On Wed, Jan 26, 2022 at 09:51:36AM +0800, Lu Baolu wrote:
they are fundamentally different things in their own right, and the ideal
API should give us the orthogonality to also bind a device to an SVA domain
without PASID (e.g. for KVM stage 2, or userspace assignment of simpler
fault/stall-tolerant devices), or attach PASIDs to regular iommu_domains.
Yes, these are orthogonal things. A iommu driver that supports PASID
ideally should support PASID enabled attach/detatch for every
iommu_domain type it supports.
SVA should not be entangled with PASID beyond that SVA is often used
with PASID - a SVA iommu_domain should be fully usable with a RID too.
The prototype of PASID enabled attach/detach ops could look like:
int (*attach_dev_pasid)(struct iommu_domain *domain,
struct device *dev, ioasid_t id);
void (*detach_dev_pasid)(struct iommu_domain *domain,
struct device *dev, ioasid_t id);
It seems reasonable and straightforward to me..
These would be domain ops?
But the iommu driver should implement different callbacks for
1) attaching an IOMMU DMA domain to a PASID on device;
- kernel DMA with PASID
- mdev-like device passthrough
- etc.
2) attaching a CPU-shared domain to a PASID on device;
- SVA
- guest PASID
- etc.
But this you mean domain->ops would be different? Seems fine, up to
the driver.
I'd hope to see some flow like:
domain = device->bus->iommu_ops->alloc_sva_domain(dev)
domain->ops->attach_dev_pasid(domain, dev, current->pasid)
To duplicate the current SVA APIs