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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 620C2C433E3 for ; Thu, 20 Aug 2020 13:23:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3EA4322B40 for ; Thu, 20 Aug 2020 13:23:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597929823; bh=mS2r6JZi5H4zJrIi0lknmzep8tyuauI0BBhy0kH7gds=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=A/ZlENJCVIjXt04hxB7T+CJ+3Qgq8DzTuR21eZKhgTzwX6J7QlUpDjSRDlXg4VAmr kawz2u1UzqZxwFPRo6W1yx+p8kiJ7isXou1IRjn6SSemmRulwQVukQnVdy9CMk8bLC t3NS1tdkaD78pGpCzleVamwObDoHRTgPfwqVhOPY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728335AbgHTNXl (ORCPT ); Thu, 20 Aug 2020 09:23:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:46478 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728029AbgHTJeK (ORCPT ); Thu, 20 Aug 2020 05:34:10 -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 BFFA922B4E; Thu, 20 Aug 2020 09:33:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597916025; bh=mS2r6JZi5H4zJrIi0lknmzep8tyuauI0BBhy0kH7gds=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PLvK9UZg7F56OpGfLb3d6plAW+oWq4iNr4DbooagRcRTsl6ONclAuirevgdrk1hgV /+3d6A5ebKkkoLVbDLOFP6Kq5Sl3evCisdZ/Ecv4JvBPlS8fDU6ISNnXz1JibLJhgb u20IC22FxXcD832WN0DLM52PyIWRsYJ/IxKtjUw0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nelson Dsouza , Sean Christopherson , Pawan Gupta , Ingo Molnar , Tony Luck , Thomas Gleixner , Sasha Levin Subject: [PATCH 5.8 190/232] x86/bugs/multihit: Fix mitigation reporting when VMX is not in use Date: Thu, 20 Aug 2020 11:20:41 +0200 Message-Id: <20200820091621.995315719@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200820091612.692383444@linuxfoundation.org> References: <20200820091612.692383444@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Pawan Gupta [ Upstream commit f29dfa53cc8ae6ad93bae619bcc0bf45cab344f7 ] On systems that have virtualization disabled or unsupported, sysfs mitigation for X86_BUG_ITLB_MULTIHIT is reported incorrectly as: $ cat /sys/devices/system/cpu/vulnerabilities/itlb_multihit KVM: Vulnerable System is not vulnerable to DoS attack from a rogue guest when virtualization is disabled or unsupported in the hardware. Change the mitigation reporting for these cases. Fixes: b8e8c8303ff2 ("kvm: mmu: ITLB_MULTIHIT mitigation") Reported-by: Nelson Dsouza Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson Signed-off-by: Pawan Gupta Signed-off-by: Ingo Molnar Reviewed-by: Tony Luck Acked-by: Thomas Gleixner Link: https://lore.kernel.org/r/0ba029932a816179b9d14a30db38f0f11ef1f166.1594925782.git.pawan.kumar.gupta@linux.intel.com Signed-off-by: Sasha Levin --- Documentation/admin-guide/hw-vuln/multihit.rst | 4 ++++ arch/x86/kernel/cpu/bugs.c | 8 +++++++- 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/hw-vuln/multihit.rst b/Documentation/admin-guide/hw-vuln/multihit.rst index ba9988d8bce50..140e4cec38c33 100644 --- a/Documentation/admin-guide/hw-vuln/multihit.rst +++ b/Documentation/admin-guide/hw-vuln/multihit.rst @@ -80,6 +80,10 @@ The possible values in this file are: - The processor is not vulnerable. * - KVM: Mitigation: Split huge pages - Software changes mitigate this issue. + * - KVM: Mitigation: VMX unsupported + - KVM is not vulnerable because Virtual Machine Extensions (VMX) is not supported. + * - KVM: Mitigation: VMX disabled + - KVM is not vulnerable because Virtual Machine Extensions (VMX) is disabled. * - KVM: Vulnerable - The processor is vulnerable, but no mitigation enabled diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 0b71970d2d3d2..b0802d45abd30 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -31,6 +31,7 @@ #include #include #include +#include #include "cpu.h" @@ -1556,7 +1557,12 @@ static ssize_t l1tf_show_state(char *buf) static ssize_t itlb_multihit_show_state(char *buf) { - if (itlb_multihit_kvm_mitigation) + if (!boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) || + !boot_cpu_has(X86_FEATURE_VMX)) + return sprintf(buf, "KVM: Mitigation: VMX unsupported\n"); + else if (!(cr4_read_shadow() & X86_CR4_VMXE)) + return sprintf(buf, "KVM: Mitigation: VMX disabled\n"); + else if (itlb_multihit_kvm_mitigation) return sprintf(buf, "KVM: Mitigation: Split huge pages\n"); else return sprintf(buf, "KVM: Vulnerable\n"); -- 2.25.1