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 2D8D9C00454 for ; Wed, 11 Dec 2019 15:35:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 035AD2464B for ; Wed, 11 Dec 2019 15:35:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576078543; bh=8hVghR5zDlG6MhlCqsMVwILuED2AYK/kyu11Ukhr/hk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=DHPnaDAWe6+aWtEXhxNErgNY3v0Phf1GQ/mSrdjGkJYwrUMSGUb6BuEujQqrpOnCR 31cxwnxuwUXqdA9HDjdatC7Cobv0AYikFEcJhKQf4Q+BeP79yzvhEoiY69UzJtPFO6 tddf0dtteYmX+1njQkqDpeGBEX42uG1ANJbkFM0M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388010AbfLKPfm (ORCPT ); Wed, 11 Dec 2019 10:35:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:44696 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388182AbfLKPfi (ORCPT ); Wed, 11 Dec 2019 10:35:38 -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 650D222B48; Wed, 11 Dec 2019 15:35:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576078537; bh=8hVghR5zDlG6MhlCqsMVwILuED2AYK/kyu11Ukhr/hk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KwjPSClq9WGL6zVzvCKFXdoAevcvhWtl3dLq3PgiNEj6W13bZKjka4WDT4ubUrqbq 8iDlAaqIlPyc6ym5JUnj3ZcH4NO1MSuCUv2IJ4HZp9dX7nrjQ87/vpdkeDQSI1Lvor 4CVHYQB9Z3Z4mSwhKi3A61Hab9cpBihdyu7dowBo= 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 4.9 25/42] powerpc/security: Fix wrong message when RFI Flush is disable Date: Wed, 11 Dec 2019 10:34:53 -0500 Message-Id: <20191211153510.23861-25-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191211153510.23861-1-sashal@kernel.org> References: <20191211153510.23861-1-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 db66f25c190c9..ff85fc8001836 100644 --- a/arch/powerpc/kernel/security.c +++ b/arch/powerpc/kernel/security.c @@ -135,26 +135,22 @@ 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