> -----Original Message----- > From: Yi Liu [mailto:yi.l.liu@xxxxxxxxx] > Sent: 14 April 2022 11:47 > To: alex.williamson@xxxxxxxxxx; cohuck@xxxxxxxxxx; > qemu-devel@xxxxxxxxxx > Cc: david@xxxxxxxxxxxxxxxxxxxxx; thuth@xxxxxxxxxx; farman@xxxxxxxxxxxxx; > mjrosato@xxxxxxxxxxxxx; akrowiak@xxxxxxxxxxxxx; pasic@xxxxxxxxxxxxx; > jjherne@xxxxxxxxxxxxx; jasowang@xxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; > jgg@xxxxxxxxxx; nicolinc@xxxxxxxxxx; eric.auger@xxxxxxxxxx; > eric.auger.pro@xxxxxxxxx; kevin.tian@xxxxxxxxx; yi.l.liu@xxxxxxxxx; > chao.p.peng@xxxxxxxxx; yi.y.sun@xxxxxxxxx; peterx@xxxxxxxxxx > Subject: [RFC 00/18] vfio: Adopt iommufd > > With the introduction of iommufd[1], the linux kernel provides a generic > interface for userspace drivers to propagate their DMA mappings to kernel > for assigned devices. This series does the porting of the VFIO devices > onto the /dev/iommu uapi and let it coexist with the legacy implementation. > Other devices like vpda, vfio mdev and etc. are not considered yet. > > For vfio devices, the new interface is tied with device fd and iommufd > as the iommufd solution is device-centric. This is different from legacy > vfio which is group-centric. To support both interfaces in QEMU, this > series introduces the iommu backend concept in the form of different > container classes. The existing vfio container is named legacy container > (equivalent with legacy iommu backend in this series), while the new > iommufd based container is named as iommufd container (may also be > mentioned > as iommufd backend in this series). The two backend types have their own > way to setup secure context and dma management interface. Below diagram > shows how it looks like with both BEs. > > VFIO > AddressSpace/Memory > +-------+ +----------+ +-----+ +-----+ > | pci | | platform | | ap | | ccw | > +---+---+ +----+-----+ +--+--+ +--+--+ +----------------------+ > | | | | | AddressSpace > | > | | | | +------------+---------+ > +---V-----------V-----------V--------V----+ / > | VFIOAddressSpace | <------------+ > | | | MemoryListener > | VFIOContainer list | > +-------+----------------------------+----+ > | | > | | > +-------V------+ +--------V----------+ > | iommufd | | vfio legacy | > | container | | container | > +-------+------+ +--------+----------+ > | | > | /dev/iommu | /dev/vfio/vfio > | /dev/vfio/devices/vfioX | /dev/vfio/$group_id > Userspace | | > > ===========+============================+========================== > ====== > Kernel | device fd | > +---------------+ | group/container fd > | (BIND_IOMMUFD | | > (SET_CONTAINER/SET_IOMMU) > | ATTACH_IOAS) | | device fd > | | | > | +-------V------------V-----------------+ > iommufd | | vfio | > (map/unmap | +---------+--------------------+-------+ > ioas_copy) | | | map/unmap > | | | > +------V------+ +-----V------+ +------V--------+ > | iommfd core | | device | | vfio iommu | > +-------------+ +------------+ +---------------+ > > [Secure Context setup] > - iommufd BE: uses device fd and iommufd to setup secure context > (bind_iommufd, attach_ioas) > - vfio legacy BE: uses group fd and container fd to setup secure context > (set_container, set_iommu) > [Device access] > - iommufd BE: device fd is opened through /dev/vfio/devices/vfioX > - vfio legacy BE: device fd is retrieved from group fd ioctl > [DMA Mapping flow] > - VFIOAddressSpace receives MemoryRegion add/del via MemoryListener > - VFIO populates DMA map/unmap via the container BEs > *) iommufd BE: uses iommufd > *) vfio legacy BE: uses container fd > > This series qomifies the VFIOContainer object which acts as a base class > for a container. This base class is derived into the legacy VFIO container > and the new iommufd based container. The base class implements generic > code > such as code related to memory_listener and address space management > whereas > the derived class implements callbacks that depend on the kernel user space > being used. > > The selection of the backend is made on a device basis using the new > iommufd option (on/off/auto). By default the iommufd backend is selected > if supported by the host and by QEMU (iommufd KConfig). This option is > currently available only for the vfio-pci device. For other types of > devices, it does not yet exist and the legacy BE is chosen by default. > > Test done: > - PCI and Platform device were tested > - ccw and ap were only compile-tested > - limited device hotplug test > - vIOMMU test run for both legacy and iommufd backends (limited tests) > > This series was co-developed by Eric Auger and me based on the exploration > iommufd kernel[2], complete code of this series is available in[3]. As > iommufd kernel is in the early step (only iommufd generic interface is in > mailing list), so this series hasn't made the iommufd backend fully on par > with legacy backend w.r.t. features like p2p mappings, coherency tracking, > live migration, etc. This series hasn't supported PCI devices without FLR > neither as the kernel doesn't support VFIO_DEVICE_PCI_HOT_RESET when > userspace > is using iommufd. The kernel needs to be updated to accept device fd list for > reset when userspace is using iommufd. Related work is in progress by > Jason[4]. > > TODOs: > - Add DMA alias check for iommufd BE (group level) > - Make pci.c to be BE agnostic. Needs kernel change as well to fix the > VFIO_DEVICE_PCI_HOT_RESET gap > - Cleanup the VFIODevice fields as it's used in both BEs > - Add locks > - Replace list with g_tree > - More tests > > Patch Overview: > > - Preparation: > 0001-scripts-update-linux-headers-Add-iommufd.h.patch > 0002-linux-headers-Import-latest-vfio.h-and-iommufd.h.patch > 0003-hw-vfio-pci-fix-vfio_pci_hot_reset_result-trace-poin.patch > 0004-vfio-pci-Use-vbasedev-local-variable-in-vfio_realize.patch > > 0005-vfio-common-Rename-VFIOGuestIOMMU-iommu-into-iommu_m.patch > 0006-vfio-common-Split-common.c-into-common.c-container.c.patch > > - Introduce container object and covert existing vfio to use it: > 0007-vfio-Add-base-object-for-VFIOContainer.patch > 0008-vfio-container-Introduce-vfio_attach-detach_device.patch > 0009-vfio-platform-Use-vfio_-attach-detach-_device.patch > 0010-vfio-ap-Use-vfio_-attach-detach-_device.patch > 0011-vfio-ccw-Use-vfio_-attach-detach-_device.patch > 0012-vfio-container-obj-Introduce-attach-detach-_device-c.patch > 0013-vfio-container-obj-Introduce-VFIOContainer-reset-cal.patch > > - Introduce iommufd based container: > 0014-hw-iommufd-Creation.patch > 0015-vfio-iommufd-Implement-iommufd-backend.patch > 0016-vfio-iommufd-Add-IOAS_COPY_DMA-support.patch > > - Add backend selection for vfio-pci: > 0017-vfio-as-Allow-the-selection-of-a-given-iommu-backend.patch > 0018-vfio-pci-Add-an-iommufd-option.patch > > [1] > https://lore.kernel.org/kvm/0-v1-e79cd8d168e8+6-iommufd_jgg@xxxxxxxxxx > / > [2] https://github.com/luxis1999/iommufd/tree/iommufd-v5.17-rc6 > [3] https://github.com/luxis1999/qemu/tree/qemu-for-5.17-rc6-vm-rfcv1 Hi, I had a go with the above branches on our ARM64 platform trying to pass-through a VF dev, but Qemu reports an error as below, [ 0.444728] hisi_sec2 0000:00:01.0: enabling device (0000 -> 0002) qemu-system-aarch64-iommufd: IOMMU_IOAS_MAP failed: Bad address qemu-system-aarch64-iommufd: vfio_container_dma_map(0xaaaafeb40ce0, 0x8000000000, 0x10000, 0xffffb40ef000) = -14 (Bad address) I think this happens for the dev BAR addr range. I haven't debugged the kernel yet to see where it actually reports that. Maybe I am missing something. Please let me know. Thanks, Shameer
