Messages in this thread | | | Date | Tue, 31 Jan 2023 09:46:18 -0500 | Subject | Re: [PATCH] kvm/vfio: Fix potential deadlock on vfio group_lock | From | Anthony Krowiak <> |
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On 1/31/23 9:34 AM, Jason Gunthorpe wrote: > On Tue, Jan 31, 2023 at 09:27:54AM -0500, Anthony Krowiak wrote: >> I encountered a lockdep splat while running some regression tests today (see >> below). I suspected it might be this patch so I reverted it, rebuilt the >> kernel and ran the regression tests again; this time, the test ran cleanly. >> It looks like this patch may not have fixed the problem for which it was >> intended. Here is the relevant dmesg output: > Well, it fixes the deadlock it intended to fix and created another one > :) > > It means device drivers cannot obtain the kvm lock from their open > functions in this new model. > > Why does ap need to touch kvm->lock? (via get_update_locks_for_kvm)
We need the kvm->lock because we take the vCPUs out of SIE in order to dynamically change values in the APCB.
> > Maybe you should split that lock and have a dedicated apcb lock?
I don't think that would suffice for taking the vCPUs out of SIE.
> > Jason
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