From patchwork Mon Jul 15 20:30:42 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liran Alon X-Patchwork-Id: 11044977 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 11715746 for ; Mon, 15 Jul 2019 20:31:19 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F22CB28477 for ; Mon, 15 Jul 2019 20:31:18 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DD9872848B; Mon, 15 Jul 2019 20:31:18 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7A67528477 for ; Mon, 15 Jul 2019 20:31:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731677AbfGOUbR (ORCPT ); Mon, 15 Jul 2019 16:31:17 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:51620 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731366AbfGOUbR (ORCPT ); Mon, 15 Jul 2019 16:31:17 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x6FKSpbG074899; Mon, 15 Jul 2019 20:31:04 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=corp-2018-07-02; bh=EYTrKg8RF1oUflTqZCBg9xy7h3/ijviGoYM08L3E+Oo=; b=z5U0C4yvzpDn3Z1w2H/dO7YnK4cP6yi25Crfvz6/oGN4itVAPmYrNAtjCZQJL2VLLAfq 7LuSKCacY9e+UP12i/n1OUilAIdmdskW3YIFzlQi1rzYObw6w+0s12tvLyaqjBz3vQfT TTyo2qBDOAb8JYbOjP03PAd8e7/Jsra3+nQCKdTlkipZQR8JXGUWpPnbGRVOcgdMprYd nRqHwexGaynFoNi9wi/sPOXaWGb8xGVe9zLPTM9z421K4JRejfTMMzF7thBHjeRym5Lp bf0fOmBMlrIILKeNtnP1kBLOKYApBP7qusxf3+g5YrXhu7IXg4Gh7mYjGfQJ4uezfWIr sw== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by userp2120.oracle.com with ESMTP id 2tq7xqrp6m-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 15 Jul 2019 20:31:04 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x6FKRmsO128616; Mon, 15 Jul 2019 20:31:04 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userp3030.oracle.com with ESMTP id 2tq4dth59c-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 15 Jul 2019 20:31:04 +0000 Received: from abhmp0014.oracle.com (abhmp0014.oracle.com [141.146.116.20]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x6FKV36X020971; Mon, 15 Jul 2019 20:31:03 GMT Received: from spark.ravello.local (/213.57.127.2) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 15 Jul 2019 13:31:03 -0700 From: Liran Alon To: pbonzini@redhat.com, rkrcmar@redhat.com, kvm@vger.kernel.org Cc: brijesh.singh@amd.com, Liran Alon , Boris Ostrovsky Subject: [PATCH 1/2] KVM: SVM: Fix workaround for AMD Errata 1096 Date: Mon, 15 Jul 2019 23:30:42 +0300 Message-Id: <20190715203043.100483-2-liran.alon@oracle.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190715203043.100483-1-liran.alon@oracle.com> References: <20190715203043.100483-1-liran.alon@oracle.com> MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9319 signatures=668688 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=915 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907150234 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9319 signatures=668688 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=957 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907150234 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP According to AMD Errata 1096: "On a nested data page fault when CR4.SMAP = 1 and the guest data read generates a SMAP violation, the GuestInstrBytes field of the VMCB on a VMEXIT will incorrectly return 0h instead the correct guest instruction bytes." As stated above, errata is encountered when guest read generates a SMAP violation. i.e. vCPU runs with CPL<3 and CR4.SMAP=1. However, code have mistakenly checked if CPL==3 and CR4.SMAP==0. To avoid future confusion and improve code readbility, comment errata details in code and not just in commit message. Fixes: 05d5a4863525 ("KVM: SVM: Workaround errata#1096 (insn_len maybe zero on SMAP violation)") Reviewed-by: Boris Ostrovsky Signed-off-by: Liran Alon --- arch/x86/kvm/svm.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 735b8c01895e..79023a41f7a7 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -7123,10 +7123,19 @@ 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); + smap = kvm_read_cr4_bits(vcpu, X86_CR4_SMAP); /* - * Detect and workaround Errata 1096 Fam_17h_00_0Fh + * Detect and workaround Errata 1096 Fam_17h_00_0Fh. + * + * Errata: + * On a nested page fault when CR4.SMAP=1 and the guest data read generates + * a SMAP violation, GuestIntrBytes field of the VMCB on a VMEXIT will + * incorrectly return 0 instead the correct guest instruction bytes. + * + * Workaround: + * To determine what instruction the guest was executing, the hypervisor + * will have to decode the instruction at the instruction pointer. * * In non SEV guest, hypervisor will be able to read the guest * memory to decode the instruction pointer when insn_len is zero @@ -7137,11 +7146,11 @@ static bool svm_need_emulation_on_page_fault(struct kvm_vcpu *vcpu) * 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 (!is_user && smap) { if (!sev_guest(vcpu->kvm)) return true; - pr_err_ratelimited("KVM: Guest triggered AMD Erratum 1096\n"); + pr_err_ratelimited("KVM: SEV Guest triggered AMD Erratum 1096\n"); kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu); }