[PATCH v3 1/6] powerpc/mm: any thread in one core can be the first to setup TLB1

[Chenhui Zhao]

On Wed, Dec 2, 2015 at 8:12 PM, Denis Kirjanov <kda at linux-powerpc.org> 
wrote:
> On 11/20/15, Chenhui Zhao <chenhui.zhao at freescale.com> wrote:
>>  On e6500, in the case of cpu hotplug, either thread in one core
>>  may be the first thread initilzing the TLB1. The subsequent threads
>>  must not setup it again.
>> 
>>  The code is derived from the comment of Scott Wood.
>> 
>>  Signed-off-by: Chenhui Zhao <chenhui.zhao at freescale.com>
>>  ---
>>   arch/powerpc/include/asm/cputhreads.h | 7 +++++++
>>   arch/powerpc/mm/tlb_nohash.c          | 4 +---
>>   2 files changed, 8 insertions(+), 3 deletions(-)
>> 
>>  diff --git a/arch/powerpc/include/asm/cputhreads.h
>>  b/arch/powerpc/include/asm/cputhreads.h
>>  index ba42e46..b56cece 100644
>>  --- a/arch/powerpc/include/asm/cputhreads.h
>>  +++ b/arch/powerpc/include/asm/cputhreads.h
>>  @@ -94,6 +94,13 @@ static inline int cpu_last_thread_sibling(int 
>> cpu)
>>   	return cpu | (threads_per_core - 1);
>>   }
>> 
>>  +static inline u32 get_tensr(void)
>>  +{
>>  +	if (cpu_has_feature(CPU_FTR_SMT))
>>  +		return mfspr(SPRN_TENSR);
>>  +	else
>>  +		return 1;
>>  +}
> If i get it right, SPRN_TENSR used in the code only if CONFIG_PPC64
> is defined. Then we can make it noop on ppc32.
> 
> Thanks!

Yeah, SPRN_TENSR is defined when CONFIG_BOOKE or CONFIG_40x is enabled. 
I'd like to change the code like:

static inline u32 get_tensr(void)
{
#ifdef CONFIG_BOOKE
        if (cpu_has_feature(CPU_FTR_SMT))
                return mfspr(SPRN_TENSR);
#endif
        return 1;
}

Thanks,
Chenhui