From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.alien8.de (mail.alien8.de [65.109.113.108]) (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 1D17238AC79 for ; Thu, 14 May 2026 17:15:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=65.109.113.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778778934; cv=none; b=kmY3botbXCVp87fj72a8u1mq9/5h46JKAO9INzig7H08lfJ4yKkf7TilDpDKGxM5Ei6qJFtoNfgxMeFKqZbSELhUFebyvT9eHqwUHaPMTsPVoWn7l3skJ2rok2j5q19Q84M4dZNOTwjznXCDgbxhVeePg65nTrTHKMH19t/cNj4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778778934; c=relaxed/simple; bh=xQWTgFrxKOPYoRPZn2o90yrbM9o86TkAkXDYrEGFcFo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UGHJWKqsFy6DKFGId1PDZO+vb25O15pddMgrYHbC/5avL7CNMWKogp3d1t9Uqx0mrsf+LEGyp6ugiYQ/y7IHrdguPaoIVoeyPuV0htPXUPmw8XlN78JsjlouNcUvlxlXPfSOODk5H83arxfVH91W5Q2/x6H+tsCYED4ihvEnZw0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de; spf=pass smtp.mailfrom=alien8.de; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b=W0Kge71j; arc=none smtp.client-ip=65.109.113.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=alien8.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b="W0Kge71j" Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTP id 0936240E01A1; Thu, 14 May 2026 17:15:31 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at mail.alien8.de Authentication-Results: mail.alien8.de (amavisd-new); dkim=pass (4096-bit key) header.d=alien8.de Received: from mail.alien8.de ([127.0.0.1]) by localhost (mail.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id oPN8xXX5putU; Thu, 14 May 2026 17:15:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=alien8; t=1778778921; bh=eoJ1uGu1IQ4lW2ITGYsVKIabvk4Jarsg5gYdlasR9+U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=W0Kge71j0fhkB9dIMxtZilfqjZfN9xBdxxkFFvlMSkqvowOuhBNCHxr7EY6LRHLNL PEG8pBqf2513HPXuMn/V823cwQDXQznKTJNKgfJSpcUOQ8glKgeKY59efQvDI8bsiu QCKymg9qCHYblHhu68Q85lVbg4WiNobINLd7sYKUIFONWOgrZsHl/EbIn8D4zKMpY/ oHkYpd7Qzyb1U9banyo5SyIIl4uwXL+NEoAh7JhdBmcL+WvTPwIZfOtdwN3/uWhTxe bJWnZHYxIiI6g22vpNnRTSxKEX7btk6fCYWjKlQIehOv7rhIqwyH4RMmWNyn8pU8N9 tPKj86TJqNuRA8m7T1UEXhzwFAxC/AxaJ8Qh4Zb3YdmPK4FXqDU3fkOFe0PxfuLkXB LIq7cf38GwGWVYOEyj+BzxqTzeyalTkalDgo234VoAo8ytj9U5qwkLvdC8Bw1EAwu/ 52vKhNf0SlZrAwpGcXLaO5i/S6qStnpIqZ3t9ohf2CWmNifqFD1dgI2eBIsQE4rw22 +mouNJDgHntDHUSag+dUfCsqYiLZ+fojMgc3EogwKV07hVyZlcwJOBwatUdENskzYM apoayOuI7XaSmf13XS5XPnn3plcCzsiNwI/W/+lGj1WkaeqsgwcfT/NPw8OAqLaYGS 29zRTTTrfXV3rJOaqodUYBbw= Received: from zn.tnic (pd953014d.dip0.t-ipconnect.de [217.83.1.77]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with UTF8SMTPSA id F046040E00C2; Thu, 14 May 2026 17:15:12 +0000 (UTC) Date: Thu, 14 May 2026 19:15:12 +0200 From: Borislav Petkov To: "Edgecombe, Rick P" Cc: "minipli@grsecurity.net" , "peterz@infradead.org" , "mingo@redhat.com" , "tglx@kernel.org" , "linux-kernel@vger.kernel.org" , "dave.hansen@linux.intel.com" , "x86@kernel.org" Subject: Re: [PATCH v3] x86/cpufeatures: Make X86_FEATURE_SHSTK clearcpuid-able Message-ID: <20260514171512.GIagYDIPZtw33R2YwL@fat_crate.local> References: <20260514160932.91556-1-minipli@grsecurity.net> <20260514165922.GGagX_amNCc0mZcz4d@fat_crate.local> <8380b063f933ac3b909b6a5c9adfa03a116da1f7.camel@intel.com> <20260514171256.GHagYCmFMsc1FYZ57B@fat_crate.local> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260514171256.GHagYCmFMsc1FYZ57B@fat_crate.local> I would even want to do that. Just so that people don't get silly ideas... diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 4d0f545fb3ec..97007f4f69d4 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -789,24 +789,6 @@ Kernel parameters cio_ignore= [S390] See Documentation/arch/s390/common_io.rst for details. - clearcpuid=X[,X...] [X86] - Disable CPUID feature X for the kernel. See - arch/x86/include/asm/cpufeatures.h for the valid bit - numbers X. Note the Linux-specific bits are not necessarily - stable over kernel options, but the vendor-specific - ones should be. - X can also be a string as appearing in the flags: line - in /proc/cpuinfo which does not have the above - instability issue. However, not all features have names - in /proc/cpuinfo. - Note that using this option will taint your kernel. - Also note that user programs calling CPUID directly - or using the feature without checking anything - will still see it. This just prevents it from - being used by the kernel or shown in /proc/cpuinfo. - Also note the kernel might malfunction if you disable - some critical bits. - clk_ignore_unused [CLK] Prevents the clock framework from automatically gating -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette