Re: [PATCH 0/3] KVM: arm64: Assorted vgic fixes for 6.14

[Marc Zyngier <maz@kernel.org>]

On Fri, 07 Feb 2025 18:03:55 +0000,
Oliver Upton <oliver.upton@linux.dev> wrote:
> 
> On Thu, Feb 06, 2025 at 03:20:57PM +0000, Marc Zyngier wrote:
> > Alexander, while fuzzing KVM/arm64, found an annoying set of problems,
> > all stemming from the fact that the vgic can be destroyed in parallel
> > with the rest of the guest still being live.
> > 
> > Yes, this is annoying.
> > 
> > Fixing this is not going to happen overnight (though I have some
> > ideas), but we can make what we have today a bit more robust.
> > 
> > This is what patch #2 is doing. Patch #1 is just removing a loud
> > WARN_ON() that serves little purpose, and patch #3 fixes the actual
> > bug that Alex reported.
> > 
> > Hopefully, none of that is controversial...
> 
> I'm a bit grumbly about slapping bandaids on the problem, but given the
> fact that glider reported all of this a while ago and we still haven't
> fixed it is enough to justify these patches. So:

Yeah, same here. I'm starting to think that we need to either prevent
the vgic from being asynchronously destroyed, or start refcounting all
IRQs just like LPIs. Which is very annoying since we don't have a
global namespace for SGIs and PPIs.

But maybe simply refcounting the vgic itself would be enough.
Thoughts?

> Reviewed-by: Oliver Upton <oliver.upton@linux.dev>

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.