[PATCH 0/4] KVM: arm64: vgic: Locking fixes

[Marc Zyngier]

On Thu, 18 May 2023 11:09:14 +0100,
Jean-Philippe Brucker <jean-philippe at linaro.org> wrote:
> 
> Another fun locking puzzle, between the new config_lock and srcu.
> Patch 1 attempts to fix it, and the other patches fix simpler issues.

Thanks for that and for your excellent description of the problems.

> I got these lockdep reports while running KVM QEMU on a TCG QEMU, but it
> can also be triggered by running the vgic_irq kselftest on TCG QEMU.
> Now, with the fix and lockdep enabled, vgic_irq hangs but I believe it's
> an unrelated weirdness: if I introduce a separate lockdep warning for
> some made up locks, then the test passes again. So I'm sending this out
> now for discussion, and will investigate that one later.

I've taken these patches for a spin, and I cannot reproduce this hang,
though I'm running on actual HW and not QEMU. It would be really
annoying if lockdep actively introduced issues... :-/

Any chance you could dig into this as you have a good reproducer? I'll
try to setup a TGC environment on my end as well.

Thanks,

	M.

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