Re: [RFC PATCH 07/19] vfio/pci: Retry BAR faults after temporary recovery

[sashiko-bot@kernel.org]

> A guest can fault on a mapped BAR while host recovery is running. Do not
> insert the PFN in that case. The device is not usable until recovery is
> finished.
> 
> Wait whenever access is blocked, not only while a recovery transaction is
> in progress. A function reset blocks access without starting one, and
> error_detected() blocks it before it publishes the flags, so a fault in
> either window would otherwise fail for good. Only a closed device, or one
> which has failed for good, ends the fault, which is what
> VFIO_PCI_RECOVERY_FAILED records.
> 
> On the first attempt the fault lock can be dropped, so drop it, wait for
> recovery, and return VM_FAULT_RETRY to bring the fault back later. The
> wait is killable. Take a reference on the device registration before
> dropping the lock, because the wait outlives the lock and the device
> [ ... ]
> revoke everything, and the fault would then map a PFN for a device which
> was already revoked.
> 
> Assisted-by: Claude:claude-opus-5
> Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260901093217.8539-1-skolothumtho@nvidia.com?part=7