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?
https://lore.kernel.org/linux-iommu/ZxsSYbK3gqyC84U7@Asurada-Nvidia/ https://lore.kernel.org/linux-iommu/ZxsTAANTTuQzQ9HR@Asurada-Nvidia/
Do you need vdevice_alloc in the driver for your sketch?
At the moment one of the things I am looking for is a place to add tsm_bind(host_bdfn, guest_bdfn, kvm_vmid). I assumed that this vdevice represents the guest's IOMMU attributes for a passed through device and naturally stores the guest_bdfn as an id (for AMD). I am still trying to wrap my head around these new things. Thanks,