[Xen-devel] [PATCH] VT-d: per-iommu domain-id

["Han, Weidong" <weidong.han@xxxxxxxxx>]

Currently, xen uses shared iommu domain-id across all the VT-d units in the 
platform. The number of iommu domain-ids (NR_DID, e.g. 256) supported by each 
VT-d unit is reported in Capability register. The limitation of current 
implementation is it only can support at most NR_DID domains with VT-d in the 
entire platform, even though the platform can support N * NR_DID (where N is 
the number of VT-d units). Imagine a platform with several SR_IOV NICs, and 
each NIC supports 128 VFs. It possibly beyond the NR_DID. 

This patch implements iommu domain-id management per iommu (VT-d unit), hence 
solves above limitation. It removes the global domain-id bitmap, instead use 
domain-id bitmap in struct iommu, and also involve an array to map guest 
domain-id and iommu domain-id, which is used to iommu domain-id when flush 
context cache or IOTLB. When a device is assigned to a guest, choose an 
available iommu domain-id from the device's iommu, and map guest domain id to 
the domain-id mapping array. When a device is deassigned from a guest, clear 
the domain-id bit in domain-id bitmap and clear the corresponding entry in 
domain-id map array if there is no other devices under the same iommu owned by 
the guest.

Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>

Attachment: per-iommu-domid.patch
Description: per-iommu-domid.patch

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