If we do it, the upper layer still needs to query the capability from domain and switchIf that's the case, why not putting this logic in the iommu subsystem soI suppose this interface is to ask the vendor IOMMU driver to checkYep, this is considered in the vfio part. We will query again after attaching or
whether each device/iommu in the domain supports dirty bit tracking.
But what will happen if new devices with different tracking capability
are added afterward?
detaching devices from the domain. When the domain becomes capable, we enable
dirty log for it. When it becomes not capable, we disable dirty log for it.
that it doesn't need to be duplicate in different upper layers?
For example, add something like dirty_page_trackable in the struct of
iommu_domain and ask the vendor iommu driver to update it once any
device is added/removed to/from the domain. It's also better to disallow
dirty log tracking for it. Or do you mean the domain can switch dirty log tracking automatically
when its capability change? If so, I think we're lack of some flexibility. The upper layer
may have it's own policy, such as only enable dirty log tracking when all domains are capable,
and disable dirty log tracking when just one domain is not capable.
any domain attach/detach once the dirty page tracking is on.Yep, this can greatly simplify our code logic, but I don't know whether our maintainers
agree that, as they may think that IOMMU dirty logging should not change original domain