linux-kernel - Re: [PATCH] x86/vmware: Fix hypercall clobbers

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: <cjacqm5kz67e3nrjfxhpe4lepr27cnbmykdixknta4r2wh7ugq@3wne235ikkb7>
Date: Fri, 23 Jan 2026 09:35:08 -0800
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Thorsten Leemhuis <regressions@...mhuis.info>
Cc: Alexey Makhalov <alexey.makhalov@...adcom.com>, x86@...nel.org, 
	linux-kernel@...r.kernel.org, Ajay Kaher <ajay.kaher@...adcom.com>, 
	bcm-kernel-feedback-list@...adcom.com, Peter Zijlstra <peterz@...radead.org>, 
	Justin Forbes <jforbes@...oraproject.org>, Linux kernel regressions list <regressions@...ts.linux.dev>
Subject: Re: [PATCH] x86/vmware: Fix hypercall clobbers

On Fri, Jan 23, 2026 at 10:47:18AM +0100, Thorsten Leemhuis wrote:
> [CCing the regression list]
> 
> On 1/22/26 11:00, Alexey Makhalov wrote:
> > 
> > Thanks for reporting the problem.
> > [...] 
> > Workarounding QEMU misbehavior from the kernel side by introducing less
> > efficient asm inlines does not sound correct.
> 
> Well, fixing bugs right where they are obviously is a good thing.
> 
> But well, the problem according to the description quoted below was
> exposed by a change that went into 6.19-rc1 -- which makes it a kernel
> regression that must be fixed in the kernel (ideally before 6.19 is out).
> 
> At least from my understanding of Linus point of view on situations like
> that. Or am I mistaken for some reason?
> 
> Or is this a case of "we for now assume this is such a corner case that
> nobody else will hit; if we are wrong we'll reconsider".

Hm, yes, from that perspective I agree this is a kernel regression that
needs fixed.  We still want Linux to work with older "broken" versions
of qemu that clobber registers.

-- 
Josh