Re: [PATCH v8 13/22] RISC-V: perf: Add a mechanism to defined legacy event encoding

[Atish Patra <atish.patra@linux.dev>]

On 7/7/26 12:51 AM, Yicong Yang wrote:
> On 7/1/26 4:47 PM, Atish Patra wrote:
>> From: Atish Patra <atishp@rivosinc.com>
>>
>> RISC-V ISA doesn't define any standard event encodings or specify
>> any event to counter mapping. Thus, event encoding information
>> and corresponding counter mapping fot those events needs to be
>> provided in the driver for each vendor.
>>
>> Add a framework to support that. The individual platform events
>> will be added later.
>>
>> Signed-off-by: Atish Patra <atishp@rivosinc.com>
>> ---
>>   drivers/perf/riscv_pmu_sbi.c | 70 +++++++++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 69 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
>> index c20f1e33c65d..2568c6808f5d 100644
>> --- a/drivers/perf/riscv_pmu_sbi.c
>> +++ b/drivers/perf/riscv_pmu_sbi.c
>> @@ -10,6 +10,7 @@
>>   
>>   #define pr_fmt(fmt) "riscv-pmu-sbi: " fmt
>>   
>> +#include <linux/limits.h>
>>   #include <linux/mod_devicetable.h>
>>   #include <linux/perf/riscv_pmu.h>
>>   #include <linux/platform_device.h>
>> @@ -379,6 +380,71 @@ static int pmu_sbi_check_event_info(void)
>>   	return result;
>>   }
>>   
>> +/*
>> + * Vendor specific PMU events.
>> + */
>> +struct riscv_pmu_event {
>> +	u64 event_id;
>> +	u32 counter_mask;
> could we name it as counterid_mask to match to the PMU format
> name (introduced in patch 16/22)?

Sure. I will change it.

> thanks.
>
>> +};
>> +
>> +#define HW_OP_UNSUPPORTED		U64_MAX
>> +#define CACHE_OP_UNSUPPORTED		U64_MAX
>> +
>> +#define PERF_MAP_ALL_UNSUPPORTED					\
>> +	[0 ... PERF_COUNT_HW_MAX - 1] = {HW_OP_UNSUPPORTED, 0x0}
>> +
>> +#define PERF_CACHE_MAP_ALL_UNSUPPORTED					\
>> +[0 ... PERF_COUNT_HW_CACHE_MAX - 1] = {					\
>> +	[0 ... PERF_COUNT_HW_CACHE_OP_MAX - 1] = {			\
>> +		[0 ... PERF_COUNT_HW_CACHE_RESULT_MAX - 1] = {		\
>> +			CACHE_OP_UNSUPPORTED, 0x0			\
>> +		},							\
>> +	},								\
>> +}
>> +
>> +struct riscv_vendor_pmu_events {
>> +	unsigned long vendorid;
>> +	unsigned long archid;
>> +	unsigned long implid;
>> +	const struct riscv_pmu_event *hw_event_map;
>> +	const struct riscv_pmu_event (*cache_event_map)[PERF_COUNT_HW_CACHE_OP_MAX]
>> +						       [PERF_COUNT_HW_CACHE_RESULT_MAX];
>> +};
>> +
>> +#define RISCV_VENDOR_PMU_EVENTS(_vendorid, _archid, _implid, _hw_event_map, _cache_event_map) \
>> +	{ .vendorid = _vendorid, .archid = _archid, .implid = _implid, \
>> +	  .hw_event_map = _hw_event_map, .cache_event_map = _cache_event_map },
>> +
>> +static struct riscv_vendor_pmu_events pmu_vendor_events_table[] = {
>> +};
>> +
>> +static const struct riscv_pmu_event *current_pmu_hw_event_map;
>> +static const struct riscv_pmu_event (*current_pmu_cache_event_map)[PERF_COUNT_HW_CACHE_OP_MAX]
>> +							   [PERF_COUNT_HW_CACHE_RESULT_MAX];
>> +
>> +static void __init rvpmu_vendor_register_events(void)
>> +{
>> +	int cpu = raw_smp_processor_id();
>> +	unsigned long vendor_id = riscv_cached_mvendorid(cpu);
>> +	unsigned long impl_id = riscv_cached_mimpid(cpu);
>> +	unsigned long arch_id = riscv_cached_marchid(cpu);
>> +
>> +	for (int i = 0; i < ARRAY_SIZE(pmu_vendor_events_table); i++) {
>> +		if (pmu_vendor_events_table[i].vendorid == vendor_id &&
>> +		    pmu_vendor_events_table[i].implid == impl_id &&
>> +		    pmu_vendor_events_table[i].archid == arch_id) {
>> +			current_pmu_hw_event_map = pmu_vendor_events_table[i].hw_event_map;
>> +			current_pmu_cache_event_map = pmu_vendor_events_table[i].cache_event_map;
>> +			break;
>> +		}
>> +	}
>> +
>> +	if (!current_pmu_hw_event_map || !current_pmu_cache_event_map) {
>> +		pr_info("No default PMU events found\n");
>> +	}
>> +}
>> +
>>   static void rvpmu_sbi_check_event(struct sbi_pmu_event_data *edata)
>>   {
>>   	struct sbiret ret;
>> @@ -1670,8 +1736,10 @@ static int __init rvpmu_devinit(void)
>>   	 */
>>   	if (riscv_isa_extension_available(NULL, SSCCFG) &&
>>   	    riscv_isa_extension_available(NULL, SMCDELEG) &&
>> -	    riscv_isa_extension_available(NULL, SSCSRIND))
>> +	    riscv_isa_extension_available(NULL, SSCSRIND)) {
>>   		static_branch_enable(&riscv_pmu_cdeleg_available);
>> +		rvpmu_vendor_register_events();
>> +	}
>>   
>>   	if (!(riscv_pmu_sbi_available_boot() || riscv_pmu_cdeleg_available_boot()))
>>   		return 0;