Hi Jason,

On 4/29/21 10:04 PM, Jason Gunthorpe wrote:

On Thu, Apr 29, 2021 at 03:26:55PM +0200, Auger Eric wrote:

quoted

From the pseudo code,

  gpa_ioasid_id = ioctl(ioasid_fd, CREATE_IOASID, ..)
  ioctl(ioasid_fd, SET_IOASID_PAGE_TABLES, ..)

I fail to understand whether the SET_IOASID_PAGE_TABLES would apply to
the whole IOASIDs within /dev/ioasid or to a specific one.

Sorry, nearly every IOCTL would be scoped to a specific IOASID as one
of the arguments.

OK thank you for the clarification.

quoted

Also in subsequent emails when you talk about IOASID, is it the
ioasid_id, just to double check the terminology.

I am refering to IOASID as 'handle of the page table object inside the
/dev/ioasid fd'. If that is equal to some HW value or not I think
remains as decision point.

OK

Basically the fd has an xarray of 'struct [something] *' and the
IOASID is index to that FD's private xarray. This is necessary to
create proper security as even if we have global PASID numbers or
something they still need to be isolated to only the FD that has
been authorized access.

quoted

quoted

  nested_ioasid = ioctl(ioasid_fd, CREATE_NESTED_IOASID,  gpa_ioasid_id);
  ioctl(ioasid_fd, SET_NESTED_IOASID_PAGE_TABLES, nested_ioasid, ..)

is the nested_ioasid the allocated PASID id or is it a complete
different object id.

It is the IOASID handle above.

ok as per the following emails and below comment IOASID and PASID are
different.The first would be a logic ID wgile the second the HW ID.

Thanks

Eric

quoted

quoted

   // IOMMU will match on the device RID, no PASID:
  ioctl(vfio_device, ATTACH_IOASID, nested_ioasid);

   // IOMMU will match on the device RID and PASID:
  ioctl(vfio_device, ATTACH_IOASID_PASID, pasid, nested_ioasid);

here I see you pass a different pasid, so I guess they are different, in
which case you would need to have an allocator function for this pasid,
right?

Yes, the underlying HW ID (PASID or substream id or whatver) is
something slightly different

Jason