On Thu, Aug 05 2021, Jason Gunthorpe jgg@nvidia.com wrote:
vfio_pci_try_bus_reset() is triggering a reset of the entire_dev set if any device within it has accumulated a needs_reset. This reset can only be done once all of the drivers operating the PCI devices to be reset are in a known safe state.
Make this clearer by directly operating on the dev_set instead of the vfio_pci_device. Rename the function to vfio_pci_dev_set_try_reset().
Use the device list inside the dev_set to check that all drivers are in a safe state instead of working backwards from the pci_device.
The dev_set->lock directly prevents devices from joining/leaving the set, or changing their state, which further implies the pci_device cannot change drivers or that the vfio_device be freed, eliminating the need for get/put's.
If a pci_device to be reset is not in the dev_set then the reset cannot be used as we can't know what the state of that driver is. Directly measure this by checking that every pci_device is in the dev_set - which effectively proves that VFIO drivers are attached to everything.
Remove the odd interaction around vfio_pci_set_power_state() - have the only caller avoid its redundant vfio_pci_set_power_state() instead of avoiding it inside vfio_pci_dev_set_try_reset().
This restructuring corrects a call to pci_dev_driver() without holding the device_lock() and removes a hard wiring to &vfio_pci_driver.
Signed-off-by: Jason Gunthorpe jgg@nvidia.com
drivers/vfio/pci/vfio_pci.c | 182 +++++++++++++++++------------------- 1 file changed, 86 insertions(+), 96 deletions(-)
Reviewed-by: Cornelia Huck cohuck@redhat.com