On Mon, Aug 19, 2024 at 11:38:22AM -0700, Nicolin Chen wrote:
On Mon, Aug 19, 2024 at 03:28:11PM -0300, Jason Gunthorpe wrote:
On Mon, Aug 19, 2024 at 11:19:39AM -0700, Nicolin Chen wrote:
But nesting enablment with out viommu is alot less useful than I had thought :(
Actually, without viommu, the hwpt cache invalidate alone could still support non-SVA case?
That is what I thought, but doesn't the guest still have to invalidate the CD table entry # 0?
I recall it doesn't. The CD cache invalidation is required in the viommu invalidation for an SVA case where we need a PASID number to specify CD to the substream. But the CD to the default stream is only changed during a vSTE setup, and the host knows the PASID number (=0)?
I think that would subtly assume certain things about how the driver does ordering, ie the that CD table entry 0 is setup with the S1 before we load it into the STE.
Yes, the Linux driver does that now, but I don't think anyone should rely on that..
Jason