Re: [kvm-unit-tests PATCH v4 1/9] s390x: saving regs for interrupts

[Pierre Morel <pmorel@linux.ibm.com>]

On 2019-12-12 10:24, Janosch Frank wrote:
> On 12/11/19 4:46 PM, Pierre Morel wrote:
>> If we use multiple source of interrupts, for exemple, using SCLP
> 
> s/exemple/example/

OK, thanks

> 
>> console to print information while using I/O interrupts, we need
>> to have a re-entrant register saving interruption handling.
>>
>> Instead of saving at a static memory address, let's save the base
>> registers and the floating point registers on the stack.
>>
>> Note that we keep the static register saving to recover from the
>> RESET tests.
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>>   s390x/cstart64.S | 25 +++++++++++++++++++++++--
>>   1 file changed, 23 insertions(+), 2 deletions(-)
>>
>> diff --git a/s390x/cstart64.S b/s390x/cstart64.S
>> index 86dd4c4..ff05f9b 100644
>> --- a/s390x/cstart64.S
>> +++ b/s390x/cstart64.S
>> @@ -118,6 +118,25 @@ memsetxc:
>>   	lmg	%r0, %r15, GEN_LC_SW_INT_GRS
>>   	.endm
>>> +	.macro SAVE_IRQ_REGS
> 
> Maybe add comments to the start of the macros like:
> "Save registers on the stack, so we can have stacked interrupts."

OK.

> 
>> +	slgfi   %r15, 15 * 8
>> +	stmg    %r0, %r14, 0(%r15)
>> +	slgfi   %r15, 16 * 8
>> +	.irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
>> +	std	\i, \i * 8(%r15)
>> +	.endr
>> +	lgr     %r2, %r15
> 
> What's that doing?

Passing a parameter to the saved registers to the handler.
makes me think that since I reworked the interrupt handler to add 
registration the parameter disappeared...

I will remove this line and come back with a new series at the time we 
need to access the registers.

> 
>> +	.endm
>> +
>> +	.macro RESTORE_IRQ_REGS
>> +	.irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
>> +	ld	\i, \i * 8(%r15)
>> +	.endr
>> +	algfi   %r15, 16 * 8
>> +	lmg     %r0, %r14, 0(%r15)
>> +	algfi   %r15, 15 * 8
>> +	.endm
>> +
>>   .section .text
>>   /*
>>    * load_reset calling convention:
>> @@ -154,6 +173,8 @@ diag308_load_reset:
>>   	lpswe	GEN_LC_SW_INT_PSW
>>   1:	br	%r14
>>   
>> +
>> +
> 
> Still not fixed

sorry I did not see this

Thanks for review,
Regards,
Pierre


-- 
Pierre Morel
IBM Lab Boeblingen