powernv: Load correct TOC pointer while waking up from winkle.

[Michael Ellerman]

On Fri, 2016-05-08 at 13:43:12 UTC, Mahesh Salgaonkar wrote:
> From: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
> 
> The function pnv_restore_hyp_resource() loads the TOC into r2 from
> the invalid PACA pointer before fixing r13 value. This do not affect
> POWER ISA 3.0 but it does have an impact on POWER ISA 2.07 or less
> leading CPU to get stuck forever.
> 
> 	login: [  471.830433] Processor 120 is stuck.
> 
> 
> This can be easily reproducible using following steps:
> - Turn off SMT
> 	$ ppc64_cpu --smt=off
> - offline/online any online cpu (Thread 0 of any core which is online)
> 	$ echo 0 > /sys/devices/system/cpu/cpu<num>/online
> 	$ echo 1 > /sys/devices/system/cpu/cpu<num>/online
> 
> For POWER ISA 2.07 or less, the last bit of HSPRG0 is set indicating
> that thread is waking up from winkle. Hence, the last bit of HSPRG0(r13)
> needs to be clear before accessing it as PACA to avoid loading invalid
> values from invalid PACA pointer.
> 
> Fix this by loading TOC after r13 register is corrected.
> 
> Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/e325d76f8bd2d222a1f577aba0

cheers