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 E5CE1221727; Mon, 2 Jun 2025 14:55:26 +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=1748876127; cv=none; b=pGok7v0wzZ3ilO+zNwoJLorQ2y0MghjwHAInYi1yKHYxRGufQVxeVSt0g8cqIp9/ycIDW4AUaMmsD0xybMSaW7wxfrwy1X0vNE5Thf8OtPs1e8s/9c9EYHWguz/I9iWXySGrFQ+UD2qPYM+a25xik/nXWVESkGZnnnO95MXWQq4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748876127; c=relaxed/simple; bh=7NfbzEc6UHcl1WO4+MdZaL2pF2e8qzJTWm1fAuq/VOA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Yp7qZDPj3hNaPXkCKYzzBy+K//5AmYIfgPqlt0NW0ftdyWzocTSgCahvLbGlrveIyjtX561vxHJv1mToMOSlWqUbAd8l2Ayuz6XF7hntgT3fc0waBIwjkbdtC0rhM0Uf0XXP/1sdMqAuRff5nW7jiuxEgMivbaKg7O0LLfZDPQU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=w6fimMjM; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="w6fimMjM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 62DBCC4CEEB; Mon, 2 Jun 2025 14:55:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1748876126; bh=7NfbzEc6UHcl1WO4+MdZaL2pF2e8qzJTWm1fAuq/VOA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=w6fimMjMeanCUrwNowqcSBlA9un2++lD6JtLfKycUSE975Vuv/aV7lXLuZ9ObwOcW LO2CyjrlhvDh/RCtCPcHf+4zSyY4Cjx7/2RR3cwQVXXghnchUjYtJ0uKOW1mWZAPHv Fm6bIKnvTVLONpA9wXv2qSRZxMjUFYTswo98gCCs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Breno Leitao , Ingo Molnar , Pawan Gupta , Josh Poimboeuf , Peter Zijlstra , David Kaplan , Sasha Levin Subject: [PATCH 5.15 079/207] x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2 Date: Mon, 2 Jun 2025 15:47:31 +0200 Message-ID: <20250602134301.829509606@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250602134258.769974467@linuxfoundation.org> References: <20250602134258.769974467@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ 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 4bc5d8c97d097..e0670357d23f8 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5445,6 +5445,8 @@ 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 63af3d73d19e5..30b9292ac58fd 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1382,9 +1382,13 @@ 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; @@ -1397,7 +1401,7 @@ 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)) { @@ -1407,8 +1411,8 @@ 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