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=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 2611BC4338F for ; Mon, 16 Aug 2021 14:01:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 049C760F5C for ; Mon, 16 Aug 2021 14:01:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237074AbhHPOC2 (ORCPT ); Mon, 16 Aug 2021 10:02:28 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:56250 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231424AbhHPN66 (ORCPT ); Mon, 16 Aug 2021 09:58:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629122257; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=86AjNMQBBI/biMMBre0wJEFayw5cohkZhTxP/vuqbGY=; b=O8axeF+QRx13KAf6bBNV9n/cEkEeynGcjZquzab6Drg0m/7b0Q6ZLomNix7MQVg+4I+U/X gqJ8ZAVg1d9yQtiN8DtuvEHj+itl+nflOi795Y2HMS8ENeOPdYVqrhcxSr6A2OMxpRoeBj 0lZgQpwwFxcDorVexeim8kaqUuNUrWk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-430-bQJOFIbOOeWklPz6X80c1g-1; Mon, 16 Aug 2021 09:57:34 -0400 X-MC-Unique: bQJOFIbOOeWklPz6X80c1g-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E4EDD18C9F53; Mon, 16 Aug 2021 13:57:33 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8533560939; Mon, 16 Aug 2021 13:57:33 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: seanjc@google.com, Maxim Levitsky Subject: [FYI PATCH] KVM: nSVM: always intercept VMLOAD/VMSAVE when nested (CVE-2021-3656) Date: Mon, 16 Aug 2021 09:57:32 -0400 Message-Id: <20210816135732.3836586-2-pbonzini@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Maxim Levitsky If L1 disables VMLOAD/VMSAVE intercepts, and doesn't enable Virtual VMLOAD/VMSAVE (currently not supported for the nested hypervisor), then VMLOAD/VMSAVE must operate on the L1 physical memory, which is only possible by making L0 intercept these instructions. Failure to do so allowed the nested guest to run VMLOAD/VMSAVE unintercepted, and thus read/write portions of the host physical memory. Fixes: 89c8a4984fc9 ("KVM: SVM: Enable Virtual VMLOAD VMSAVE feature") Suggested-by: Paolo Bonzini Signed-off-by: Maxim Levitsky Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/nested.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 28381ca5221c..e5515477c30a 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -158,6 +158,9 @@ void recalc_intercepts(struct vcpu_svm *svm) /* If SMI is not intercepted, ignore guest SMI intercept as well */ if (!intercept_smi) vmcb_clr_intercept(c, INTERCEPT_SMI); + + vmcb_set_intercept(c, INTERCEPT_VMLOAD); + vmcb_set_intercept(c, INTERCEPT_VMSAVE); } static void copy_vmcb_control_area(struct vmcb_control_area *dst, -- 2.27.0