[Intel-gfx] [PATCH 3/7] vfio/pci: Allow passing zero-length fd array in VFIO_DEVICE_PCI_HOT_RESET

[Tian, Kevin]

> From: Liu, Yi L <yi.l.liu at intel.com>
> Sent: Thursday, March 16, 2023 8:42 PM
> 
> as an alternative method for ownership check when iommufd is used. In
> this case all opened devices in the affected dev_set are verified to
> be bound to a same valid iommufd value to allow reset. It's simpler
> and faster as user does not need to pass a set of fds and kernel no
> need to search the device within the given fds.
> 
> a device in noiommu mode doesn't have a valid iommufd, so this method
> should not be used in a dev_set which contains multiple devices and one
> of them is in noiommu. The only allowed noiommu scenario is that the
> calling device is noiommu and it's in a singleton dev_set.
> 
> Suggested-by: Jason Gunthorpe <jgg at nvidia.com>
> Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
> Signed-off-by: Yi Liu <yi.l.liu at intel.com>

let's hold this one until there is a consensus with Alex/Jason.