[Intel-gfx] [PATCH v1 1/5] iommufd: Create access in vfio_iommufd_emulated_bind()

Wed Mar 15 12:18:01 UTC 2023

> From: Nicolin Chen <nicolinc at nvidia.com>
> Sent: Wednesday, March 15, 2023 5:03 PM
> 
> Hi,
> 
> On Wed, Mar 15, 2023 at 06:50:53AM +0000, Tian, Kevin wrote:
> 
> > > So, this preparatory series will add a pair of simple attach()
> > > and detach() APIs. Then the cdev series will add the locking
> > > and the ioas_unpin stuff as a rework of the detach() API.
> 
> > > I think they can be something mingled... the sample code that
> > > I sent previously could take care of those conditions. But, I
> > > am also thinking a bit that maybe attach() does not need the
> > > locking? I can do a separate replace() function in this case.
> > >
> >
> > w/o locking then you need smp_store_release() and its pair.
> >
> > anyway it's not in perf critical path. Keeping lock for attach
> > is simpler and safe.
> 
> OK. Basically I followed what Jason suggested by having three
> APIs and combined Kevin's inputs about the difference between
> the attach/replace(). I also updated the replace changes, and
> rebased all nesting (infrastructure, VT-d and SMMU):
> https://github.com/nicolinc/iommufd/commits/wip/iommufd_nesting-03142023
> 
> The major three changes for those APIs:
> [1] This adds iommufd_access_attach() in this series:
>     "iommufd: Create access in vfio_iommufd_emulated_bind()"
> 
> https://github.com/nicolinc/iommufd/commit/34fba7509429380f828fb23dc
> ca5ceaeb40e22b5
> [2] This adds iommufd_access_detach() in the cdev series:
>     "iommufd/device: Add iommufd_access_detach() API"
> 
> https://github.com/nicolinc/iommufd/commit/4110522146ca1fc0d5321c04a
> 097e2c9d9e26af4
> [3] This adds iommufd_access_replace() in the replace series:
>     "iommufd: Add iommufd_access_replace() API"
> 
> https://github.com/nicolinc/iommufd/commit/36507fa9f0f42cf1a5bebe7c9
> bc2bf319b7654a8
> 
> Please check if they look okay, so that Yi can integrate them
> accordingly to the emulated/cdev series.

Thanks. I'll start to integrate after ack from Kevin or Jason. btw.
Below is my latest code (rebased on top of rc-2). 😊

https://github.com/yiliu1765/iommufd/tree/wip/vfio_device_cdev_v7_candidate

> 
> [*] This is the patch that I posted in the other mail addressing
>     Kevin's comments on iommufd_ctx_get():
>     "iommufd/device: Do iommufd_ctx_get() at the top of
> iommufd_access_create()"
> 
> https://github.com/nicolinc/iommufd/commit/077b09bb83329dc046753f4ef
> 672f5bf6386755c
>     (I just saw Yi's reply concerning its necessity. Feel free
>      to drop in that case.)

Yeah, let's see Kevin's feedback.

> 
> Thanks
> Nicolin
> 
> P.S. Attaching the list of changes with their locations:
> 3791dedf98e8 cover-letter: Add IO page table replacement support
> c8ebf51c3c9b vfio: Support IO page table replacement
> c5710f23e8f6 iommufd/selftest: Add
> IOMMU_TEST_OP_ACCESS_REPLACE_IOAS coverage
> [3] 36507fa9f0f4 iommufd: Add iommufd_access_replace() API
> 0263855d1e8b vfio: Do not allow !ops->dma_unmap in
> vfio_pin/unpin_pages()
> e39ed55e77a0 cover-letter: Add vfio_device cdev for iommufd support
> 26fd7fccaef3 docs: vfio: Add vfio device cdev description
> f10f3e3162bb vfio: Compile group optionally
> 9588ae4c4049 vfio: Add VFIO_DEVICE_AT[DE]TACH_IOMMUFD_PT
> 3e57108eac64 vfio: Add VFIO_DEVICE_BIND_IOMMUFD
> b925716dd226 vfio: Add cdev for vfio_device
> db309463ab92 vfio-iommufd: Add detach_ioas support for emulated VFIO
> devices
> [2] 4110522146ca iommufd/device: Add iommufd_access_detach() API
> abca7e1e063a vfio-iommufd: Add detach_ioas support for physical VFIO
> devices
> 9d368f7247c7 vfio: Record devid in vfio_device_file
> 683af0a471e1 vfio-iommufd: Split the compat_ioas attach out from
> vfio_iommufd_bind()
> 32a2e7de1d53 vfio-iommufd: Split the no-iommu support out from
> vfio_iommufd_bind()
> 8a1c042379f5 vfio: Make vfio_device_first_open() to accept NULL iommufd
> for noiommu
> fc6e0ed2aa44 vfio: Make vfio_device_open() single open for device cdev
> path
> 3f6821d507a4 vfio: Add cdev_device_open_cnt to vfio_group
> 896cde40a016 vfio: Block device access via device fd until device is opened
> f422c4216a19 vfio: Pass struct vfio_device_file * to vfio_device_open/close()
> b187f9980fed kvm/vfio: Accept vfio device file from userspace
> 721e2e60ff54 kvm/vfio: Rename kvm_vfio_group to prepare for accepting
> vfio device fd
> 8993c4c75c20 vfio: Accept vfio device file in the KVM facing kAPI
> a92c45ae0ce6 vfio: Remove vfio_file_is_group()
> fb586f783934 vfio: Refine vfio file kAPIs for KVM
> 50694af6f3c0 vfio: Allocate per device file structure
> df21c0737eef cover-letter: Make vfio-pci hot reset prepared for vfio device
> cdev
> 5c25c874d7e0 vfio/pci: Accept device fd in VFIO_DEVICE_PCI_HOT_RESET
> ioctl
> 7c30ce8b54db vfio: Accpet device file from vfio PCI hot reset path
> e3209342db44 vfio: Refine vfio file kAPIs for vfio PCI hot reset
> 8354fd79944e vfio/pci: Rename the helpers and data in hot reset path to
> accept device fd
> 54387efb858c vfio/pci: Allow passing zero-length fd array in
> VFIO_DEVICE_PCI_HOT_RESET
> cd93ffb62c51 vfio/pci: Only need to check opened devices in the dev_set
> for hot reset
> 2a6fd7231cbf vfio/pci: Update comment around group_fd get in
> vfio_pci_ioctl_pci_hot_reset()
> 480abea5961e cover-letter: vfio: Make emulated devices prepared for vfio
> device cdev
> 46b6d1ae1754 vfio: Check the presence for iommufd callbacks in
> __vfio_register_dev()
> 6064b9f81817 Samples/mdev: Uses the vfio emulated iommufd ops set in
> the mdev sample drivers
> c20852af7291 vfio-iommufd: Make vfio_iommufd_emulated_bind() return
> iommufd_access ID
> 3405865b0b3f vfio-iommufd: No need to record iommufd_ctx in vfio_device
> [*] 077b09bb8332 iommufd/device: Do iommufd_ctx_get() at the top of
> iommufd_access_create()
> [1] 34fba7509429 iommufd: Create access in vfio_iommufd_emulated_bind()
> a5d8ac47554f docs: kvm: vfio: Require call KVM_DEV_VFIO_GROUP_ADD
> before VFIO_GROUP_GET_DEVICE_FD