Re: [PATCH v2 03/19] iommu: Pass in a viommu pointer to domain_alloc_user op

On Tue, Aug 27, 2024 at 09:59:40AM -0700, Nicolin Chen wrote:

With a viommu object wrapping a potentially shareable S2 domain, a nested domain should be allocated by associating to a viommu instead. Driver can store this viommu pointer somewhere, so as to later use it calling viommu helpers for virtual device ID lookup and viommu invalidation.

For drivers without a viommu support, keep the parent domain input, which should be just viommu->hwpt->common.domain otherwise.

I've been thinking of add an op for nested allocation since every driver immediately jumps to a special function for nested allocation anyhow without sharing any code.

Adding a new parameter that is nested only seems like a good point to try to do that..

Jason