On Tue, Oct 17, 2023 at 08:52:49AM +0000, Tian, Kevin wrote:
This is why I wanted to get rid of this bad mechanism going forward.
Manually created hwpt should have a manual specification of cc and then we don't have so many problems.
It means userspace needs to compute if they want to use CC or not, but userspace already needs to figure this out since without autodomains it must create two hwpts manually anyhow.
Now there is no interface reporting enforce_cc to userspace.
Yes..
Actually the user doesn't need to know enforce_cc. As long as there is an attach incompatibility error the user has to create a 2nd hwpt for the to-be-attached device then enforce_cc will be handled automatically in hwpt_alloc.
Uh, OK we can do that.. It is a bit hacky because we don't know the order do
I prefer to removing enforce_cc in attach fn completely then no parent trick in this patch. Just keep it in hwpt_alloc and leave to iommu driver to figure out the attaching compatibility:
You are basically saying to set the cc mode during creation because we know the idev at that moment and can tell if it should be on/off?
It seems reasonable, but I can't remember why it is in the attach path at the moment.
Jason