On 2021/5/19 2:58, Alex Williamson wrote: > On Fri, 9 Apr 2021 11:44:19 +0800 > Shenming Lu <lushenming@xxxxxxxxxx> wrote: > >> Some devices only allow selective DMA faulting. Similar to the selective >> dirty page tracking, the vendor driver can call vfio_pin_pages() to >> indicate the non-faultable scope, we add a new struct vfio_range to >> record it, then when the IOPF handler receives any page request out >> of the scope, we can directly return with an invalid response. > > Seems like this highlights a deficiency in the design, that the user > can't specify mappings as iopf enabled or disabled. Also, if the > vendor driver has pinned pages within the range, shouldn't that prevent > them from faulting in the first place? Why do we need yet more > tracking structures? Pages pinned by the vendor driver need to count > against the user's locked memory limits regardless of iopf. Thanks, Currently we only have a vfio_pfn struct to track the external pinned pages (single page granularity), so I add a vfio_range struct for efficient lookup. Yeah, by this patch, for the non-pinned scope, we can directly return INVALID, but for the pinned(non-faultable) scope, tracking the pinned range doesn't seem to help more... Thanks, Shenming > > Alex > > . >
