Subject: Re: [v3 07/15] powerpc/perf: Add power10_feat to dt_cpu_ftrs

From: Michael Ellerman <[email-masked]>
Date: Wed, 22 Jul 2020 20:39:00 +1000

Athira Rajeev <[email-masked]> writes:
>> On 22-Jul-2020, at 10:11 AM, Jordan Niethe <[email-masked]> wrote:
>> 
>> On Sat, Jul 18, 2020 at 1:13 AM Athira Rajeev
>> <[email-masked] <mailto:[email-masked]>> wrote:
>>> 
>>> From: Madhavan Srinivasan <[email-masked]>
>>> 
>>> Add power10 feature function to dt_cpu_ftrs.c along
>>> with a power10 specific init() to initialize pmu sprs,
>>> sets the oprofile_cpu_type and cpu_features. This will
>>> enable performance monitoring unit(PMU) for Power10
>>> in CPU features with "performance-monitor-power10".
>>> 
>>> For PowerISA v3.1, BHRB disable is controlled via Monitor Mode
>>> Control Register A (MMCRA) bit, namely "BHRB Recording Disable
>>> (BHRBRD)". This patch initializes MMCRA BHRBRD to disable BHRB
>>> feature at boot for power10.
>>> 
>>> Signed-off-by: Madhavan Srinivasan <[email-masked]>
>>> ---
>>> arch/powerpc/include/asm/reg.h        |  3 +++
>>> arch/powerpc/kernel/cpu_setup_power.S |  8 ++++++++
>>> arch/powerpc/kernel/dt_cpu_ftrs.c     | 26 ++++++++++++++++++++++++++
>>> 3 files changed, 37 insertions(+)
>>> 
>>> diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
>>> index 21a1b2d..900ada1 100644
>>> --- a/arch/powerpc/include/asm/reg.h
>>> +++ b/arch/powerpc/include/asm/reg.h
>>> @@ -1068,6 +1068,9 @@
>>> #define MMCR0_PMC2_LOADMISSTIME        0x5
>>> #endif
>>> 
>>> +/* BHRB disable bit for PowerISA v3.10 */
>>> +#define MMCRA_BHRB_DISABLE     0x0000002000000000
>> Shouldn't this go under SPRN_MMCRA with the other MMCRA_*.
>
>
> Hi Jordan
>
> Ok, the definition of MMCRA is under #ifdef for 64 bit .  if I move definition of MMCRA_BHRB_DISABLE along with other SPR's, I also
> need to define this for 32-bit to satisfy core-book3s to compile as below:
>
> diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
> index 900ada10762c..7e271657b412 100644
> --- a/arch/powerpc/include/asm/reg.h
> +++ b/arch/powerpc/include/asm/reg.h
> @@ -888,6 +888,8 @@
>  #define   MMCRA_SLOT   0x07000000UL /* SLOT bits (37-39) */
>  #define   MMCRA_SLOT_SHIFT     24
>  #define   MMCRA_SAMPLE_ENABLE 0x00000001UL /* enable sampling */
> +/* BHRB disable bit for PowerISA v3.10 */
> +#define   MMCRA_BHRB_DISABLE  0x0000002000000000

I changed it to:

#define   MMCRA_BHRB_DISABLE  0x2000000000UL // BHRB disable bit for ISA v3.1

>>> diff --git a/arch/powerpc/kernel/cpu_setup_power.S b/arch/powerpc/kernel/cpu_setup_power.S
>>> index efdcfa7..b8e0d1e 100644
>>> --- a/arch/powerpc/kernel/cpu_setup_power.S
>>> +++ b/arch/powerpc/kernel/cpu_setup_power.S
>>> @@ -94,6 +94,7 @@ _GLOBAL(__restore_cpu_power8)
>>> _GLOBAL(__setup_cpu_power10)
>>>        mflr    r11
>>>        bl      __init_FSCR_power10
>>> +       bl      __init_PMU_ISA31
>> So we set MMCRA here but then aren't we still going to call __init_PMU
>> which will overwrite that?
>> Would this setting MMCRA also need to be handled in __restore_cpu_power10?
>
> Thanks for this nice catch !  When I rebased code initial phase, we didn’t had power10 part filled in.
> It was a miss from my side in adding PMu init functions and thanks for pointing this out. 
> Below patch will call __init_PMU functions in setup and restore. Please check if this looks good

Actually those changes should be in a separate patch.

This one is wiring up DT CPU features, the cpu setup routines are not
used by DT CPU features.

So please send a new patch I can insert into the series that adds the
cpu_setup_power.S changes.

cheers

> --
> diff --git a/arch/powerpc/kernel/cpu_setup_power.S b/arch/powerpc/kernel/cpu_setup_power.S
> index efdcfa714106..e672a6c5fd7c 100644
> --- a/arch/powerpc/kernel/cpu_setup_power.S
> +++ b/arch/powerpc/kernel/cpu_setup_power.S
> @@ -94,6 +94,9 @@ _GLOBAL(__restore_cpu_power8)
>  _GLOBAL(__setup_cpu_power10)
>  	mflr	r11
>  	bl	__init_FSCR_power10
> +	bl	__init_PMU
> +	bl	__init_PMU_ISA31
> +	bl	__init_PMU_HV
>  	b	1f
>  
>  _GLOBAL(__setup_cpu_power9)
> @@ -124,6 +127,9 @@ _GLOBAL(__setup_cpu_power9)
>  _GLOBAL(__restore_cpu_power10)
>  	mflr	r11
>  	bl	__init_FSCR_power10
> +	bl	__init_PMU
> +	bl	__init_PMU_ISA31
> +	bl	__init_PMU_HV
>  	b	1f
>  
>  _GLOBAL(__restore_cpu_power9)
> @@ -233,3 +239,10 @@ __init_PMU_ISA207:
>  	li	r5,0
>  	mtspr	SPRN_MMCRS,r5
>  	blr
> +
> +__init_PMU_ISA31:
> +	li	r5,0
> +	mtspr	SPRN_MMCR3,r5
> +	LOAD_REG_IMMEDIATE(r5, MMCRA_BHRB_DISABLE)
> +	mtspr	SPRN_MMCRA,r5
> +	blr
>