On 1/3/23 18:17, Sean Christopherson wrote: > On Thu, Dec 29, 2022, Michal Luczaj wrote: >> Move synchronize_srcu(&kvm->srcu) out of kvm->lock critical section. > > This needs a much more descriptive changelog, and an update to > Documentation/virt/kvm/locking.rst to define the ordering requirements between > kvm->scru and kvm->lock. And IIUC, there is no deadlock in the current code > base, so this really should be a prep patch that's sent along with the Xen series[*] > that wants to take kvm->-srcu outside of kvm->lock. > > [*] https://lore.kernel.org/all/20221222203021.1944101-2-mhal@xxxxxxx I'd be happy to provide a more descriptive changelog, but right now I'm a bit confused. I'd be really grateful for some clarifications: I'm not sure how to understand "no deadlock in the current code base". I've ran selftests[1] under the up-to-date mainline/master and I do see the deadlocks. Is there a branch where kvm_xen_set_evtchn() is not taking kvm->lock while inside kvm->srcu? Also, is there a consensus as for the lock ordering? IOW, is the state of virt/kvm/locking.rst up to date, regardless of the discussion going on[2]? [1] https://lore.kernel.org/kvm/15599980-bd2e-b6c2-1479-e1eef02da0b5@xxxxxxx/ [2] https://lore.kernel.org/kvm/Y7RpB+trpnhVRhQW@xxxxxxxxxx/ thanks, Michal
