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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 C6115C43603 for ; Wed, 11 Dec 2019 16:03:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9770920836 for ; Wed, 11 Dec 2019 16:03:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576080181; bh=MI+upR3XDZvlOTtT7sFyy/EllEDFl2ez+59ZAJWaTnI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=qtvAZczybqiSMfQLrFxJwz712fsHgjY81HCi5cB5KA3caDR6aP1XFLNalXJ09L6h/ 9Tf2Du8yVatTWbVuPoYWPqbZBtBfkKJO8xCoO03ELyx46nyaPgwC3tlV1Ukp7NnsX0 En60yx03z5fwICp5hnWPALjoTZ1M/KoaeWELKKTI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731343AbfLKQDA (ORCPT ); Wed, 11 Dec 2019 11:03:00 -0500 Received: from mail.kernel.org ([198.145.29.99]:35966 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731333AbfLKPNG (ORCPT ); Wed, 11 Dec 2019 10:13:06 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id F037524680; Wed, 11 Dec 2019 15:13:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576077185; bh=MI+upR3XDZvlOTtT7sFyy/EllEDFl2ez+59ZAJWaTnI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TW9Pmb1YuWLVkCqXOPDf1iRS23RA+/M4C1xQ5C52rNqARhSa8kiL3NVwFv/dg+xpU Q7vGub7jMLQxP08XUEOjvYoz0fQS6TTW0WpomXSzI2vNmezWYZ5zgs5fn0p/KHTF2K Byy1lplrz8vtEZLmbT47uLMx0FBLaX1n1w2FvEtI= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Gustavo L. F. Walbon" , "Mauro S . M . Rodrigues" , Michael Ellerman , Sasha Levin , linuxppc-dev@lists.ozlabs.org Subject: [PATCH AUTOSEL 5.4 069/134] powerpc/security: Fix wrong message when RFI Flush is disable Date: Wed, 11 Dec 2019 10:10:45 -0500 Message-Id: <20191211151150.19073-69-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191211151150.19073-1-sashal@kernel.org> References: <20191211151150.19073-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 298a2e3ad6f4c..d341b464f23c6 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