[vfio-users] VM doesn't boot, hangs with R9 Fury passthrough

[Alex Williamson]

On Wed, Sep 2, 2015 at 11:22 AM, Matti Niemenmaa <
matti.niemenmaa+vfio at iki.fi> wrote:

>
> The source code line pointed to is the WARN_ON in the following snippet in
> vfio_unmap_unpin (presumably inlined into vfio_remove_dma, which is why
> only that shows in the trace):
>
>                 phys = iommu_iova_to_phys(domain->domain, iova);
>                 if (WARN_ON(!phys)) {
>                         iova += PAGE_SIZE;
>                         continue;
>                 }
>
> As I'm lacking the required low-level knowledge I'll once again simply say
> that any assistance would be welcomed. I'm glad I made at least some
> progress, though. :-)


The vfio IOMMU code is being asked to unmap an I/O virtual address (IOVA)
that was never mapped, which should never happen.  Something is pretty
broken in the VM or IOMMU if this happens.
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