Hi Felix,
On Tue, Mar 09, 2021 at 11:30:19AM -0500, Felix Kuehling wrote:
> > I think the proper fix would be to not rely on custom hooks into a
> > particular
> > IOMMU driver, but to instead ensure that the amdgpu driver can do everything
> > it needs through the regular linux/iommu.h interfaces. I realize this
> > is more work,
> > but I wonder if you've tried that, and why it didn't work out.
>
> As far as I know this hasn't been tried. I see that intel-iommu has its
> own SVM thing, which seems to be similar to what our IOMMUv2 does. I
> guess we'd have to abstract that into a common API.
The common API was added in 26b25a2b98e4 and implemented by the Intel
driver in 064a57d7ddfc. To support it an IOMMU driver implements new IOMMU
ops:
.dev_has_feat()
.dev_feat_enabled()
.dev_enable_feat()
.dev_disable_feat()
.sva_bind()
.sva_unbind()
.sva_get_pasid()
And a device driver calls iommu_dev_enable_feature(IOMMU_DEV_FEAT_SVA)
followed by iommu_sva_bind_device().
If I remember correctly the biggest obstacle for KFD is the PASID
allocation, done by the GPU driver instead of the IOMMU driver, but there
may be others.
Thanks,
Jean
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