To prepare the support of region capabilities, this commit factorizes
the `VFIO_USER_DEVICE_GET_REGION_INFO` operation in its own function. In
this process, it also removes the need of the hard-coded arbitrary value
for `vfio_region_info.argsz` (the maximum size of the reply payload).
Signed-off-by: Bo Chen <chen.bo@intel.com>
Whenever a vfio-user device is dropped, the communication between the
VMM and the backend should be shutdown.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The current code was expecting a reply with only the header, which
wasn't reading the rest of payload that was provided. This was causing
the following replies to be completely wrong as they were shifted by the
previous payload that wasn't read.
The simple way to fix this issue is by reading the header and the
expected payload when getting a reply from a DmaUnmap request.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Implement (most) of the client side (i.e. VMM side) of the vfio-user
protocol:
https://github.com/nutanix/libvfio-user/blob/master/docs/vfio-user.rst
Items that are not implemented (because they are optimisations or unused
due to alternative solutions:
* VFIO_USER_DMA_READ/WRITE - this is a way for the server to read guest
memory if the guest memory is not shared by fd where the client
doesn't support it. However since we do support sharing the memory by
fd this is not required.
* VFIO_USER_GET_REGION_IO_FDS - an optimisation to bypass the VMM by
having KVM talk directly to the backend using ioregionfd
* VFIO_USER_DIRTY_PAGES - for the implementation of live migration
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
