From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (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 29DE252E046; Tue, 13 Oct 2026 23:07:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791932850; cv=none; b=R57IuXy41HpY7HTsYqM3dAb6GH1vrNH3obVpjiux2VccJDxAWpejjHh0WUURT+A4fU0kZ4hajm2iL80sw1kGfUleWf7GuZpsmC215ttP1hn6nSI+iF4PXWcXHe97TG8okPpSGaDEiGMpVlXcAeWvNyf4xEmbAutFXotFFj2JnqE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791932850; c=relaxed/simple; bh=3y7Xw7YkNHnuviBgkfoYmKWc1LtddiF+VIJ9Q5vJFCI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=AGGGf1V/ukRxL4i2/NMVdReXpCDL4H9zxYf0TRZiqyQFezI6aIAWmeeIGwS90lgdd/rkPGsENwHq7iebT5UUTdJt/v1NBgB/iz5LB3IcG2X2EJcmSF+3A55AYZGVIpxlsk/56YxLgDWOtFuJltEQOgKGyWsmD2663SIV6Tjz0gY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=TzF5CbIh; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="TzF5CbIh" Received: from [IPV6:2601:646:8003:f231:356f:4b4f:2ec9:d15a] ([IPv6:2601:646:8003:f231:356f:4b4f:2ec9:d15a]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 69DN6o573850101 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Tue, 13 Oct 2026 16:06:50 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 69DN6o573850101 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2026092801; t=1791932812; bh=JJmD+/QY5os8wQkB/X/NCAurpKkUQhavruhI2yQUGvA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=TzF5CbIhbMJrANvDVDlsjrXZffPmaHwe6HTcaeZpFw0yw+73stVWu3k82+jxkOrGy YTHVCg8DGFcK4PL35piseSZW4rYX7/REXaxlyZrGZwh2IFfJDOGqZxPiYQhgmf47al Z3aYh4AzgBYpGLKe2kB0uHjvc4J9MAi+cTmneTGlJUqrdwSnbsgzItKQUW3TpC5Zow 0Nt2KoYcLIBxM2hWp14omb6TjNa4mTI/5rmopZSRZ+dR688jlyFw2WqGHi2JppdGr5 gJonWVvvwT68a1D7RXLYudQyZlKZKkVRRb16zSlevHkkkrfSt0aPp+rKE8WF0jcwTT X5j/GO9BCA8Wg== Message-ID: <59691ed7-1da5-44b4-8b6b-c7eae92b6161@zytor.com> Date: Tue, 13 Oct 2026 16:06:44 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] selftests/x86: Add a test for LASS enforcement To: Sohil Mehta , x86@kernel.org, Borislav Petkov , Dave Hansen Cc: Thomas Gleixner , Ingo Molnar , Shuah Khan , Binbin Wu , Peter Zijlstra , "Chang S . Bae" , Kishen Maloor , Sean Christopherson , Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20261009020025.4175228-1-sohil.mehta@intel.com> Content-Language: en-US, sv-SE From: "H. Peter Anvin" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2026-10-13 12:51, Sohil Mehta wrote: > > I had it in v1 of this patch. It seemed excessive to do specifically for > LASS: > https://lore.kernel.org/lkml/20260806011536.4172258-8-sohil.mehta@intel.com/ > "Specificially for LASS" is the problem here. This goes under the "do it generally, do it right, do it once." Librarize it. > I agree, adding them as generic selftest helpers may be useful. But, > /proc/cpuinfo has been unreliable in general. It is currently buggy for > some features with Kconfig options. See: > > https://lore.kernel.org/lkml/f6f113b46199d996c4f81fc89858c2f484256418.1774623092.git.m.wieczorretman@pm.me/ > Also, (I think) we have been generally discouraging folks to add more > bits there. So, I don't know if creating these library routines is > useful right now. IIUC, Boris said that the CPUID rework would make some > of cpuinfo stuff moot. > > https://lore.kernel.org/lkml/20260331140216.GDacvT6IPW1gf003z-@fat_crate.local/ > Thoughts? This is a great example of why these interfaces *are* useful and why they *should* be fixed. -hpa