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=-9.8 required=3.0 tests=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=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 00AB8C3276C for ; Thu, 2 Jan 2020 22:59:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CB48920866 for ; Thu, 2 Jan 2020 22:59:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578005995; bh=FfGRDsOa077Vrq/0aEEXxJBym2aW9dkpdNIfmIGUXtg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Ehcs3C0/d3Z0bJ6l/NFxE2bfyn5N8t3TNLPxIPCGwuwiMQbD69SUHcRZ7/fL7z1db WIBmmo9ndm8EH92vM3cJlKDeaMcOHxwcslDwkUpgBpat5WeXPLnwMW1Tw3Kniw5aHz hSFz5c3PRGMtNVUqsH63TIpkxJdBhfNGuasi6Hhw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727734AbgABWNj (ORCPT ); Thu, 2 Jan 2020 17:13:39 -0500 Received: from mail.kernel.org ([198.145.29.99]:53572 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727428AbgABWNi (ORCPT ); Thu, 2 Jan 2020 17:13:38 -0500 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 8CC7521D7D; Thu, 2 Jan 2020 22:13:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578003218; bh=FfGRDsOa077Vrq/0aEEXxJBym2aW9dkpdNIfmIGUXtg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dChddzFOzPe5sJFL6YqiTK0BdIm6xLOS7h95vcAoUGSvbLV/M5rmTMYmwdSvsdVoY 12Nw6itxlacOoh9PUh2OfOoDThamdawXp1rIt3iBd3d55bvGz4PPyi//xpGqyGKSyF xRv0qfjYvqeOX1NOpapnmsAkIoseeBOMg2OGi6vU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Gustavo L. F. Walbon" , "Mauro S. M. Rodrigues" , Michael Ellerman , Sasha Levin Subject: [PATCH 5.4 069/191] powerpc/security: Fix wrong message when RFI Flush is disable Date: Thu, 2 Jan 2020 23:05:51 +0100 Message-Id: <20200102215837.338429804@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200102215829.911231638@linuxfoundation.org> References: <20200102215829.911231638@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: Gustavo L. F. Walbon [ Upstream commit 4e706af3cd8e1d0503c25332b30cad33c97ed442 ] The issue was showing "Mitigation" message via sysfs whatever the state of "RFI Flush", but it should show "Vulnerable" when it is disabled. If you have "L1D private" feature enabled and not "RFI Flush" you are vulnerable to meltdown attacks. "RFI Flush" is the key feature to mitigate the meltdown whatever the "L1D private" state. SEC_FTR_L1D_THREAD_PRIV is a feature for Power9 only. So the message should be as the truth table shows: CPU | L1D private | RFI Flush | sysfs ----|-------------|-----------|------------------------------------- P9 | False | False | Vulnerable P9 | False | True | Mitigation: RFI Flush P9 | True | False | Vulnerable: L1D private per thread P9 | True | True | Mitigation: RFI Flush, L1D private per thread P8 | False | False | Vulnerable P8 | False | True | Mitigation: RFI Flush Output before this fix: # cat /sys/devices/system/cpu/vulnerabilities/meltdown Mitigation: RFI Flush, L1D private per thread # echo 0 > /sys/kernel/debug/powerpc/rfi_flush # cat /sys/devices/system/cpu/vulnerabilities/meltdown Mitigation: L1D private per thread Output after fix: # cat /sys/devices/system/cpu/vulnerabilities/meltdown Mitigation: RFI Flush, L1D private per thread # echo 0 > /sys/kernel/debug/powerpc/rfi_flush # cat /sys/devices/system/cpu/vulnerabilities/meltdown Vulnerable: L1D private per thread Signed-off-by: Gustavo L. F. Walbon Signed-off-by: Mauro S. M. Rodrigues Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190502210907.42375-1-gwalbon@linux.ibm.com Signed-off-by: Sasha Levin --- arch/powerpc/kernel/security.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c index 298a2e3ad6f4..d341b464f23c 100644 --- a/arch/powerpc/kernel/security.c +++ b/arch/powerpc/kernel/security.c @@ -142,26 +142,22 @@ ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, cha thread_priv = security_ftr_enabled(SEC_FTR_L1D_THREAD_PRIV); - if (rfi_flush || thread_priv) { + if (rfi_flush) { struct seq_buf s; seq_buf_init(&s, buf, PAGE_SIZE - 1); - seq_buf_printf(&s, "Mitigation: "); - - if (rfi_flush) - seq_buf_printf(&s, "RFI Flush"); - - if (rfi_flush && thread_priv) - seq_buf_printf(&s, ", "); - + seq_buf_printf(&s, "Mitigation: RFI Flush"); if (thread_priv) - seq_buf_printf(&s, "L1D private per thread"); + seq_buf_printf(&s, ", L1D private per thread"); seq_buf_printf(&s, "\n"); return s.len; } + if (thread_priv) + return sprintf(buf, "Vulnerable: L1D private per thread\n"); + if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) && !security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR)) return sprintf(buf, "Not affected\n"); -- 2.20.1