Re: [PATCH v2 07/10] s390x: smp: Use full PSW to bringup new cpu

[Janosch Frank <frankja@linux.ibm.com>]

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On 4/24/20 12:09 PM, David Hildenbrand wrote:
> On 23.04.20 11:10, Janosch Frank wrote:
>> Up to now we ignored the psw mask and only used the psw address when
>> bringing up a new cpu. For DAT we need to also load the mask, so let's
>> do that.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
>> ---
>>  lib/s390x/smp.c  | 2 ++
>>  s390x/cstart64.S | 3 ++-
>>  2 files changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/lib/s390x/smp.c b/lib/s390x/smp.c
>> index 3f86243..6ef0335 100644
>> --- a/lib/s390x/smp.c
>> +++ b/lib/s390x/smp.c
>> @@ -202,6 +202,8 @@ int smp_cpu_setup(uint16_t addr, struct psw psw)
>>  	cpu->stack = (uint64_t *)alloc_pages(2);
>>  
>>  	/* Start without DAT and any other mask bits. */
>> +	cpu->lowcore->sw_int_psw.mask = psw.mask;
>> +	cpu->lowcore->sw_int_psw.addr = psw.addr;
>>  	cpu->lowcore->sw_int_grs[14] = psw.addr;
> 
> Do we still have to set sw_int_grs[14] ?
> 
r14 is saved to restart_new so we don't go through setup twice.
We could instead copy cpu->lowcore->sw_int_psw.addr to restart new, but
that means more changes than the removal of one line.

Also, what about backtraces or plain old debug?
Having r14 is a good backup to have IMHO.


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