RE: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation APIs

Liu, Yi L
2021-04-01T13:38:58Z

> From: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Sent: Thursday, April 1, 2021 8:05 PM
[...]
>
> Also wondering about:
>
> * Querying IOMMU nesting capabilities before binding page tables (which
> page table formats are supported?). We were planning to have a VFIO cap,
> but I'm guessing we need to go back to the sysfs solution?

I think it can also be with /dev/ioasid.

>
> * Invalidation, probably an ioasid_fd ioctl?

yeah, if we are doing bind/unbind_pagtable via ioasid_fd, then yes,
invalidation should go this way as well. This is why I worried it may
fail to meet the requirement from you and Eric.

> * Page faults, page response. From and to devices, and don't necessarily
> have a PASID. But needed by vdpa as well, so that's also going through
> /dev/ioasid?

page faults should still be per-device, but the fault event fd may be stored
in /dev/ioasid. page response would be in /dev/ioasid just like invalidation.

Regards,
Yi Liu

>
> Thanks,
> Jean