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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5991AC00140 for ; Fri, 5 Aug 2022 09:22:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240298AbiHEJWD (ORCPT ); Fri, 5 Aug 2022 05:22:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233773AbiHEJWB (ORCPT ); Fri, 5 Aug 2022 05:22:01 -0400 Received: from out30-131.freemail.mail.aliyun.com (out30-131.freemail.mail.aliyun.com [115.124.30.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BAF7B7390A for ; Fri, 5 Aug 2022 02:21:57 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045170;MF=liusong@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0VLQfg.m_1659691274; Received: from localhost(mailfrom:liusong@linux.alibaba.com fp:SMTPD_---0VLQfg.m_1659691274) by smtp.aliyun-inc.com; Fri, 05 Aug 2022 17:21:52 +0800 From: Liu Song To: catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] arm64: spectre: increase parameters that can be used to turn off bhb mitigation individually Date: Fri, 5 Aug 2022 17:21:14 +0800 Message-Id: <1659691274-48554-1-git-send-email-liusong@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Liu Song In our environment, it was found that the mitigation BHB has a great impact on the benchmark performance. For example, in the lmbench test, the "process fork && exit" test performance drops by 20%. So it is necessary to have the ability to turn off the mitigation individually through cmdline, thus avoiding having to compile the kernel by adjusting the config. Signed-off-by: Liu Song --- arch/arm64/kernel/proton-pack.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pack.c index 40be3a7..bd16903 100644 --- a/arch/arm64/kernel/proton-pack.c +++ b/arch/arm64/kernel/proton-pack.c @@ -988,6 +988,14 @@ static void this_cpu_set_vectors(enum arm64_bp_harden_el1_vectors slot) isb(); } +static bool __read_mostly __nospectre_bhb; +static int __init parse_spectre_bhb_param(char *str) +{ + __nospectre_bhb = true; + return 0; +} +early_param("nospectre_bhb", parse_spectre_bhb_param); + void spectre_bhb_enable_mitigation(const struct arm64_cpu_capabilities *entry) { bp_hardening_cb_t cpu_cb; @@ -1001,7 +1009,7 @@ void spectre_bhb_enable_mitigation(const struct arm64_cpu_capabilities *entry) /* No point mitigating Spectre-BHB alone. */ } else if (!IS_ENABLED(CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY)) { pr_info_once("spectre-bhb mitigation disabled by compile time option\n"); - } else if (cpu_mitigations_off()) { + } else if (cpu_mitigations_off() || __nospectre_bhb) { pr_info_once("spectre-bhb mitigation disabled by command line option\n"); } else if (supports_ecbhb(SCOPE_LOCAL_CPU)) { state = SPECTRE_MITIGATED; -- 1.8.3.1