linux-kernel - Re: [PATCH AUTOSEL 5.15 11/12] x86/barrier: Do not serialize MSR accesses on AMD

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241129133054.GCZ0nCDrwBN0wpjP4t@fat_crate.local>
Date: Fri, 29 Nov 2024 14:30:54 +0100
From: Borislav Petkov <bp@...en8.de>
To: Sasha Levin <sashal@...nel.org>
Cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	tglx@...utronix.de, mingo@...hat.com, dave.hansen@...ux.intel.com,
	x86@...nel.org, puwen@...on.cn, seanjc@...gle.com,
	kim.phillips@....com, jmattson@...gle.com, babu.moger@....com,
	peterz@...radead.org, rick.p.edgecombe@...el.com, brgerst@...il.com,
	ashok.raj@...el.com, mjguzik@...il.com, jpoimboe@...nel.org,
	nik.borisov@...e.com, aik@....com, vegard.nossum@...cle.com,
	daniel.sneddon@...ux.intel.com, acdunlap@...gle.com,
	Erwan Velu <erwanaliasr1@...il.com>, pavel@...x.de
Subject: Re: [PATCH AUTOSEL 5.15 11/12] x86/barrier: Do not serialize MSR
 accesses on AMD

On Thu, Nov 28, 2024 at 07:21:50PM -0500, Sasha Levin wrote:
> Suggestions welcome... I don't really insist on a massive flood and was
> mostly following what was the convention when I started doing this work.
> 
> I thought about cutting it down to one mail per commit, but OTOH I had
> folks complain often enough that they missed a mail or that it wasn't
> obvious enough.

I don't know. It is a lot of mail and I doubt people look at most of them but
it's not like cutting down the mails from stable will alleviate the general
firehose drinking situation so...

> It might be all those thanksgiving drinks, but I can't find it in
> 5.15... I see it was part of 6.7.6 and 6.6.18, but nothing older.

Sorry, I meant 6.6.

> The stable kernel rules allow for "notable" performance fixes, and we
> already added it to 6.6.

Frankly, I don't have anything smarter than "well, it needs to be decided on
a case-by-case basis." As Erwan confirms, it really brings perf improvements
for their use case. So I guess that's a reason good enough to backport it
everywhere.

But cutting a general rule about such patches...? Nope, I can't think of any
good one.

> No objection to adding it to older kernels...
> 
> Happy to do it after the current round of releases goes out.

Thanks.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette