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 36B7FC433EF for ; Wed, 9 Feb 2022 18:59:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241668AbiBIS7B (ORCPT ); Wed, 9 Feb 2022 13:59:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33918 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238908AbiBIS5g (ORCPT ); Wed, 9 Feb 2022 13:57:36 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3EA90C0401D1; Wed, 9 Feb 2022 10:57:28 -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 dfw.source.kernel.org (Postfix) with ESMTPS id CB2C661736; Wed, 9 Feb 2022 18:57:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F0412C340E7; Wed, 9 Feb 2022 18:57:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644433047; bh=a6lTLUlCPFqhaJW682/k6YpdxQGr5eC5ep3SweaQk3c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rmkDeAlqRMpoA13xSxZGfs1642qIMoweeKl6Goo6vzt9DpVFc5Y+E7W7OF5YNu2sP nepV954WisEQj86P3sUJVzrPvRHmyLJFK2M+W+iAp63P9JVxC/rhR/5SsJ/hSZNEOp G/r1nKLIR8fQT02JYlnjfOLSagJ6Kd0MLfvGTH1FzU0PE9h4HIVCoSNEVqbtH5MbPD EjRiLVQ76NxqY5WAXHFydMhldHDgqjlyoomcTCA+6yrTMjGV43rFoYwcQzghaeRctR Y9XNBbYXg2speTDKw8RzqFWZlEJgEHFWgi9JL0l3CFrsCFtVQIj9xe+qc3hGA8MjoB QxPuv7fmI1I2A== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sean Christopherson , Liam Merwick , Paolo Bonzini , Sasha Levin , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, kvm@vger.kernel.org Subject: [PATCH MANUALSEL 5.10 5/6] KVM: SVM: Don't kill SEV guest if SMAP erratum triggers in usermode Date: Wed, 9 Feb 2022 13:57:12 -0500 Message-Id: <20220209185714.48936-5-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220209185714.48936-1-sashal@kernel.org> References: <20220209185714.48936-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: kvm@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 fa543c355fbdb..d515c8e68314c 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4155,7 +4155,21 @@ static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, void *insn, int i return true; 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