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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 26D1AC43217 for ; Mon, 14 Feb 2022 10:27:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346637AbiBNK1r (ORCPT ); Mon, 14 Feb 2022 05:27:47 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:33428 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344320AbiBNKZU (ORCPT ); Mon, 14 Feb 2022 05:25:20 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0D8186E4F9; Mon, 14 Feb 2022 01:56:59 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id B8C03B80DC4; Mon, 14 Feb 2022 09:56:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3959C340E9; Mon, 14 Feb 2022 09:56:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1644832616; bh=x2jfxv6PFGtgRCW1G1/ZajYjEIi5Ja02neps3iJgefE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a4ivL9/UlfuArpmYodNUw9T32SbX0MeE+Ks1AFtP+oBGwOaqbwJutavaPyue0nQxB GZfXMhGd93QG4fqyGiC2CWxEVTHmmfEOxhmthmRC61MeW2+5Xb9isToGY5GuBsDDEG ixAVjbAqnU68PE/83Ls5nZkk9r6NB3iG/0m6mDQ4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Christopherson , Liam Merwick , Paolo Bonzini , Sasha Levin Subject: [PATCH 5.16 070/203] KVM: SVM: Dont kill SEV guest if SMAP erratum triggers in usermode Date: Mon, 14 Feb 2022 10:25:14 +0100 Message-Id: <20220214092512.653838993@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220214092510.221474733@linuxfoundation.org> References: <20220214092510.221474733@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: Sean Christopherson [ Upstream commit cdf85e0c5dc766fc7fc779466280e454a6d04f87 ] Inject a #GP instead of synthesizing triple fault to try to avoid killing the guest if emulation of an SEV guest fails due to encountering the SMAP erratum. The injected #GP may still be fatal to the guest, e.g. if the userspace process is providing critical functionality, but KVM should make every attempt to keep the guest alive. Signed-off-by: Sean Christopherson Reviewed-by: Liam Merwick Message-Id: <20220120010719.711476-10-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- arch/x86/kvm/svm/svm.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 3efada37272c0..d6a4acaa65742 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4530,7 +4530,21 @@ static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, void *insn, int i is_user = svm_get_cpl(vcpu) == 3; if (smap && (!smep || is_user)) { pr_err_ratelimited("KVM: SEV Guest triggered AMD Erratum 1096\n"); - kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu); + + /* + * If the fault occurred in userspace, arbitrarily inject #GP + * to avoid killing the guest and to hopefully avoid confusing + * the guest kernel too much, e.g. injecting #PF would not be + * coherent with respect to the guest's page tables. Request + * triple fault if the fault occurred in the kernel as there's + * no fault that KVM can inject without confusing the guest. + * In practice, the triple fault is moot as no sane SEV kernel + * will execute from user memory while also running with SMAP=1. + */ + if (is_user) + kvm_inject_gp(vcpu, 0); + else + kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu); } return false; -- 2.34.1