Re: [PATCH RFC v3 04/12] iommu/sva: Basic data structures for SVA

From: Lu Baolu
Date: Tue Apr 12 2022 - 08:38:55 EST


On 2022/4/12 14:49, Tian, Kevin wrote:
From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Sent: Sunday, April 10, 2022 6:25 PM

Use below data structures for SVA implementation in the IOMMU core:

- struct iommu_sva_ioas
Represent the I/O address space shared with an application CPU address
space. This structure has a 1:1 relationship with an mm_struct. It
graps a "mm->mm_count" refcount during creation and drop it on release.

- struct iommu_domain (IOMMU_DOMAIN_SVA type)
Represent a hardware pagetable that the IOMMU hardware could use for
SVA translation. Multiple iommu domains could be bound with an SVA ioas
and each graps a refcount from ioas in order to make sure ioas could
only be freed after all domains have been unbound.

- struct iommu_sva
Represent a bond relationship between an SVA ioas and an iommu domain.
If a bond already exists, it's reused and a reference is taken.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

This should be patch07. None of following patches touch those structures
until hitting patch08.

The iommu_sva_domain_mm() helper will be used in the following patches.

Best regards,
baolu