powernv:idle: Clear r12 on wakeup from stop lite

[Michael Ellerman]

On Wed, 2017-06-28 at 01:16:49 UTC, Akshay Adiga wrote:
> pnv_wakeup_noloss expects R12 to contain SRR1 value to determine if
> the wakeup reason is an HMI in CHECK_HMI_INTERRUPT.
> 
> When we wakeup with ESL=0, SRR1 will not contain the wakeup reason, so
> there is no point setting R12 to SRR1.
> 
> However, we don't set R12 at all and R12 contains garbage, and still
> being used to check HMI assuming that it had SRR1. causing the
> OPAL msglog to be filled with the following print:
> 	HMI: Received HMI interrupt: HMER = 0x0040000000000000
> 
> This patch clears R12 after waking up from stop with ESL=EC=0, so that
> we don't accidentally enter the HMI handler in pnv_wakeup_noloss if
> the R12[42:45] corresponds to HMI as wakeup reason.
> 
> Bug existed prior to "commit 9d29250136f6 ("powerpc/64s/idle: Avoid SRR
> usage in idle sleep/wake paths")  but was never hit in practice
> 
> Signed-off-by: Akshay Adiga <akshay.adiga at linux.vnet.ibm.com>
> Fixes: 9d29250136f6 ("powerpc/64s/idle: Avoid SRR usage in idle
> sleep/wake paths")
> Reviewed-by: Nicholas Piggin <npiggin at gmail.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/4d0d7c02df680740da41f5f92a238c

cheers