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

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

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On 12/11/19 4:46 PM, Pierre Morel wrote:
> If we use multiple source of interrupts, for exemple, using SCLP

s/exemple/example/

> 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."

> +	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?

> +	.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

>  .globl smp_cpu_setup_state
>  smp_cpu_setup_state:
>  	xgr	%r1, %r1
> @@ -180,9 +201,9 @@ mcck_int:
>  	lpswe	GEN_LC_MCCK_OLD_PSW
>  
>  io_int:
> -	SAVE_REGS
> +	SAVE_IRQ_REGS
>  	brasl	%r14, handle_io_int
> -	RESTORE_REGS
> +	RESTORE_IRQ_REGS
>  	lpswe	GEN_LC_IO_OLD_PSW
>  
>  svc_int:
> 



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