Will Deacon [off-list ref] writes:

Commit ad6c00283163 ("swiotlb: Free tbl memory in swiotlb_exit()")
introduced a set_memory_encrypted() call to swiotlb_exit() so that the
buffer pages are returned to an encrypted state prior to being freed.

Sachin reports that this leads to the following crash on a Power server:

[    0.010799] software IO TLB: tearing down default memory pool
[    0.010805] ------------[ cut here ]------------
[    0.010808] kernel BUG at arch/powerpc/kernel/interrupt.c:98!

Nick spotted that this is because set_memory_encrypted() is issuing an
ultracall which doesn't exist for the processor, and should therefore
be gated by mem_encrypt_active() to mirror the x86 implementation.

Cc: Konrad Rzeszutek Wilk <redacted>
Cc: Claire Chang <redacted>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Fixes: ad6c00283163 ("swiotlb: Free tbl memory in swiotlb_exit()")
Suggested-by: Nicholas Piggin <npiggin@gmail.com>
Reported-by: Sachin Sant <redacted>
Tested-by: Sachin Sant <redacted>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/1905CD70-7656-42AE-99E2-A31FC3812EAC@linux.vnet.ibm.com/ (local)
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/powerpc/platforms/pseries/svm.c | 6 ++++++
 1 file changed, 6 insertions(+)

Thanks.

Acked-by: Michael Ellerman <mpe@ellerman.id.au>


I assume Konrad will take this via the swiotlb tree?

cheers