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=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 77BD3C2D0C6 for ; Wed, 11 Dec 2019 15:29:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4EBF622B48 for ; Wed, 11 Dec 2019 15:29:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576078147; bh=V3c61UjcYe4scFRc07uwvsawsHuVtrB91ryO+pxN9bs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=T0Yo5xNhGIQlKRgH/FZQc3EQegzLH3DQ3SqMf4gQvwtUkDjHD/cu2jlTmgBwzVaUm bwij9HjY81dXQs9n/DM3JMW1y2prbz7MwJy4r6/KwUm8LcfbP8kezghEJUYDv+iR8K 9QvMqsEra4TWu3ampgFVYH7e9qCwNZ0xFQytynVQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387805AbfLKP3G (ORCPT ); Wed, 11 Dec 2019 10:29:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:35528 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387791AbfLKP3D (ORCPT ); Wed, 11 Dec 2019 10:29:03 -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 E79A6222C4; Wed, 11 Dec 2019 15:29:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576078142; bh=V3c61UjcYe4scFRc07uwvsawsHuVtrB91ryO+pxN9bs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zUi4a0kPU/sXMIbBPqx5ZPhAgsU+BKehomgZ8kOckr9vhAkoTgMH0R0yXO2qqBKHz uNxeryu+amonz5Y7/HClhaMvud7eGn73yp8x+Kv4/685tWG71NVlcILTMKs5BtBoyi MLTID55iJXlCalQ02BhFav68xccAb6ZEeG7hdMVI= 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 4.14 29/58] powerpc/security: Fix wrong message when RFI Flush is disable Date: Wed, 11 Dec 2019 10:28:02 -0500 Message-Id: <20191211152831.23507-29-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191211152831.23507-1-sashal@kernel.org> References: <20191211152831.23507-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 fef3f09fc238b..b3f540c9f4109 100644 --- a/arch/powerpc/kernel/security.c +++ b/arch/powerpc/kernel/security.c @@ -134,26 +134,22 @@ 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