HI Maxime,

My name is Chris Brezovec, we met and talked about some 32 bit virtio issues we were seeing at Cisco during the DPDK summit last year.  There was also a back and forth between you and Dave Johnson at Cisco last September regarding the same issue.  I have attached some of the email chain from that conversation that resulted in this commit being made to dpdk v23.11 (https://github.com/DPDK/dpdk/commit/8c41645be010ec7fa0df4f6c3790b167945154b4).

We recently picked up the v23.11.1 DPDK release and saw that 32 bit virtio is not working again, but 64-bit virtio is working.  We are noticing CVQ timeouts - PMD receives no response from host and this leads to failure of the port to start.  We were able to recreate this issue using testpmd.  We have done some tracing through the virtio changes made during the development of the v23.xx DPDK release, and believe we have identified the following rework commit to have caused a failure (https://github.com/DPDK/dpdk/commit/a632f0f64ffba3553a18bdb51a670c1b603c0ce6).

We have also tested v23.07, v23.11, v23.11.2-rc2, v24.07 and they all seem to see the same issue when running in 32-bit mode using testpmd.

We were hoping you might be able to take a quick look at the two commits and see if there might be something obvious missing in the refactor work that might have caused this issue.  I am thinking there might a location or two in the code that should be using the VIRTIO_MBUF_ADDR() or similar macro that might have been missed.

Regards,

ChrisB

This is some of the testpmd output seen on v23.11.2-rc2:

LD_LIBRARY_PATH=/home/rmelton/scratch/dpdk-v23.11.2-rc2.git/build/lib /home/rmelton/scratch/dpdk-v23.11.2-rc2.git/build/app/dpdk-testpmd -l 2-3 -a 0000:07:00.0 --log-level pmd.net.iavf.*,8 --log-level lib.eal.*,8 --log-level=lib.eal:info --log-level=lib.eal:debug --log-level=lib.ethdev:info --log-level=lib.ethdev:debug --log-level=lib.virtio:warning --log-level=lib.virtio:info --log-level=lib.virtio:debug --log-level=pmd.*:debug --iova-mode=pa -- -i

— snip —

virtio_send_command(): vq->vq_desc_head_idx = 0, status = 255, vq->hw->cvq = 0x76d9acc0 vq = 0x76d9ac80

virtio_send_command_split(): vq->vq_queue_index = 2

virtio_send_command_split(): vq->vq_free_cnt=64

vq->vq_desc_head_idx=0

virtio_dev_promiscuous_disable(): Failed to disable promisc

Failed to disable promiscuous mode for device (port 0): Resource temporarily unavailable

Error during restoring configuration for device (port 0): Resource temporarily unavailable

virtio_dev_stop(): stop

Fail to start port 0: Resource temporarily unavailable

Done

virtio_send_command(): vq->vq_desc_head_idx = 0, status = 255, vq->hw->cvq = 0x76d9acc0 vq = 0x76d9ac80

virtio_send_command_split(): vq->vq_queue_index = 2

virtio_send_command_split(): vq->vq_free_cnt=64

vq->vq_desc_head_idx=0

virtio_dev_promiscuous_enable(): Failed to enable promisc

Error during enabling promiscuous mode for port 0: Resource temporarily unavailable - ignore