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. While for cdev devices, user can use an iommufd-based ownership checking model and invoke VFIO_DEVICE_PCI_HOT_RESET with a zero-length fd array. This series extends VFIO_DEVICE_GET_PCI_HOT_RESET_INFO to check ownership and return the check result and the devid of affected devices to user. In the end, extends the VFIO_DEVICE_PCI_HOT_RESET to accept zero-length fd array for hot-reset with cdev devices. The new hot reset method and updated _INFO ioctl are tested with the below qemu: https://github.com/yiliu1765/qemu/tree/iommufd_rfcv4.mig.reset.v4_var3 (requires to test with the cdev kernel) Change log: v8: - Add r-b from Jason to patch 03, 04, 05, 07, 09 of v7 - Add a patch to copy the per-device hot-reset structure to user during the device loop instead of storing them in a buffer and copy all the contents in one copy, this avoids an extra loop to count device and also avoids allocating a temporay buffer for it. (Jason) - Rename vfio_iommufd_device_hot_reset_devid() to be vfio_iommufd_get_dev_id() and refine its return value for the case no valid ID can be returned. Hence make it a general helper to get ID for a device. (Alex, Jason) - Remove iommufd_ctx_has_group() CONIFG_IOMMUFD disabled stub as this API is called in iommufd specific code which is compiled when CONFIG_IOMMU is enabled. (Alex) - Reaffirming Yanting's t-b (Tested NIC passthrough on Intel platform. mainly regression tests) v7: https://lore.kernel.org/kvm/20230602121515.79374-1-yi.l.liu@xxxxxxxxx/ - Drop noiommu support (patch 01 of v6 is dropped) - Remove helpers to get devid and ictx for iommufd_access - Document the dev_set representative requirement in the VFIO_DEVICE_GET_PCI_HOT_RESET_INFO for the cdev opened device (Alex) - zero-length fd array approach is only for cdev opened device (Alex) v6: https://lore.kernel.org/kvm/20230522115751.326947-1-yi.l.liu@xxxxxxxxx/ - Remove noiommu_access, reuse iommufd_access instead (Alex) - vfio_iommufd_physical_ictx -> vfio_iommufd_device_ictx - vfio_iommufd_physical_devid -> vfio_iommufd_device_hot_reset_devid - Refine logic in patch 9 and 10 of v5, no uapi change. (Alex) - Remove lockdep asset in vfio_pci_is_device_in_set (Cédric) - Add t-b from Terrence (Tested GVT-g / GVT-d VFIO legacy mode / compat mode / cdev mode, including negative tests. No regression be introduced.) v5: https://lore.kernel.org/kvm/20230513132136.15021-1-yi.l.liu@xxxxxxxxx/ - Drop patch 01 of v4 (Alex) - Create noiommu_access for noiommu devices (Jason) - Reserve all negative iommufd IDs, hence VFIO can encode negative values (Jason) - Make vfio_iommufd_physical_devid() return -EINVAL if it's not called with a physical device or a noiommu device. - Add vfio_find_device_in_devset() in vfio_main.c (Alex) - Add iommufd_ctx_has_group() to replace vfio_devset_iommufd_has_group(). Reason: vfio_devset_iommufd_has_group() only loops the devices within the given devset to check the iommufd an iommu_group, but an iommu_group can span into multiple devsets. So if failed to find the group in a devset doesn't mean the group is not owned by the iommufd. So here either needs to search all the devsets or add an iommufd API to check it. It appears an iommufd API makes more sense. - Adopt suggestions from Alex on patch 08 and 09 of v4, refine the hot-reset uapi description and minor tweaks - Use bitfields for bool members (Alex) v4: https://lore.kernel.org/kvm/20230426145419.450922-1-yi.l.liu@xxxxxxxxx/ - Rename the patch series subject - Patch 01 is moved from the cdev series - Patch 02, 06 are new per review comments in v3 - Patch 03/04/05/07/08/09 are from v3 with updates v3: https://lore.kernel.org/kvm/20230401144429.88673-1-yi.l.liu@xxxxxxxxx/ - Remove the new _INFO ioctl of v2, extend the existing _INFO ioctl to report devid (Alex) - Add r-b from Jason - Add t-b from Terrence Xu and Yanting Jiang (mainly regression test) v2: https://lore.kernel.org/kvm/20230327093458.44939-1-yi.l.liu@xxxxxxxxx/ - 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@xxxxxxxxx/ Regards, Yi Liu Yi Liu (10): vfio/pci: Update comment around group_fd get in vfio_pci_ioctl_pci_hot_reset() vfio/pci: Move the existing hot reset logic to be a helper iommufd: Reserve all negative IDs in the iommufd xarray iommufd: Add iommufd_ctx_has_group() iommufd: Add helper to retrieve iommufd_ctx and devid vfio: Mark cdev usage in vfio_device vfio: Add helper to search vfio_device in a dev_set vfio/pci: Extend VFIO_DEVICE_GET_PCI_HOT_RESET_INFO for vfio device cdev vfio/pci: Copy hot-reset device info to userspace in the devices loop vfio/pci: Allow passing zero-length fd array in VFIO_DEVICE_PCI_HOT_RESET drivers/iommu/iommufd/device.c | 42 ++++++ drivers/iommu/iommufd/main.c | 2 +- drivers/vfio/iommufd.c | 44 ++++++ drivers/vfio/pci/vfio_pci_core.c | 250 +++++++++++++++++++------------ drivers/vfio/vfio_main.c | 15 ++ include/linux/iommufd.h | 5 + include/linux/vfio.h | 22 +++ include/uapi/linux/vfio.h | 71 ++++++++- 8 files changed, 352 insertions(+), 99 deletions(-) -- 2.34.1
