ascend inclusion
category: feature
bugzilla: 14369
CVE: NA

--------------

commit https://patchwork.ozlabs.org/patch/822424/

Add bind and unbind operations to the IOMMU API. Device drivers can use
them to share process page tables with their device.
iommu_process_bind_group is provided for VFIO's convenience, as it needs
to provide a coherent interface on containers. Device drivers will most
likely want to use iommu_process_bind_device, which doesn't bind the whole
group.

PASIDs are de facto shared between all devices in a group (because of
hardware weaknesses), but we don't do anything about it at the API level.
Making bind_device call bind_group is probably the wrong way around,
because it requires more work on our side for no benefit. We'd have to
replay all binds each time a device is hotplugged into a group. But when a
device is hotplugged into a group, the device driver will have to do a
bind before using its PASID anyway and we can reject inconsistencies at
that point.

Concurrent calls to iommu_process_bind_device for the same process are not
supported at the moment (they'll race on process_alloc which will only
succeed for the first one; the others will have to retry the bind). I also
don't support calling bind() on a dying process, not sure if it matters.
Signed-off-by: NJean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: NFang Lijun <fanglijun3@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>