Re: hppa lazy FPU switching and QEMU bugs

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Tue, Aug 04, 2026 at 01:03:51PM +0000, Taylor R Campbell wrote:
> > Date: Mon, 3 Aug 2026 22:57:54 -0400
> > From: Thor Lancelot Simon <tls%panix.com@localhost>
> > References: <anDzFs-VkFP_opy2%panix.com@localhost>
> > 
> > On Mon, Aug 03, 2026 at 03:59:18PM -0400, Thor Lancelot Simon wrote:
> > > 
> > > This host manages QEMU guests running the exact same version of NetBSD
> > > on 14 other emulated architectures.  Only hppa blows up like this.  I
> > > suppose some day someone will figure out why.
> > 
> > Actually the problem is not ML-KEM at all nor OpenSSL.  It's a bug in QEMU,
> > an information leak that can swap processes' FP registers!
> 
> Yes, and we already have an open PR about this:
> 
> PR port-hppa/59114: hppa: eager fpu switching for qemu and/or spectre
> mitigation
> https://gnats.NetBSD.org/59114

Well, I've got a fix - coded, unfortunately, by Claude, and it's moderately
intrusive so I will have to take a little time to re-code it per our AI
prohibition.

Or I could provide the function names and the _comments_, which are verbose,
and see if someone else wanted to have a go at it in that sort of black-box
style before I find time to.

-- 
Thor Lancelot Simon	                                     tls%panix.com@localhost
  "Indeed, someone who is a citizen in a democracy is often not one in
   an oligarchy."
					- Aristotle, Politics III.1