Re: [PATCH RFC 00/12] vdpa: generalize vdpa simulator and add block device

Jason Wang
2020-11-16T03:38:14Z

On 2020/11/13 下午9:47, Stefano Garzarella wrote:
> Thanks to Max that started this work!
> I took his patches, and extended the block simulator a bit.
>
> This series moves the network device simulator in a new module
> (vdpa_sim_net) and leaves the generic functions in the vdpa_sim core
> module, allowing the possibility to add new vDPA device simulators.
> Then we added a new vdpa_sim_blk module to simulate a block device.
>
> I'm not sure about patch 11 ("vringh: allow vringh_iov_xfer() to skip
> bytes when ptr is NULL"), maybe we can add a new functions instead of
> modify vringh_iov_xfer().
>
> As Max reported, I'm also seeing errors with vdpa_sim_blk related to
> iotlb and vringh when there is high load, these are some of the error
> messages I can see randomly:
>
> vringh: Failed to access avail idx at 00000000e8deb2cc
> vringh: Failed to read head: idx 6289 address 00000000e1ad1d50
> vringh: Failed to get flags at 000000006635d7a3
>
> virtio_vdpa vdpa0: vringh_iov_push_iotlb() error: -14 offset: 0x2840000 len: 0x20000
> virtio_vdpa vdpa0: vringh_iov_pull_iotlb() error: -14 offset: 0x58ee000 len: 0x3000
>
> These errors should all be related to the fact that iotlb_translate()
> fails with -EINVAL, so it seems that we miss some mapping.

Is this only reproducible when there's multiple co-current accessing of
IOTLB? If yes, it's probably a hint that some kind of synchronization is
still missed somewhere.

It might be useful to log the dma_map/unmp in both virtio_ring and
vringh to see who is missing the map.

Thanks

>
> I'll debug more carefully, in the meantime can you give a first review?
>
> Thanks,
> Stefano
>
> Max Gurtovoy (4):
> vhost-vdpa: add support for vDPA blk devices
> vdpa: split vdpasim to core and net modules
> vdpa_sim: remove hard-coded virtq count
> vdpa: add vdpa simulator for block device
>
> Stefano Garzarella (8):
> vdpa_sim: remove the limit of IOTLB entries
> vdpa_sim: add struct vdpasim_device to store device properties
> vdpa_sim: move config management outside of the core
> vdpa_sim: use kvmalloc to allocate vdpasim->buffer
> vdpa_sim: make vdpasim->buffer size configurable
> vdpa_sim: split vdpasim_virtqueue's iov field in riov and wiov
> vringh: allow vringh_iov_xfer() to skip bytes when ptr is NULL
> vdpa_sim_blk: implement ramdisk behaviour
>
> drivers/vdpa/vdpa_sim/vdpa_sim.h | 117 +++++++++++
> drivers/vdpa/vdpa_sim/vdpa_sim.c | 283 +++++----------------------
> drivers/vdpa/vdpa_sim/vdpa_sim_blk.c | 251 ++++++++++++++++++++++++
> drivers/vdpa/vdpa_sim/vdpa_sim_net.c | 172 ++++++++++++++++
> drivers/vhost/vdpa.c | 11 +-
> drivers/vhost/vringh.c | 16 +-
> drivers/vdpa/Kconfig | 16 +-
> drivers/vdpa/vdpa_sim/Makefile | 2 +
> 8 files changed, 628 insertions(+), 240 deletions(-)
> create mode 100644 drivers/vdpa/vdpa_sim/vdpa_sim.h
> create mode 100644 drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
> create mode 100644 drivers/vdpa/vdpa_sim/vdpa_sim_net.c