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From:   "Liu, Yi L" <yi.l.liu@intel.com>
To:     Jean-Philippe Brucker <jean-philippe@linaro.org>
CC:     Jason Gunthorpe <jgg@nvidia.com>,
        "Tian, Kevin" <kevin.tian@intel.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
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        "Raj, Ashok" <ashok.raj@intel.com>, "Wu, Hao" <hao.wu@intel.com>,
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Subject: RE: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation
 APIs
Thread-Topic: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and
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Date:   Thu, 1 Apr 2021 13:38:46 +0000
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> From: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Sent: Thursday, April 1, 2021 8:05 PM
[...]
>=20
> Also wondering about:
>=20
> * 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.

>=20
> * 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 store=
d
in /dev/ioasid. page response would be in /dev/ioasid just like invalidatio=
n.

Regards,
Yi Liu

>=20
> Thanks,
> Jean