On Fri, Oct 25, 2024 at 04:32:10PM +1100, Alexey Kardashevskiy wrote: > External email: Use caution opening links or attachments > > > On 25/10/24 15:59, Nicolin Chen wrote: > > On Fri, Oct 25, 2024 at 03:54:44PM +1100, Alexey Kardashevskiy wrote: > > > On 22/10/24 11:20, Nicolin Chen wrote: > > > > Following the previous vIOMMU series, this adds another vDEVICE > > > > structure, > > > > representing the association from an iommufd_device to an > > > > iommufd_viommu. > > > > This gives the whole architecture a new "v" layer: > > > > > > > > _______________________________________________________________________ > > > > | iommufd (with vIOMMU/vDEVICE) > > > > | > > > > | _____________ _____________ > > > > | > > > > | | | | | > > > > | > > > > | |----------------| vIOMMU |<---| vDEVICE |<------| > > > > | > > > > | | | | |_____________| | > > > > | > > > > | | ______ | | _____________ > > > > ___|____ | > > > > | | | | | | | | | > > > > | | > > > > | | | IOAS |<---|(HWPT_PAGING)|<---| HWPT_NESTED |<--| > > > > DEVICE | | > > > > | | |______| |_____________| |_____________| > > > > |________| | > > > > > > > > |______|________|______________|__________________|_______________|_____| > > > > | | | | | > > > > ______v_____ | ______v_____ ______v_____ ___v__ > > > > | struct | | PFN | (paging) | | (nested) | > > > > |struct| > > > > |iommu_device| > > > > |------>|iommu_domain|<----|iommu_domain|<----|device| > > > > |____________| storage|____________| |____________| > > > > |______| > > > > > > > > This vDEVICE object is used to collect and store all vIOMMU-related > > > > device > > > > information/attributes in a VM. As an initial series for vDEVICE, add > > > > only > > > > the virt_id to the vDEVICE, which is a vIOMMU specific device ID in a > > > > VM: > > > > e.g. vSID of ARM SMMUv3, vDeviceID of AMD IOMMU, and vID of Intel VT-d > > > > to > > > > a Context Table. This virt_id helps IOMMU drivers to link the vID to a > > > > pID > > > > of the device against the physical IOMMU instance. This is essential > > > > for a > > > > vIOMMU-based invalidation, where the request contains a device's vID > > > > for a > > > > device cache flush, e.g. ATC invalidation. > > > > > > > > Therefore, with this vDEVICE object, support a vIOMMU-based > > > > invalidation, > > > > by reusing IOMMUFD_CMD_HWPT_INVALIDATE for a vIOMMU object to flush > > > > cache > > > > with a given driver data. > > > > > > > > As for the implementation of the series, add driver support in ARM > > > > SMMUv3 > > > > for a real world use case. > > > > > > > > This series is on Github: > > > > https://github.com/nicolinc/iommufd/commits/iommufd_viommu_p2-v4 > > > > > > > > For testing, try this "with-rmr" branch: > > > > https://github.com/nicolinc/iommufd/commits/iommufd_viommu_p2-v4-with-rmr > > > > > > Is there any real example of a .vdevice_alloc hook, besides the > > > selftests? It is not in iommufd_viommu_p2-v4-with-rmr, hence the > > > question. I am trying to sketch something with this new machinery and > > > less guessing would be nice. Thanks, > > > > No, I am actually dropping that one, and moving the vdevice struct > > to the private header, as there seems to be no use case: > > Why keep it then?
We need that structure to store per-vIOMMU virtual ID. Hiding it in the core only means we need to provide another vIOMMU APIs for drivers to look up the ID, v.s. exposing it for drivers to access directly. Thanks Nicolin
