From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 550122F478A; Mon, 5 May 2025 23:15:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746486951; cv=none; b=iz3eqxYiidhTJ1Ycw5rNC46l7nInUC4rnVFPG3rLi9f3mwv9dpyCpmLhI/SJE9NINSmH71/g68HifuFBXEi9+sMn8R+JzTEijKZ6h+nJ2zdHtU9qd7EVtuVjZz0CbjTkMo1jytvLieKVGIoNZz/CjsYpKkelXPt0q5jGoijxncg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746486951; c=relaxed/simple; bh=pHKueES8/Xf6oiD7xIjwXZCnandN1qb9OpE6s5N8vrA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=C8CkLdheLBJRgkdeLMCrNC375/5+i2DKDWybKlRu9ieAmuwR20aCZ0RaAXNLaowP2HAy2LSatVr1NqVn/fQrYo9obcWUE01WB0Ooj+fARD6IYmeK/BQUBigR8TZi2sE/+vFx9yOjRxUxgf/Be9OJNtZqduYjW/PYhGhXymN0iIk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mlHnt2cB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mlHnt2cB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02CF0C4CEED; Mon, 5 May 2025 23:15:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746486950; bh=pHKueES8/Xf6oiD7xIjwXZCnandN1qb9OpE6s5N8vrA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mlHnt2cBKBrFHYwjqKgwKbXBDKFGRcY0fi9lrDn7mij4ZNwQ/qR0hrh6j4526rAcu bNtMb6esmZ4R0cdod4bpohqWRy6YA+dWmoSQkck4IAe9jni2XJ3w+3Koa7L2lanXvQ q/TrnN1nYyxMMq7mVQDXooVz9zBgL1N7QwZHa9PmoK3ZD8Lp1+KTdqx+23X+Zqjws4 CYeZ1moSKX23DyHaVtLXm9nGlcT63CI52mkg2gjyc3m0mcVz45QCS0pydVGzSBjHqY Elcnvq+jBsrtFi2IIaF80HC4fgHIG1oCxpbptfjDPggzGjJMWA/mke2mHlkCwo3tqw wgBAVqRPzzuuQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Breno Leitao , Ingo Molnar , Pawan Gupta , Josh Poimboeuf , Peter Zijlstra , David Kaplan , Sasha Levin , corbet@lwn.net, tglx@linutronix.de, bp@alien8.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, akpm@linux-foundation.org, paulmck@kernel.org, rostedt@goodmis.org, thuth@redhat.com, ardb@kernel.org, gregkh@linuxfoundation.org, linux-doc@vger.kernel.org Subject: [PATCH AUTOSEL 5.15 074/153] x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2 Date: Mon, 5 May 2025 19:12:01 -0400 Message-Id: <20250505231320.2695319-74-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250505231320.2695319-1-sashal@kernel.org> References: <20250505231320.2695319-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.15.181 Content-Transfer-Encoding: 8bit From: Breno Leitao [ Upstream commit 98fdaeb296f51ef08e727a7cc72e5b5c864c4f4d ] Change the default value of spectre v2 in user mode to respect the CONFIG_MITIGATION_SPECTRE_V2 config option. Currently, user mode spectre v2 is set to auto (SPECTRE_V2_USER_CMD_AUTO) by default, even if CONFIG_MITIGATION_SPECTRE_V2 is disabled. Set the spectre_v2 value to auto (SPECTRE_V2_USER_CMD_AUTO) if the Spectre v2 config (CONFIG_MITIGATION_SPECTRE_V2) is enabled, otherwise set the value to none (SPECTRE_V2_USER_CMD_NONE). Important to say the command line argument "spectre_v2_user" overwrites the default value in both cases. When CONFIG_MITIGATION_SPECTRE_V2 is not set, users have the flexibility to opt-in for specific mitigations independently. In this scenario, setting spectre_v2= will not enable spectre_v2_user=, and command line options spectre_v2_user and spectre_v2 are independent when CONFIG_MITIGATION_SPECTRE_V2=n. Signed-off-by: Breno Leitao Signed-off-by: Ingo Molnar Reviewed-by: Pawan Gupta Acked-by: Josh Poimboeuf Cc: Peter Zijlstra Cc: David Kaplan Link: https://lore.kernel.org/r/20241031-x86_bugs_last_v2-v2-2-b7ff1dab840e@debian.org Signed-off-by: Sasha Levin --- Documentation/admin-guide/kernel-parameters.txt | 2 ++ arch/x86/kernel/cpu/bugs.c | 10 +++++++--- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index ede522c60ac4f..0bbe79287596d 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5430,6 +5430,8 @@ Selecting 'on' will also enable the mitigation against user space to user space task attacks. + Selecting specific mitigation does not force enable + user mitigations. Selecting 'off' will disable both the kernel and the user space protections. diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 75cd45f2338dc..f47590a9f6896 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1262,9 +1262,13 @@ static __ro_after_init enum spectre_v2_mitigation_cmd spectre_v2_cmd; static enum spectre_v2_user_cmd __init spectre_v2_parse_user_cmdline(void) { + enum spectre_v2_user_cmd mode; char arg[20]; int ret, i; + mode = IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? + SPECTRE_V2_USER_CMD_AUTO : SPECTRE_V2_USER_CMD_NONE; + switch (spectre_v2_cmd) { case SPECTRE_V2_CMD_NONE: return SPECTRE_V2_USER_CMD_NONE; @@ -1277,7 +1281,7 @@ spectre_v2_parse_user_cmdline(void) ret = cmdline_find_option(boot_command_line, "spectre_v2_user", arg, sizeof(arg)); if (ret < 0) - return SPECTRE_V2_USER_CMD_AUTO; + return mode; for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) { if (match_option(arg, ret, v2_user_options[i].option)) { @@ -1287,8 +1291,8 @@ spectre_v2_parse_user_cmdline(void) } } - pr_err("Unknown user space protection option (%s). Switching to AUTO select\n", arg); - return SPECTRE_V2_USER_CMD_AUTO; + pr_err("Unknown user space protection option (%s). Switching to default\n", arg); + return mode; } static inline bool spectre_v2_in_eibrs_mode(enum spectre_v2_mitigation mode) -- 2.39.5