Re: [PATCH] powerpc/svm: Don't issue ultracalls if !mem_encrypt_active()

[Michael Ellerman]

Will Deacon <will@xxxxxxxxxx> 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 <konrad.wilk@xxxxxxxxxx>
> Cc: Claire Chang <tientzu@xxxxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Robin Murphy <robin.murphy@xxxxxxx>
> Fixes: ad6c00283163 ("swiotlb: Free tbl memory in swiotlb_exit()")
> Suggested-by: Nicholas Piggin <npiggin@xxxxxxxxx>
> Reported-by: Sachin Sant <sachinp@xxxxxxxxxxxxxxxxxx>
> Tested-by: Sachin Sant <sachinp@xxxxxxxxxxxxxxxxxx>
> Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/1905CD70-7656-42AE-99E2-A31FC3812EAC@xxxxxxxxxxxxxxxxxx/
> Signed-off-by: Will Deacon <will@xxxxxxxxxx>
> ---
>  arch/powerpc/platforms/pseries/svm.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Thanks.

Acked-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>


I assume Konrad will take this via the swiotlb tree?

cheers