On Thu, 5 Aug 2021 22:18:56 -0300 Jason Gunthorpe <jgg@xxxxxxxxxx> wrote: > 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. > > The special behavior of PCI around the bus/slot "reset group" is recast in > terms of the device set which conslidates the reflck, eliminates two > touches of pci_dev_driver(), and allows the reset mechanism to share > across all VFIO PCI drivers. PCI is changed to acquire devices directly > from the device set instead of trying to work backwards from the struct > pci_device. > > Overall a few minor bugs are squashed and quite a bit of code is removed > through consolidation. > > v4: > - Fix use-after-free typo in mbochs error unwind > - Allow mdevs to work when they don't have open/release ops, for > bisect-ability > - Redo the vfio_pci_try_bus_reset() patch, make it dev_set centric > - Change VFIO_DEVICE_PCI_HOT_RESET to align with the new > vfio_pci_try_bus_reset() design Applied to vfio next branch for v5.15 with Connie and Christoph's additional Reviewed-bys. Thanks, Alex
