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 61B252EAB97; Tue, 12 Aug 2025 18:30:33 +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=1755023433; cv=none; b=Bg0uOz45h67TS36B21dO9ha7GHcNOG8WRZW1OSwAL6YsUT3ZaF0JoK6v7YM5hylS5pUxzI68YJeskHzRh567GsWZ7MQm2BaH3vLP7l3eX7Uv81JY7iIcg0A0nHjUmI8JV61PcttYNk8gT1bvkZ26le1sQtWU5qMw0r86H5rHS40= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755023433; c=relaxed/simple; bh=vtBo/Jyxv8tJwML59EFapwx2VOd/I73lIte98MWWfnc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HdLFDwCea6KCPKOit1annE8xN3/JLfDba1meFPsusTeXh9dl6ZGOKsVjch++G+wzluXvUQv5LxdxyCsLwvB/4kMdtk8JhHvMC6HqXoLQw7ybwAX13HKvgfT4vXogsfHOORzC+hxMWnj54DiSgPV3j1ky7k5YGU7DCswJQXh/xeA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=J6+vXzYu; 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="J6+vXzYu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9FB8FC4CEF0; Tue, 12 Aug 2025 18:30:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755023433; bh=vtBo/Jyxv8tJwML59EFapwx2VOd/I73lIte98MWWfnc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=J6+vXzYuwmjRoEeLQhpIkntKrBHPmueA4Pou6yILZiYbJcQP1yL81kdCMmuqeRVyL obvYcpEGcjKHsD3BYbm2iMiwzTFUCkxMFbp+fkSaT1zaok4bup/0ZbWWQJELugP31s uxInsFOHJIKm5wJ85EHtWhmHHMazzUttuYyorRCA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Borislav Petkov , Pawan Gupta , Sasha Levin Subject: [PATCH 6.16 061/627] x86/bugs: Avoid AUTO after the select step in the retbleed mitigation Date: Tue, 12 Aug 2025 19:25:56 +0200 Message-ID: <20250812173421.647752381@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250812173419.303046420@linuxfoundation.org> References: <20250812173419.303046420@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pawan Gupta [ Upstream commit 98ff5c071d1cde9426b0bfa449c43d49ec58f1c4 ] The retbleed select function leaves the mitigation to AUTO in some cases. Moreover, the update function can also set the mitigation to AUTO. This is inconsistent with other mitigations and requires explicit handling of AUTO at the end of update step. Make sure a mitigation gets selected in the select step, and do not change it to AUTO in the update step. When no mitigation can be selected leave it to NONE, which is what AUTO was getting changed to in the end. Suggested-by: Borislav Petkov Signed-off-by: Pawan Gupta Signed-off-by: Borislav Petkov (AMD) Acked-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/20250611-eibrs-fix-v4-1-5ff86cac6c61@linux.intel.com Stable-dep-of: ab9f2388e0b9 ("x86/bugs: Allow ITS stuffing in eIBRS+retpoline mode also") Signed-off-by: Sasha Levin --- arch/x86/kernel/cpu/bugs.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index f4d3abb12317..0bf2566d21b6 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1251,6 +1251,14 @@ static void __init retbleed_select_mitigation(void) retbleed_mitigation = RETBLEED_MITIGATION_IBPB; else retbleed_mitigation = RETBLEED_MITIGATION_NONE; + } else if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) { + /* Final mitigation depends on spectre-v2 selection */ + if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) + retbleed_mitigation = RETBLEED_MITIGATION_EIBRS; + else if (boot_cpu_has(X86_FEATURE_IBRS)) + retbleed_mitigation = RETBLEED_MITIGATION_IBRS; + else + retbleed_mitigation = RETBLEED_MITIGATION_NONE; } } @@ -1259,9 +1267,6 @@ static void __init retbleed_update_mitigation(void) if (!boot_cpu_has_bug(X86_BUG_RETBLEED) || cpu_mitigations_off()) return; - if (retbleed_mitigation == RETBLEED_MITIGATION_NONE) - goto out; - /* * retbleed=stuff is only allowed on Intel. If stuffing can't be used * then a different mitigation will be selected below. @@ -1272,7 +1277,7 @@ static void __init retbleed_update_mitigation(void) its_mitigation == ITS_MITIGATION_RETPOLINE_STUFF) { if (spectre_v2_enabled != SPECTRE_V2_RETPOLINE) { pr_err("WARNING: retbleed=stuff depends on spectre_v2=retpoline\n"); - retbleed_mitigation = RETBLEED_MITIGATION_AUTO; + retbleed_mitigation = RETBLEED_MITIGATION_NONE; } else { if (retbleed_mitigation != RETBLEED_MITIGATION_STUFF) pr_info("Retbleed mitigation updated to stuffing\n"); @@ -1298,15 +1303,11 @@ static void __init retbleed_update_mitigation(void) if (retbleed_mitigation != RETBLEED_MITIGATION_STUFF) pr_err(RETBLEED_INTEL_MSG); } - /* If nothing has set the mitigation yet, default to NONE. */ - if (retbleed_mitigation == RETBLEED_MITIGATION_AUTO) - retbleed_mitigation = RETBLEED_MITIGATION_NONE; } -out: + pr_info("%s\n", retbleed_strings[retbleed_mitigation]); } - static void __init retbleed_apply_mitigation(void) { bool mitigate_smt = false; -- 2.39.5