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

On Thu, Sep 05, 2024 at 12:54:54PM -0300, Jason Gunthorpe wrote:

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

quoted

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..

Yea, it makes sense to have a domain_alloc_nested, for hwpt_nested
exclusively. Then domain_alloc_user would be for hwpt_paging only.

Thanks
Nicolin