On 7/15/2021 5:50 AM, Jason Gunthorpe wrote:
Prologue:
This is the first series of three to send the "mlx5_vfio_pci" driver that has
been discussed on the list for a while now.
- Reorganize reflck to support splitting vfio_pci
- Split vfio_pci into vfio_pci/vfio_pci_core and provide infrastructure
for non-generic VFIO PCI drivers
- The new driver mlx5_vfio_pci that is a full implementation of
suspend/resume functionality for mlx5 devices.
A preview of all the patches can be seen here:
https://github.com/jgunthorpe/linux/commits/mlx5_vfio_pci
===============
This is in support of Max's series to split vfio-pci. For that to work the
reflck concept embedded in vfio-pci needs to be sharable across all of the
new VFIO PCI drivers which motivated re-examining how this is
implemented.
Another significant issue is how the VFIO PCI core includes code like:
if (pci_dev_driver(pdev) != &vfio_pci_driver)
Which is not scalable if there are going to be multiple different driver
types.
This series takes the approach of moving the "reflck" mechanism into the
core code as a "device set". Each vfio_device driver can specify how
vfio_devices are grouped into the set using a key and the set comes along
with a set-global mutex. The core code manages creating per-device set
memory and associating it with each vfio_device.
In turn this allows the core code to provide an open/close_device()
operation that is called only for the first/last FD, and is called under
the global device set lock.
Review of all the drivers show that they are either already open coding
the first/last semantic or are buggy and missing it. All drivers are
migrated/fixed to the new open/close_device ops and the unused per-FD
open()/release() ops are deleted.
Why can't open()/release() ops be reused instead of adding
open_device()/close_device().
Thanks,
Kirti
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