Questions regarding the still unpublished qemu series https://github.com/yiliu1765/qemu/tree/zhenzhong/wip/iommufd_nesting_rfcv1

[Joel Granados]

Hello Everyone

While running 
https://github.com/yiliu1765/qemu/tree/zhenzhong/wip/iommufd_nesting_rfcv1
I have come across particular code path that seems odd:

I'm hitting an assert in softmmu/memory.c:1994 after calling a
notification from vtd_flt_page_walk_level. The code in memory.c:1994
makes sure that when type==IOMMU_NOTIFIER_UNMAP, the permissions are
IOMMU_NONE. But the code in vtd_flt_page_walk_level sets the
permissions to read|write. This is part of the "intel_iommu: piotlb
invalidation should notify unmap" commit in the iommufd_nesting_rfcv1
series.

Question is: Why assert on the permissions being NONE if they might be
read|write?

Hope this makes sense. Don't hesitate to get back to me if you see that
there is something missing in my explanation.

Best

-- 

Joel Granados

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