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vtblk: Bypass iommu on powerpc
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Authored by cperciva on Dec 28 2022, 6:32 AM.
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Details

Summary

Virtio operates with physical addresses, while busdma is designed to
map these to produce bus addresses. On most supported platforms,
these two are interchangeable; on powerpc platforms, they are not.

When on powerpc, set an IOMMU of NULL, which causes the powerpc busdma
code to bypass the iommu mapping; this leaves us with the physical
buffer addresses which the virtio host expects to see.

Fixes: 782105f7c898 ("vtblk: Use busdma")

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I verified the patch on powerpc64, powerpc64le and it fixes the issue completely. Also, powerpc 32 bit is fine with this patch.

Thank you @cperciva !

This revision is now accepted and ready to land.Jan 11 2023, 3:35 AM
This revision was automatically updated to reflect the committed changes.