在 2021/6/2 上午4:28, Jason Gunthorpe 写道:
I summarized five opens here, about:
1) Finalizing the name to replace /dev/ioasid;
2) Whether one device is allowed to bind to multiple IOASID fd's;
3) Carry device information in invalidation/fault reporting uAPI;
4) What should/could be specified when allocating an IOASID;
5) The protocol between vfio group and kvm;
For 1), two alternative names are mentioned: /dev/iommu and
/dev/ioas. I don't have a strong preference and would like to hear
votes from all stakeholders. /dev/iommu is slightly better imho for
two reasons. First, per AMD's presentation in last KVM forum they
implement vIOMMU in hardware thus need to support user-managed
domains. An iommu uAPI notation might make more sense moving
forward. Second, it makes later uAPI naming easier as 'IOASID' can
be always put as an object, e.g. IOMMU_ALLOC_IOASID instead of
IOASID_ALLOC_IOASID.:)
I think two years ago I suggested /dev/iommu and it didn't go very far
at the time.
It looks to me using "/dev/iommu" excludes the possibility of
implementing IOASID in a device specific way (e.g through the
co-operation with device MMU + platform IOMMU)?
What's more, ATS spec doesn't forbid the device #PF to be reported via a
device specific way.
Thanks
We've also talked about this as /dev/sva for a while and
now /dev/ioasid
I think /dev/iommu is fine, and call the things inside them IOAS
objects.
Then we don't have naming aliasing with kernel constructs.
