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
