On Tue, Jul 20 2021, Jason Gunthorpe jgg@nvidia.com wrote:
Currently the driver ops have an open/release pair that is called once each time a device FD is opened or closed. Add an additional set of open/close_device() ops which are called when the device FD is opened for the first time and closed for the last time.
An analysis shows that all of the drivers require this semantic. Some are open coding it as part of their reflck implementation, and some are just buggy and miss it completely.
To retain the current semantics PCI and FSL depend on, introduce the idea of a "device set" which is a grouping of vfio_device's that share the same lock around opening.
The device set is established by providing a 'set_id' pointer. All vfio_device's that provide the same pointer will be joined to the same singleton memory and lock across the whole set. This effectively replaces the oddly named reflck.
After conversion the set_id will be sourced from:
- A struct device from a fsl_mc_device (fsl)
- A struct pci_slot (pci)
- A struct pci_bus (pci)
- The struct vfio_device (everything)
The design ensures that the above pointers are live as long as the vfio_device is registered, so they form reliable unique keys to group vfio_devices into sets.
This implementation uses xarray instead of searching through the driver core structures, which simplifies the somewhat tricky locking in this area.
Following patches convert all the drivers.
Signed-off-by: Yishai Hadas yishaih@nvidia.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com
drivers/vfio/mdev/vfio_mdev.c | 22 +++++ drivers/vfio/vfio.c | 146 +++++++++++++++++++++++++++++----- include/linux/mdev.h | 2 + include/linux/vfio.h | 19 +++++ 4 files changed, 167 insertions(+), 22 deletions(-)
Reviewed-by: Cornelia Huck cohuck@redhat.com