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 07D9D3792B4; Mon, 5 May 2025 23:00:58 +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=1746486060; cv=none; b=fWMzePRT2NYDhLxhBVj9CmiJQMzEivZdLPxeqS6nkKCYu+HcdgR7WMz1F5dBec91SGPQmx6MWGxbk+zvCATZbnozhXRl/ZEq5PSYOaeAgsedOovuMPnynXKuKfFCT1TabHZEYdG+15SB/aUhBIuSlqSqbUgIPjWmWVJUmD8fORY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746486060; c=relaxed/simple; bh=BLHcE08rHIsKAZb0PIIR3MMag85ICV+AGfZz6R+LiXU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=UonqKQDM5KhaffYmqsnsz/cDHLthBGaQM9dIPcORx78kZWZW6LuZ2dXff36I3q92FBsBWkabIod3lPmOtF2Lt0nJNkrapoQBmO9mTkxZvWn5ywZ96YuL8JD/2o1WPvGm8nwrR3S8P0dwAhOrQaR9p7fp/lN4VjwzLgOLoowpLYw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=R+RzV6Vy; 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="R+RzV6Vy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 458E7C4CEE4; Mon, 5 May 2025 23:00:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746486058; bh=BLHcE08rHIsKAZb0PIIR3MMag85ICV+AGfZz6R+LiXU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=R+RzV6Vy1NuVN792RZj+lWpmAPm2esI8kPsXkXfS47/Eo4eGHacot2iKdxxWsITMK x5aP0kZ1dT8yWmLWCtgcVBm1xak/O1WwvVjdjq3MMydWFSBfz+scveqyb83MsHbVpY zmvqn70OdndULIQzOiaiWYUtodwZTOKBoIxKgzyImLHDp0H+JAme5EjeyR1ouJC1m6 mfY6Ct3ckunbP/1JHnyOxBbzsXnQgQrmczPBlDiUUdMt51ysSBfA3to1Lp+vzp4wpv tne0MNU4/xm0LCE/3l8IhdRFEQHoglRiEgbspNR0IXInLhJU26Yjx3EsjUyrhNXH82 y+ngM1pWNtiyg== 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 6.6 131/294] x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2 Date: Mon, 5 May 2025 18:53:51 -0400 Message-Id: <20250505225634.2688578-131-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250505225634.2688578-1-sashal@kernel.org> References: <20250505225634.2688578-1-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 6.6.89 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 184f2f96f6a54..005455d32f8da 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5960,6 +5960,8 @@ 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 78545f7e9cc6c..b14c86610b639 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1290,9 +1290,13 @@ 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; @@ -1305,7 +1309,7 @@ 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)) { @@ -1315,8 +1319,8 @@ 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_ibrs_mode(enum spectre_v2_mitigation mode) -- 2.39.5