On Tue, 2020-03-31 at 01:23:38 UTC, Alexey Kardashevskiy wrote:

Unlike normal memory ("memory" compatible type in the FDT),
the persistent memory ("ibm,pmemory" in the FDT) can be mapped anywhere
in the guest physical space and it can be used for DMA.

In order to maintain 1:1 mapping via the huge DMA window, we need to
know the maximum physical address at the time of the window setup.
So far we've been looking at "memory" nodes but "ibm,pmemory" does not
have fixed addresses and the persistent memory may be mapped afterwards.

Since the persistent memory is still backed with page structs,
use MAX_PHYSMEM_BITS as the upper limit.

This effectively disables huge DMA window in LPAR under pHyp if
persistent memory is present but this is the best we can do.

Signed-off-by: Alexey Kardashevskiy <redacted>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/54fc3c681ded9437e4548e2501dc1136b23cfa9a

cheers