On Thu, Feb 02, 2017 at 04:40:49PM +0000, Will Deacon wrote:

On Thu, Feb 02, 2017 at 06:30:28PM +0200, Michael S. Tsirkin wrote:

quoted

I am inclined to say, for 4.10 let's revert
c7070619f3408d9a0dffbed9149e6f00479cf43b since what it fixes is not a
regression in 4.10.

No complaints there, as long as we can keep working to fix this for 4.11
and onwards. You'll also need to cc stable on the revert.

quoted

So I think we can defer the fix to 4.11.
I think we still want f7f6634d23830ff74335734fbdb28ea109c1f349
for hosts with virtio 1 support.

All this will hopefully push hosts to just implement virtio 1.
For mmio the changes are very small: several new registers,
that's all. You want this for proper 64 bit dma mask anyway.

As I've said, virtio 1 will have exactly the same issue unless we start
requiring firmware to advertise dma-coherent/_CCA for virtio-mmio
devices correctly.

Will

I mostly agree with that, just didn't have time to read up on _CCA yet.

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MST