powerpc/64s: Default l1d_size to 64K in RFI fallback flush

[Michael Ellerman]

On Tue, 2018-04-17 at 01:49:20 UTC, Michael Ellerman wrote:
> From: Madhavan Srinivasan <maddy at linux.vnet.ibm.com>
> 
> If there is no d-cache-size property in the device tree, l1d_size could
> be zero. We don't actually expect that to happen, it's only been seen
> on mambo (simulator) in some configurations.
> 
> A zero-size l1d_size leads to the loop in the asm wrapping around to
> 2^64-1, and then walking off the end of the fallback area and
> eventually causing a page fault which is fatal.
> 
> Just default to 64K which is correct on some CPUs, and sane enough to
> not cause a crash on others.
> 
> Fixes: aa8a5e0062ac9 ('powerpc/64s: Add support for RFI flush of L1-D cache')
> Signed-off-by: Madhavan Srinivasan <maddy at linux.vnet.ibm.com>
> [mpe: Rewrite comment and change log]
> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>

Applied to powerpc fixes.

https://git.kernel.org/powerpc/c/9dfbf78e4114fcaf4ef61c49885c3a

cheers