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

[Stefano Garzarella]

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.

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

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2.26.2