_arch_async_pf { diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index acab95dcffb6..77dbb57412cc 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -5395,10 +5395,12 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u64 error_code, * This can happen if a guest gets a page-fault on data access but the HW * table walker is not able to read the instruction page (e.g instruction * page is not present in memory). In those cases we simply restart the - * guest. + * guest, with the exception of AMD Erratum 1096 which is unrecoverable. */ - if (unlikely(insn && !insn_len)) - return 1; + if (unlikely(insn && !insn_len)) { + if (!kvm_x86_ops->need_emulation_on_page_fault(vcpu)) + return 1; + } er = x86_emulate_instruction(vcpu, cr2, emulation_type, insn, insn_len); diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 516c1de03d47..e544cec812f9 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -7114,6 +7114,36 @@ static int nested_enable_evmcs(struct kvm_vcpu *vcpu, return -ENODEV; } +static bool svm_need_emulation_on_page_fault(struct kvm_vcpu *vcpu) +{ + bool is_user, smap; + + is_user = svm_get_cpl(vcpu) == 3; + smap = !kvm_read_cr4_bits(vcpu, X86_CR4_SMAP); + + /* + * Detect and workaround Errata 1096 Fam_17h_00_0Fh + * + * In non SEV guest, hypervisor will be able to read the guest + * memory to decode the instruction pointer when insn_len is zero + * so we return true to indicate that decoding is possible. + * + * But in the SEV guest, the guest memory is encrypted with the + * guest specific key and hypervisor will not be able to decode the + * instruction pointer so we will not able to workaround it. Lets + * print the error and request to kill the guest. + */ + if (is_user && smap) { + if (!sev_guest(vcpu->kvm)) + return true; + + pr_err_ratelimited("KVM: Guest triggered AMD Erratum 1096\n"); + kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu); + } + + return false; +} + static struct kvm_x86_ops svm_x86_ops __ro_after_init = { .cpu_has_kvm_support = has_svm, .disabled_by_bios = is_disabled, @@ -7247,6 +7277,8 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = { .nested_enable_evmcs = nested_enable_evmcs, .nested_get_evmcs_version = nested_get_evmcs_version, + + .need_emulation_on_page_fault = svm_need_emulation_on_page_fault, }; static int __init svm_init(void) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 34499081022c..e7fe8c692362 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7526,6 +7526,11 @@ static int enable_smi_window(struct kvm_vcpu *vcpu) return 0; } +static bool vmx_need_emulation_on_page_fault(struct kvm_vcpu *vcpu) +{ + return 0; +} + static __init int hardware_setup(void) { unsigned long host_bndcfgs; @@ -7828,6 +7833,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = { .set_nested_state = NULL, .get_vmcs12_pages = NULL, .nested_enable_evmcs = NULL, + .need_emulation_on_page_fault = vmx_need_emulation_on_page_fault, }; static void vmx_cleanup_l1d_flush(void) -- 2.19.1