Hey Lu, > On 9 Mar 2019, at 01:53, Lu Baolu <baolu...@linux.intel.com> wrote: > > Hi James, > > On 3/9/19 12:57 AM, James Sewart wrote: >> Hey Lu, >>> On 8 Mar 2019, at 03:09, Lu Baolu<baolu...@linux.intel.com> wrote: >>>>> >>>>> Do you mind if I work on top of your patches for further cleanups and >>>>> sign off a v2 together with you? >>>> Sure, sounds good. I’ll fixup patch 3 and have a go at integrating >>>> iommu_prepare_isa into get_resv_regions. This should make the initial >>>> domain logic here quite concise. >>> Here attached three extra patches which I think should be added before >>> PATCH 3/4, and some further cleanup changes which you can merge with >>> PATCH 4/4. >>> >>> ---------------- >>> >>> 0006-iommu-Add-ops-entry-for-vendor-specific-default-doma.patch >>> 0007-iommu-vt-d-Add-is_identity_map-ops-entry.patch >>> >>> These two patches aim to add a generic method for vendor specific iommu >>> drivers to specify the type of the default domain for a device. Intel >>> iommu driver will register an ops for this since it already has its own >>> identity map adjudicator for a long time. >> This seems like a good idea, but as domain alloc is only called for the >> default domain on first device attached to a group, we may miss checking >> whether a device added later should have an identity domain. Should there >> be paths to downgrade a groups domain if one of the devices requires one? > > Good catch! > > This is supposed to be handled in iommu_no_mapping(). But, obviously > current code sticks to lazy domain allocation. I'm not sure whether > there are any real such cases, but we should handle it in a clean way. > My idea is that we could downgrade to multiple domains per group (just > like what we have now) in this case and print a kernel message for this.
I think if a device requires an identity domain, then it should ignore attempts to attach to something else. A print to warn a user about this would be a good idea. I figure during attach: if iommu_no_mapping() then attach to si_domain and print, else continue with the given domain. > > Or any other thoughts? > > Best regards, > Lu Baolu Cheers, James.
