On Wed, Oct 22, 2025 at 02:55:18PM +0200, Eugenio Perez Martin wrote: > On Wed, Oct 22, 2025 at 1:43 PM Michael S. Tsirkin <[email protected]> wrote: > > > > On Wed, Oct 22, 2025 at 12:50:53PM +0200, Eugenio Perez Martin wrote: > > > Let me switch to MQ as I think it illustrates the point better. > > > > > > IIUC the workflow: > > > a) virtio-net sends MQ_VQ_PAIRS_SET 2 to the device > > > b) VDUSE CVQ sends ok to the virtio-net driver > > > c) VDUSE CVQ sends the command to the VDUSE device > > > d) Now the virtio-net driver sends virtio-net sends MQ_VQ_PAIRS_SET 1 > > > e) VDUSE CVQ sends ok to the virtio-net driver > > > > > > The device didn't process the MQ_VQ_PAIRS_SET 1 command at this point, > > > so it potentially uses the second rx queue. But, by the standard: > > > > > > The device MUST NOT queue packets on receive queues greater than > > > virtqueue_pairs once it has placed the VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET > > > command in a used buffer. > > > > > > So the driver does not expect rx buffers on that queue at all. From > > > the driver's POV, the device is invalid, and it could mark it as > > > broken. > > > > ok intresting. Note that if userspace processes vqs it should process > > cvq too. I don't know what to do in this case yet, I'm going on > > vacation, let me ponder this a bit. > > > > Sure.
So let me ask you this, how are you going to handle device reset? Same issue, it seems to me. -- MST
