On 2025/6/27 06:56, Alex Williamson wrote:
In the below noted Fixes commit we introduced a reflck mutex to allow better scaling between devices for open and close. The reflck was based on the hot reset granularity, device level for root bus devices which cannot support hot reset or bus/slot reset otherwise. Overlooked in this were SR-IOV VFs, where there's also no bus reset option, but the default for a non-root-bus, non-slot-based device is bus level reflck granularity. The reflck mutex has since become the dev_set mutex and is our defacto serialization for various operations and ioctls. It still seems to be the case though that sets of vfio-pci devices really only need
a nit: not sure if mentioning 2cd8b14aaa66 which convers reflck to dev_set mutex is helpful. Perhaps, it's welcomed by people working on backporting. :)
serialization relative to hot resets affecting the entire set, which is not relevant to SR-IOV VFs. As described in the Closes link below, this serialization contributes to startup latency when multiple VFs sharing the same "bus" are opened concurrently. Mark the device itself as the basis of the dev_set for SR-IOV VFs. Reported-by: Aaron Lewis <aaronlewis@xxxxxxxxxx> Closes: https://lore.kernel.org/all/20250626180424.632628-1-aaronlewis@xxxxxxxxxx Tested-by: Aaron Lewis <aaronlewis@xxxxxxxxxx> Fixes: e309df5b0c9e ("vfio/pci: Parallelize device open and release") Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx> --- drivers/vfio/pci/vfio_pci_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Yi Liu <yi.l.liu@xxxxxxxxx> Regards, Yi Liu
