RE: [PATCH v2 00/10] Introduce new methods for verifying ownership in vfio PCI hot reset

Xu, Terrence
2023-03-31T17:27:55Z

> -----Original Message-----
> From: Liu, Yi L <yi.l.liu@intel.com>
> Sent: Monday, March 27, 2023 5:35 PM
>
> VFIO_DEVICE_PCI_HOT_RESET requires user to pass an array of group fds to
> prove that it owns all devices affected by resetting the calling device. This
> series introduces several extensions to allow the ownership check better
> aligned with iommufd and coming vfio device cdev support.
>
> First, resetting an unopened device is always safe given nobody is using it. So
> relax the check to allow such devices not covered by group fd array. [1]
>
> When iommufd is used we can simply verify that all affected devices are
> bound to a same iommufd then no need for the user to provide extra fd
> information. This is enabled by the user passing a zero-length fd array and
> moving forward this should be the preferred way for hot reset. [2]
>
> However the iommufd method has difficulty working with noiommu devices
> since those devices don't have a valid iommufd, unless the noiommu device
> is in a singleton dev_set hence no ownership check is required. [3]
>
> For noiommu backward compatibility a 3rd method is introduced by allowing
> the user to pass an array of device fds to prove ownership. [4]
>
> As suggested by Jason [5], we have this series to introduce the above stuffs
> to the vfio PCI hot reset. Per the dicussion in [6], this series also adds a new
> _INFO ioctl to get hot reset scope for given device.
>
> [1] https://lore.kernel.org/kvm/Y%2FdobS6gdSkxnPH7@nvidia.com/
> [2] https://lore.kernel.org/kvm/Y%2FZOOClu8nXy2toX@nvidia.com/#t
> [3] https://lore.kernel.org/kvm/ZACX+Np%2FIY7ygqL5@nvidia.com/
> [4]
> https://lore.kernel.org/kvm/DS0PR11MB7529BE88460582BD599DC1F7C3B19
> @DS0PR11MB7529.namprd11.prod.outlook.com/#t
> [5] https://lore.kernel.org/kvm/ZAcvzvhkt9QhCmdi@nvidia.com/
> [6] https://lore.kernel.org/kvm/ZBoYgNq60eDpV9Un@nvidia.com/
>
> Change log:
>
> v2:
> - Split the patch 03 of v1 to be 03, 04 and 05 of v2 (Jaon)
> - Add r-b from Kevin and Jason
> - Add patch 10 to introduce a new _INFO ioctl for the usage of device
> fd passing usage in cdev path (Jason, Alex)
>
> v1: https://lore.kernel.org/kvm/20230316124156.12064-1-yi.l.liu@intel.com/
>
> Regards,
> Yi Liu
>
> Yi Liu (10):
> vfio/pci: Update comment around group_fd get in
> vfio_pci_ioctl_pci_hot_reset()
> vfio/pci: Only check ownership of opened devices in hot reset
> vfio/pci: Move the existing hot reset logic to be a helper
> vfio-iommufd: Add helper to retrieve iommufd_ctx and devid for
> vfio_device
> vfio/pci: Allow passing zero-length fd array in
> VFIO_DEVICE_PCI_HOT_RESET
> vfio: Refine vfio file kAPIs for vfio PCI hot reset
> vfio: Accpet device file from vfio PCI hot reset path
> vfio/pci: Renaming for accepting device fd in hot reset path
> vfio/pci: Accept device fd in VFIO_DEVICE_PCI_HOT_RESET ioctl
> vfio/pci: Add VFIO_DEVICE_GET_PCI_HOT_RESET_GROUP_INFO
>
> drivers/iommu/iommufd/device.c | 12 ++
> drivers/vfio/group.c | 32 ++--
> drivers/vfio/iommufd.c | 16 ++
> drivers/vfio/pci/vfio_pci_core.c | 244 ++++++++++++++++++++++++-------
> drivers/vfio/vfio.h | 2 +
> drivers/vfio/vfio_main.c | 44 ++++++
> include/linux/iommufd.h | 3 +
> include/linux/vfio.h | 14 ++
> include/uapi/linux/vfio.h | 65 +++++++-
> 9 files changed, 364 insertions(+), 68 deletions(-)
>
> --
> 2.34.1

Verified this series by "Intel GVT-g GPU device mediated passthrough".
Passed VFIO legacy mode / compat mode / cdev mode basic functionality and GPU force reset test.

Tested-by: Terrence Xu <terrence.xu@intel.com>