Re: [RFC] virtio_scsi: to poll and kick the virtqueue in timeout handler

[Hannes Reinecke]

On 5/23/21 8:38 AM, Dongli Zhang wrote:
> This RFC is to trigger the discussion about to poll and kick the
> virtqueue on purpose in virtio-scsi timeout handler.
>
> The virtio-scsi relies on the virtio vring shared between VM and host.
> The VM side produces requests to vring and kicks the virtqueue, while the
> host side produces responses to vring and interrupts the VM side.
>
> By default the virtio-scsi handler depends on the host timeout handler
> by BLK_EH_RESET_TIMER to give host a chance to perform EH.
>
> However, this is not helpful for the case that the responses are available
> on vring but the notification from host to VM is lost.
How can this happen?
If responses are lost the communication between VM and host is broken, 
and we should rather reset the virtio rings themselves.

Cheers,

Hannes
--
Dr. Hannes Reinecke                Kernel Storage Architect
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