netdev - Re: [PATCH v13 vfio 6/7] vfio/pds: Add support for firmware recovery

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Date: Fri, 4 Aug 2023 14:18:44 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Brett Creeley <brett.creeley@....com>
Cc: kvm@...r.kernel.org, netdev@...r.kernel.org, alex.williamson@...hat.com,
	yishaih@...dia.com, shameerali.kolothum.thodi@...wei.com,
	kevin.tian@...el.com, simon.horman@...igine.com,
	shannon.nelson@....com
Subject: Re: [PATCH v13 vfio 6/7] vfio/pds: Add support for firmware recovery

On Tue, Jul 25, 2023 at 02:40:24PM -0700, Brett Creeley wrote:
> It's possible that the device firmware crashes and is able to recover
> due to some configuration and/or other issue. If a live migration
> is in progress while the firmware crashes, the live migration will
> fail. However, the VF PCI device should still be functional post
> crash recovery and subsequent migrations should go through as
> expected.
> 
> When the pds_core device notices that firmware crashes it sends an
> event to all its client drivers. When the pds_vfio driver receives
> this event while migration is in progress it will request a deferred
> reset on the next migration state transition. This state transition
> will report failure as well as any subsequent state transition
> requests from the VMM/VFIO. Based on uapi/vfio.h the only way out of
> VFIO_DEVICE_STATE_ERROR is by issuing VFIO_DEVICE_RESET. Once this
> reset is done, the migration state will be reset to
> VFIO_DEVICE_STATE_RUNNING and migration can be performed.

Have you actually tested this? Does the qemu side respond properly if
this happens during a migration?

Jason