Christophe Leroy's on April 4, 2020 12:19 am:
>
>
> Le 03/04/2020 à 15:26, Nicholas Piggin a écrit :
>> This allows rtas_args to be put on the machine check stack, which
>> avoids a lot of complications with re-entrancy deadlocks.
>>
>> Reviewed-by: Mahesh Salgaonkar <mah...@linux.ibm.com>
>> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
>> ---
>> arch/powerpc/kernel/setup_64.c | 17 ++++++++++++++++-
>> 1 file changed, 16 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
>> index e05e6dd67ae6..3a2428aa3d9a 100644
>> --- a/arch/powerpc/kernel/setup_64.c
>> +++ b/arch/powerpc/kernel/setup_64.c
>> @@ -692,6 +692,9 @@ void __init exc_lvl_early_init(void)
>> void __init emergency_stack_init(void)
>> {
>> u64 limit;
>> +#ifdef CONFIG_PPC_BOOK3S_64
>
> #ifdef not needed, see below
>
>> + u64 mce_limit;
>> +#endif
>> unsigned int i;
>>
>> /*
>> @@ -710,6 +713,18 @@ void __init emergency_stack_init(void)
>> */
>> limit = min(ppc64_bolted_size(), ppc64_rma_size);
>>
>> + /*
>> + * Machine check on pseries calls rtas, but can't use the static
>> + * rtas_args due to a machine check hitting while the lock is held.
>> + * rtas args have to be under 4GB, so the machine check stack is
>> + * limited to 4GB so args can be put on stack.
>> + */
>> +#ifdef CONFIG_PPC_BOOK3S_64
>
> This ifdef is not needed. FW_FEATURE_LPAR is only possible on
> CONFIG_PPC_BOOK3S_64 (indeed only on PSERIES or PS3). On others
> firmware_has_feature(FW_FEATURE_LPAR) should return 0 at compile time.
Sure I'll remove it.
>> + mce_limit = limit;
>> + if (firmware_has_feature(FW_FEATURE_LPAR) && mce_limit >
>> 4UL*1024*1024*1024)
>> + mce_limit = 4UL*1024*1024*1024;
>
> You should use SZ_4G instead of hardcoding.
Will do.
Thanks,
Nick
