Re: [PATCH RFC 00/19] IOMMUFD Dirty Tracking

Jason Gunthorpe
2022-05-10T14:18:56Z

On Tue, May 10, 2022 at 01:38:26AM +0000, Tian, Kevin wrote:

> > However, tt costs nothing to have dirty tracking as long as all iommus
> > support it in the system - which seems to be the normal case today.
> >
> > We should just always turn it on at this point.
>
> Then still need a way to report " all iommus support it in the system"
> to userspace since many old systems don't support it at all.

Userspace can query the iommu_domain directly, or 'try and fail' to
turn on tracking.

A device capability flag is useless without a control knob to request
a domain is created with tracking, and we don't have that, or a reason
to add that.

Jason