[PATCH] arm: pmu: Get PMU working when the A53 is run in 32 bit mode

[PATCH] arm: pmu: Get PMU working when the A53 is run in 32 bit mode

[Al Cooper]

From: Al Cooper <al.cooper@broadcom.com>

When the A53 is run in A15 (32 bit) mode, the registers used to
access the counters are A15 style registers, but the actual
counters are the A53 counters not A15 counters. This patch will
select a PMU counters map for the A53 if the device tree pmu
"compatible" property includes "arm,cortex-a53-pmu".

Signed-off-by: Al Cooper <alcooperx@gmail.com>
---
 arch/arm/kernel/perf_event_v7.c | 105 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)

diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
index ab6522b..f714a28 100644
--- a/arch/arm/kernel/perf_event_v7.c
+++ b/arch/arm/kernel/perf_event_v7.c
@@ -147,6 +147,49 @@
 
 #define SCORPION_ITLB_MISS				0x12021
 
+/* ARMV8 A53 events when running in A15 mode. */
+#define ARMV8_PMUV3_PERFCTR_INST_RETIRED			0x08
+#define ARMV8_PMUV3_PERFCTR_PC_WRITE_RETIRED			0x0C
+
+#define ARMV8_PMUV3_PERFCTR_SW_INCR				0x00
+#define ARMV8_PMUV3_PERFCTR_L1D_CACHE_REFILL			0x03
+#define ARMV8_PMUV3_PERFCTR_L1D_CACHE				0x04
+#define ARMV8_PMUV3_PERFCTR_BR_MIS_PRED				0x10
+#define ARMV8_PMUV3_PERFCTR_CPU_CYCLES				0x11
+#define ARMV8_PMUV3_PERFCTR_BR_PRED				0x12
+
+#define ARMV8_PMUV3_PERFCTR_L1I_CACHE_REFILL			0x01
+#define ARMV8_PMUV3_PERFCTR_L1I_TLB_REFILL			0x02
+#define ARMV8_PMUV3_PERFCTR_L1D_TLB_REFILL			0x05
+#define ARMV8_PMUV3_PERFCTR_MEM_ACCESS				0x13
+#define ARMV8_PMUV3_PERFCTR_L1I_CACHE				0x14
+#define ARMV8_PMUV3_PERFCTR_L1D_CACHE_WB			0x15
+#define ARMV8_PMUV3_PERFCTR_L2D_CACHE				0x16
+#define ARMV8_PMUV3_PERFCTR_L2D_CACHE_REFILL			0x17
+#define ARMV8_PMUV3_PERFCTR_L2D_CACHE_WB			0x18
+#define ARMV8_PMUV3_PERFCTR_BUS_ACCESS				0x19
+#define ARMV8_PMUV3_PERFCTR_MEMORY_ERROR			0x1A
+#define ARMV8_PMUV3_PERFCTR_BUS_CYCLES				0x1D
+#define ARMV8_PMUV3_PERFCTR_L1D_CACHE_ALLOCATE			0x1F
+#define ARMV8_PMUV3_PERFCTR_L2D_CACHE_ALLOCATE			0x20
+#define ARMV8_PMUV3_PERFCTR_BR_MIS_PRED_RETIRED			0x22
+#define ARMV8_PMUV3_PERFCTR_STALL_FRONTEND			0x23
+#define ARMV8_PMUV3_PERFCTR_STALL_BACKEND			0x24
+#define ARMV8_PMUV3_PERFCTR_L1D_TLB				0x25
+#define ARMV8_PMUV3_PERFCTR_L1I_TLB				0x26
+#define ARMV8_PMUV3_PERFCTR_L2I_CACHE				0x27
+#define ARMV8_PMUV3_PERFCTR_L2I_CACHE_REFILL			0x28
+#define ARMV8_PMUV3_PERFCTR_L3D_CACHE_ALLOCATE			0x29
+#define ARMV8_PMUV3_PERFCTR_L3D_CACHE_REFILL			0x2A
+#define ARMV8_PMUV3_PERFCTR_L3D_CACHE				0x2B
+#define ARMV8_PMUV3_PERFCTR_L3D_CACHE_WB			0x2C
+#define ARMV8_PMUV3_PERFCTR_L2D_TLB_REFILL			0x2D
+#define ARMV8_PMUV3_PERFCTR_L2I_TLB_REFILL			0x2E
+#define ARMV8_PMUV3_PERFCTR_L2D_TLB				0x2F
+#define ARMV8_PMUV3_PERFCTR_L2I_TLB				0x30
+
+#define ARMV8_A53_PERFCTR_PREF_LINEFILL				0xC2
+
 /*
  * Cortex-A8 HW events mapping
  *
@@ -340,6 +383,48 @@
 };
 
 /*
+ * Cortex-A53 HW events mapping when running the A53 in A15 mode
+ */
+static const unsigned armv7_a53_perf_map[PERF_COUNT_HW_MAX] = {
+	PERF_MAP_ALL_UNSUPPORTED,
+	[PERF_COUNT_HW_CPU_CYCLES]		= ARMV8_PMUV3_PERFCTR_CPU_CYCLES,
+	[PERF_COUNT_HW_INSTRUCTIONS]		= ARMV8_PMUV3_PERFCTR_INST_RETIRED,
+	[PERF_COUNT_HW_CACHE_REFERENCES]	= ARMV8_PMUV3_PERFCTR_L1D_CACHE,
+	[PERF_COUNT_HW_CACHE_MISSES]		= ARMV8_PMUV3_PERFCTR_L1D_CACHE_REFILL,
+	[PERF_COUNT_HW_BRANCH_INSTRUCTIONS]	= ARMV8_PMUV3_PERFCTR_PC_WRITE_RETIRED,
+	[PERF_COUNT_HW_BRANCH_MISSES]		= ARMV8_PMUV3_PERFCTR_BR_MIS_PRED,
+	[PERF_COUNT_HW_BUS_CYCLES]		= ARMV8_PMUV3_PERFCTR_BUS_CYCLES,
+};
+
+static const unsigned armv7_a53_perf_cache_map[PERF_COUNT_HW_CACHE_MAX]
+					[PERF_COUNT_HW_CACHE_OP_MAX]
+					[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
+	PERF_CACHE_MAP_ALL_UNSUPPORTED,
+
+	[C(L1D)][C(OP_READ)][C(RESULT_ACCESS)]	= ARMV8_PMUV3_PERFCTR_L1D_CACHE,
+	[C(L1D)][C(OP_READ)][C(RESULT_MISS)]	= ARMV8_PMUV3_PERFCTR_L1D_CACHE_REFILL,
+	[C(L1D)][C(OP_WRITE)][C(RESULT_ACCESS)]	= ARMV8_PMUV3_PERFCTR_L1D_CACHE,
+	[C(L1D)][C(OP_WRITE)][C(RESULT_MISS)]	= ARMV8_PMUV3_PERFCTR_L1D_CACHE_REFILL,
+	[C(L1D)][C(OP_PREFETCH)][C(RESULT_MISS)] = ARMV8_A53_PERFCTR_PREF_LINEFILL,
+
+	[C(L1I)][C(OP_READ)][C(RESULT_ACCESS)]	= ARMV8_PMUV3_PERFCTR_L1I_CACHE,
+	[C(L1I)][C(OP_READ)][C(RESULT_MISS)]	= ARMV8_PMUV3_PERFCTR_L1I_CACHE_REFILL,
+
+	[C(LL)][C(OP_READ)][C(RESULT_ACCESS)]   = ARMV8_PMUV3_PERFCTR_L2D_CACHE,
+	[C(LL)][C(OP_READ)][C(RESULT_MISS)]     = ARMV8_PMUV3_PERFCTR_L2D_CACHE_REFILL,
+	[C(LL)][C(OP_WRITE)][C(RESULT_ACCESS)]  = ARMV8_PMUV3_PERFCTR_L2D_CACHE,
+	[C(LL)][C(OP_WRITE)][C(RESULT_MISS)]    = ARMV8_PMUV3_PERFCTR_L2D_CACHE_REFILL,
+
+	[C(DTLB)][C(OP_READ)][C(RESULT_MISS)]   = ARMV8_PMUV3_PERFCTR_L1D_TLB_REFILL,
+	[C(ITLB)][C(OP_READ)][C(RESULT_MISS)]	= ARMV8_PMUV3_PERFCTR_L1I_TLB_REFILL,
+
+	[C(BPU)][C(OP_READ)][C(RESULT_ACCESS)]	= ARMV8_PMUV3_PERFCTR_BR_PRED,
+	[C(BPU)][C(OP_READ)][C(RESULT_MISS)]	= ARMV8_PMUV3_PERFCTR_BR_MIS_PRED,
+	[C(BPU)][C(OP_WRITE)][C(RESULT_ACCESS)]	= ARMV8_PMUV3_PERFCTR_BR_PRED,
+	[C(BPU)][C(OP_WRITE)][C(RESULT_MISS)]	= ARMV8_PMUV3_PERFCTR_BR_MIS_PRED,
+};
+
+/*
  * Cortex-A7 HW events mapping
  */
 static const unsigned armv7_a7_perf_map[PERF_COUNT_HW_MAX] = {
@@ -1129,6 +1214,12 @@ static int armv7_a15_map_event(struct perf_event *event)
 				&armv7_a15_perf_cache_map, 0xFF);
 }
 
+static int armv7_a53_map_event(struct perf_event *event)
+{
+	return armpmu_map_event(event, &armv7_a53_perf_map,
+				&armv7_a53_perf_cache_map, 0xFF);
+}
+
 static int armv7_a7_map_event(struct perf_event *event)
 {
 	return armpmu_map_event(event, &armv7_a7_perf_map,
@@ -1240,6 +1331,19 @@ static int armv7_a15_pmu_init(struct arm_pmu *cpu_pmu)
 	return armv7_probe_num_events(cpu_pmu);
 }
 
+static int armv7_a53_pmu_init(struct arm_pmu *cpu_pmu)
+{
+	armv7pmu_init(cpu_pmu);
+	cpu_pmu->name		= "armv7_cortex_a15_on_a53";
+	cpu_pmu->map_event	= armv7_a53_map_event;
+	cpu_pmu->set_event_filter = armv7pmu_set_event_filter;
+	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_EVENTS] =
+		&armv7_pmuv2_events_attr_group;
+	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_FORMATS] =
+		&armv7_pmu_format_attr_group;
+	return armv7_probe_num_events(cpu_pmu);
+}
+
 static int armv7_a7_pmu_init(struct arm_pmu *cpu_pmu)
 {
 	armv7pmu_init(cpu_pmu);
@@ -2000,6 +2104,7 @@ static int scorpion_mp_pmu_init(struct arm_pmu *cpu_pmu)
 }
 
 static const struct of_device_id armv7_pmu_of_device_ids[] = {
+	{.compatible = "arm,cortex-a53-pmu",	.data = armv7_a53_pmu_init},
 	{.compatible = "arm,cortex-a17-pmu",	.data = armv7_a17_pmu_init},
 	{.compatible = "arm,cortex-a15-pmu",	.data = armv7_a15_pmu_init},
 	{.compatible = "arm,cortex-a12-pmu",	.data = armv7_a12_pmu_init},
-- 
1.9.0.138.g2de3478

[PATCH] arm: pmu: Get PMU working when the A53 is run in 32 bit mode

[Marc Zyngier]

Hi Al,

On 02/05/17 15:01, Al Cooper wrote:
> From: Al Cooper <al.cooper@broadcom.com>
> 
> When the A53 is run in A15 (32 bit) mode, the registers used to
> access the counters are A15 style registers, but the actual
> counters are the A53 counters not A15 counters. This patch will
> select a PMU counters map for the A53 if the device tree pmu
> "compatible" property includes "arm,cortex-a53-pmu".

I wasn't aware of an "A15 mode"! Is there an ARM3 mode, while we're at
it? ;-)

More seriously, you seem to take the problem from the wrong end. If you
have an ARMv8 core, you should use the PMUv3 driver (because that is
what your A53 has), and not the ARMv7 PMU.

To that affect, I've posted this[1] a while ago. Can you please give it
a go?

Thanks,

	M.

[1]: https://www.spinics.net/lists/arm-kernel/msg571476.html
-- 
Jazz is not dead. It just smells funny...

[PATCH] arm: pmu: Get PMU working when the A53 is run in 32 bit mode

[Florian Fainelli]

Hi Mark,

On 05/02/2017 07:17 AM, Marc Zyngier wrote:
> Hi Al,
> 
> On 02/05/17 15:01, Al Cooper wrote:
>> From: Al Cooper <al.cooper@broadcom.com>
>>
>> When the A53 is run in A15 (32 bit) mode, the registers used to
>> access the counters are A15 style registers, but the actual
>> counters are the A53 counters not A15 counters. This patch will
>> select a PMU counters map for the A53 if the device tree pmu
>> "compatible" property includes "arm,cortex-a53-pmu".
> 
> I wasn't aware of an "A15 mode"! Is there an ARM3 mode, while we're at
> it? ;-)

This is referring to how our Device Tree and kernel end-up "viewing" the
PMU (based on provided compatible strings) but this probably should be
omitted for clarity.

> 
> More seriously, you seem to take the problem from the wrong end. If you
> have an ARMv8 core, you should use the PMUv3 driver (because that is
> what your A53 has), and not the ARMv7 PMU.
> 
> To that affect, I've posted this[1] a while ago. Can you please give it
> a go?

That seems to be the right direction, however don't you also need to
possibly expose other PMU types as well? Cortex-A53 and Cortex-A57 PMUs
(and possibly more) for instance because there are additional counters
that can be defined specifically for those, e.g: LL = L2 cache on A53,
see [1].

[1]:
https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/commit/?h=for-next/core&id=f5337346cd8fe1b105f319b4b7fb06fe25c54480

Thanks!

> 
> Thanks,
> 
> 	M.
> 
> [1]: https://www.spinics.net/lists/arm-kernel/msg571476.html
> 


-- 
Florian

[PATCH] arm: pmu: Get PMU working when the A53 is run in 32 bit mode

[Marc Zyngier]

On Tue, May 02 2017 at  4:51:55 pm BST, Florian Fainelli <f.fainelli@gmail.com> wrote:
> Hi Mark,
>
> On 05/02/2017 07:17 AM, Marc Zyngier wrote:
>> Hi Al,
>> 
>> On 02/05/17 15:01, Al Cooper wrote:
>>> From: Al Cooper <al.cooper@broadcom.com>
>>>
>>> When the A53 is run in A15 (32 bit) mode, the registers used to
>>> access the counters are A15 style registers, but the actual
>>> counters are the A53 counters not A15 counters. This patch will
>>> select a PMU counters map for the A53 if the device tree pmu
>>> "compatible" property includes "arm,cortex-a53-pmu".
>> 
>> I wasn't aware of an "A15 mode"! Is there an ARM3 mode, while we're at
>> it? ;-)
>
> This is referring to how our Device Tree and kernel end-up "viewing" the
> PMU (based on provided compatible strings) but this probably should be
> omitted for clarity.

That's certainly wrong from both an architectural and implementation
PoV. Although there is some level of compatibility between the ARMv7 and
ARMv8 PMU architectures, they are distinct beasts.

>> 
>> More seriously, you seem to take the problem from the wrong end. If you
>> have an ARMv8 core, you should use the PMUv3 driver (because that is
>> what your A53 has), and not the ARMv7 PMU.
>> 
>> To that affect, I've posted this[1] a while ago. Can you please give it
>> a go?
>
> That seems to be the right direction, however don't you also need to
> possibly expose other PMU types as well? Cortex-A53 and Cortex-A57 PMUs
> (and possibly more) for instance because there are additional counters
> that can be defined specifically for those, e.g: LL = L2 cache on A53,
> see [1].

That's pretty much orthogonal. Once we have a common driver for PMUv3 on
both 32 and 64bit, adding implementation-specific events can be done for
both architecture.

Thanks,

	M.
-- 
Jazz is not dead, it just smell funny.

[PATCH] arm: pmu: Get PMU working when the A53 is run in 32 bit mode

[Florian Fainelli]

On 05/02/2017 09:50 AM, Marc Zyngier wrote:
> On Tue, May 02 2017 at  4:51:55 pm BST, Florian Fainelli <f.fainelli@gmail.com> wrote:
>> Hi Mark,
>>
>> On 05/02/2017 07:17 AM, Marc Zyngier wrote:
>>> Hi Al,
>>>
>>> On 02/05/17 15:01, Al Cooper wrote:
>>>> From: Al Cooper <al.cooper@broadcom.com>
>>>>
>>>> When the A53 is run in A15 (32 bit) mode, the registers used to
>>>> access the counters are A15 style registers, but the actual
>>>> counters are the A53 counters not A15 counters. This patch will
>>>> select a PMU counters map for the A53 if the device tree pmu
>>>> "compatible" property includes "arm,cortex-a53-pmu".
>>>
>>> I wasn't aware of an "A15 mode"! Is there an ARM3 mode, while we're at
>>> it? ;-)
>>
>> This is referring to how our Device Tree and kernel end-up "viewing" the
>> PMU (based on provided compatible strings) but this probably should be
>> omitted for clarity.
> 
> That's certainly wrong from both an architectural and implementation
> PoV. Although there is some level of compatibility between the ARMv7 and
> ARMv8 PMU architectures, they are distinct beasts.

Yes, we are well aware of that, which is why I don't think it's even
relevant to this discussion here because it's a known implementation
issue on our end.

> 
>>>
>>> More seriously, you seem to take the problem from the wrong end. If you
>>> have an ARMv8 core, you should use the PMUv3 driver (because that is
>>> what your A53 has), and not the ARMv7 PMU.
>>>
>>> To that affect, I've posted this[1] a while ago. Can you please give it
>>> a go?
>>
>> That seems to be the right direction, however don't you also need to
>> possibly expose other PMU types as well? Cortex-A53 and Cortex-A57 PMUs
>> (and possibly more) for instance because there are additional counters
>> that can be defined specifically for those, e.g: LL = L2 cache on A53,
>> see [1].
> 
> That's pretty much orthogonal. Once we have a common driver for PMUv3 on
> both 32 and 64bit, adding implementation-specific events can be done for
> both architecture.

My comment was not so much about the PMU-specific events, but about the
fact that if you make changes to the PMUv3 between 32-bit and 64-bit
kernels, we might as well bring all other PMU models that have a
potential for being shared between 32-bit and 64-bit in one go.
-- 
Florian

[PATCH] arm: pmu: Get PMU working when the A53 is run in 32 bit mode

[Marc Zyngier]

On Tue, May 02 2017 at  6:37:40 pm BST, Florian Fainelli <f.fainelli@gmail.com> wrote:
> On 05/02/2017 09:50 AM, Marc Zyngier wrote:
>> On Tue, May 02 2017 at  4:51:55 pm BST, Florian Fainelli <f.fainelli@gmail.com> wrote:
>>> Hi Mark,
>>>
>>> On 05/02/2017 07:17 AM, Marc Zyngier wrote:
>>>> Hi Al,
>>>>
>>>> On 02/05/17 15:01, Al Cooper wrote:
>>>>> From: Al Cooper <al.cooper@broadcom.com>
>>>>>
>>>>> When the A53 is run in A15 (32 bit) mode, the registers used to
>>>>> access the counters are A15 style registers, but the actual
>>>>> counters are the A53 counters not A15 counters. This patch will
>>>>> select a PMU counters map for the A53 if the device tree pmu
>>>>> "compatible" property includes "arm,cortex-a53-pmu".
>>>>
>>>> I wasn't aware of an "A15 mode"! Is there an ARM3 mode, while we're at
>>>> it? ;-)
>>>
>>> This is referring to how our Device Tree and kernel end-up "viewing" the
>>> PMU (based on provided compatible strings) but this probably should be
>>> omitted for clarity.
>> 
>> That's certainly wrong from both an architectural and implementation
>> PoV. Although there is some level of compatibility between the ARMv7 and
>> ARMv8 PMU architectures, they are distinct beasts.
>
> Yes, we are well aware of that, which is why I don't think it's even
> relevant to this discussion here because it's a known implementation
> issue on our end.
>
>> 
>>>>
>>>> More seriously, you seem to take the problem from the wrong end. If you
>>>> have an ARMv8 core, you should use the PMUv3 driver (because that is
>>>> what your A53 has), and not the ARMv7 PMU.
>>>>
>>>> To that affect, I've posted this[1] a while ago. Can you please give it
>>>> a go?
>>>
>>> That seems to be the right direction, however don't you also need to
>>> possibly expose other PMU types as well? Cortex-A53 and Cortex-A57 PMUs
>>> (and possibly more) for instance because there are additional counters
>>> that can be defined specifically for those, e.g: LL = L2 cache on A53,
>>> see [1].
>> 
>> That's pretty much orthogonal. Once we have a common driver for PMUv3 on
>> both 32 and 64bit, adding implementation-specific events can be done for
>> both architecture.
>
> My comment was not so much about the PMU-specific events, but about the
> fact that if you make changes to the PMUv3 between 32-bit and 64-bit
> kernels, we might as well bring all other PMU models that have a
> potential for being shared between 32-bit and 64-bit in one go.

I'm only concerned about the CPU PMU so far, as my main goal is
virtualization (and I have no desire to expose any other form of PMU to
a guest). Non-CPU PMUs should be mostly architecture agnostic already,
and thus pretty easy to enable.

Thanks,

	M.
-- 
Jazz is not dead, it just smell funny.

[PATCH] arm: pmu: Get PMU working when the A53 is run in 32 bit mode

[Florian Fainelli]

On 05/02/2017 10:53 AM, Marc Zyngier wrote:
> On Tue, May 02 2017 at  6:37:40 pm BST, Florian Fainelli <f.fainelli@gmail.com> wrote:
>> On 05/02/2017 09:50 AM, Marc Zyngier wrote:
>>> On Tue, May 02 2017 at  4:51:55 pm BST, Florian Fainelli <f.fainelli@gmail.com> wrote:
>>>> Hi Mark,
>>>>
>>>> On 05/02/2017 07:17 AM, Marc Zyngier wrote:
>>>>> Hi Al,
>>>>>
>>>>> On 02/05/17 15:01, Al Cooper wrote:
>>>>>> From: Al Cooper <al.cooper@broadcom.com>
>>>>>>
>>>>>> When the A53 is run in A15 (32 bit) mode, the registers used to
>>>>>> access the counters are A15 style registers, but the actual
>>>>>> counters are the A53 counters not A15 counters. This patch will
>>>>>> select a PMU counters map for the A53 if the device tree pmu
>>>>>> "compatible" property includes "arm,cortex-a53-pmu".
>>>>>
>>>>> I wasn't aware of an "A15 mode"! Is there an ARM3 mode, while we're at
>>>>> it? ;-)
>>>>
>>>> This is referring to how our Device Tree and kernel end-up "viewing" the
>>>> PMU (based on provided compatible strings) but this probably should be
>>>> omitted for clarity.
>>>
>>> That's certainly wrong from both an architectural and implementation
>>> PoV. Although there is some level of compatibility between the ARMv7 and
>>> ARMv8 PMU architectures, they are distinct beasts.
>>
>> Yes, we are well aware of that, which is why I don't think it's even
>> relevant to this discussion here because it's a known implementation
>> issue on our end.
>>
>>>
>>>>>
>>>>> More seriously, you seem to take the problem from the wrong end. If you
>>>>> have an ARMv8 core, you should use the PMUv3 driver (because that is
>>>>> what your A53 has), and not the ARMv7 PMU.
>>>>>
>>>>> To that affect, I've posted this[1] a while ago. Can you please give it
>>>>> a go?
>>>>
>>>> That seems to be the right direction, however don't you also need to
>>>> possibly expose other PMU types as well? Cortex-A53 and Cortex-A57 PMUs
>>>> (and possibly more) for instance because there are additional counters
>>>> that can be defined specifically for those, e.g: LL = L2 cache on A53,
>>>> see [1].
>>>
>>> That's pretty much orthogonal. Once we have a common driver for PMUv3 on
>>> both 32 and 64bit, adding implementation-specific events can be done for
>>> both architecture.
>>
>> My comment was not so much about the PMU-specific events, but about the
>> fact that if you make changes to the PMUv3 between 32-bit and 64-bit
>> kernels, we might as well bring all other PMU models that have a
>> potential for being shared between 32-bit and 64-bit in one go.
> 
> I'm only concerned about the CPU PMU so far, as my main goal is
> virtualization (and I have no desire to expose any other form of PMU to
> a guest). Non-CPU PMUs should be mostly architecture agnostic already,
> and thus pretty easy to enable.

By other PMU models here, I was actually referring to all other known
types of CPU PMU models, such as A53, A57 and so on.
-- 
Florian