diff mbox series

[v5,03/22] drivers/perf: riscv: Read upper bits of a firmware counter

Message ID 20240403080452.1007601-4-atishp@rivosinc.com
State Changes Requested
Headers show
Series RISC-V SBI v2.0 PMU improvements and Perf sampling in KVM guest | expand

Commit Message

Atish Kumar Patra April 3, 2024, 8:04 a.m. UTC 
SBI v2.0 introduced a explicit function to read the upper 32 bits
for any firmware counter width that is longer than 32bits.
This is only applicable for RV32 where firmware counter can be
64 bit.

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
---
 drivers/perf/riscv_pmu_sbi.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

Comments

Andrew Jones April 4, 2024, 11:02 a.m. UTC | #1 
On Wed, Apr 03, 2024 at 01:04:32AM -0700, Atish Patra wrote:
> SBI v2.0 introduced a explicit function to read the upper 32 bits
> for any firmware counter width that is longer than 32bits.
> This is only applicable for RV32 where firmware counter can be
> 64 bit.
> 
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
> Reviewed-by: Anup Patel <anup@brainfault.org>
> Signed-off-by: Atish Patra <atishp@rivosinc.com>
> ---
>  drivers/perf/riscv_pmu_sbi.c | 25 ++++++++++++++++++++-----
>  1 file changed, 20 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> index 3e44d2fb8bf8..babf1b9a4dbe 100644
> --- a/drivers/perf/riscv_pmu_sbi.c
> +++ b/drivers/perf/riscv_pmu_sbi.c
> @@ -57,6 +57,8 @@ asm volatile(ALTERNATIVE(						\
>  PMU_FORMAT_ATTR(event, "config:0-47");
>  PMU_FORMAT_ATTR(firmware, "config:63");
>  
> +static bool sbi_v2_available;
> +
>  static struct attribute *riscv_arch_formats_attr[] = {
>  	&format_attr_event.attr,
>  	&format_attr_firmware.attr,
> @@ -511,19 +513,29 @@ static u64 pmu_sbi_ctr_read(struct perf_event *event)
>  	struct hw_perf_event *hwc = &event->hw;
>  	int idx = hwc->idx;
>  	struct sbiret ret;
> -	union sbi_pmu_ctr_info info;
>  	u64 val = 0;
> +	union sbi_pmu_ctr_info info = pmu_ctr_list[idx];
>  
>  	if (pmu_sbi_is_fw_event(event)) {
>  		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
>  				hwc->idx, 0, 0, 0, 0, 0);
> -		if (!ret.error)
> -			val = ret.value;
> +		if (ret.error)
> +			return 0;
> +
> +		val = ret.value;
> +		if (IS_ENABLED(CONFIG_32BIT) && sbi_v2_available && info.width >= 32) {
> +			ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ_HI,
> +					hwc->idx, 0, 0, 0, 0, 0);
> +			if (!ret.error)
> +				val |= ((u64)ret.value << 32);
> +			else
> +				WARN_ONCE(1, "Unable to read upper 32 bits of firmware counter error: %d\n",
> +					  sbi_err_map_linux_errno(ret.error));

I don't think we should use sbi_err_map_linux_errno() in this case since
we don't have a 1:1 mapping of SBI errors to Linux errors and we don't
propagate the error as a Linux error. For warnings, it's better to output
the exact SBI error.

> +		}
>  	} else {
> -		info = pmu_ctr_list[idx];
>  		val = riscv_pmu_ctr_read_csr(info.csr);
>  		if (IS_ENABLED(CONFIG_32BIT))
> -			val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 31 | val;
> +			val |= ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32;
>  	}
>  
>  	return val;
> @@ -1135,6 +1147,9 @@ static int __init pmu_sbi_devinit(void)
>  		return 0;
>  	}
>  
> +	if (sbi_spec_version >= sbi_mk_version(2, 0))
> +		sbi_v2_available = true;
> +
>  	ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_RISCV_STARTING,
>  				      "perf/riscv/pmu:starting",
>  				      pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);
> -- 
> 2.34.1
>

Thanks,
drew
Atish Kumar Patra April 9, 2024, 12:04 a.m. UTC | #2 
On 4/4/24 04:02, Andrew Jones wrote:
> On Wed, Apr 03, 2024 at 01:04:32AM -0700, Atish Patra wrote:
>> SBI v2.0 introduced a explicit function to read the upper 32 bits
>> for any firmware counter width that is longer than 32bits.
>> This is only applicable for RV32 where firmware counter can be
>> 64 bit.
>>
>> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
>> Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
>> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
>> Reviewed-by: Anup Patel <anup@brainfault.org>
>> Signed-off-by: Atish Patra <atishp@rivosinc.com>
>> ---
>>   drivers/perf/riscv_pmu_sbi.c | 25 ++++++++++++++++++++-----
>>   1 file changed, 20 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
>> index 3e44d2fb8bf8..babf1b9a4dbe 100644
>> --- a/drivers/perf/riscv_pmu_sbi.c
>> +++ b/drivers/perf/riscv_pmu_sbi.c
>> @@ -57,6 +57,8 @@ asm volatile(ALTERNATIVE(						\
>>   PMU_FORMAT_ATTR(event, "config:0-47");
>>   PMU_FORMAT_ATTR(firmware, "config:63");
>>   
>> +static bool sbi_v2_available;
>> +
>>   static struct attribute *riscv_arch_formats_attr[] = {
>>   	&format_attr_event.attr,
>>   	&format_attr_firmware.attr,
>> @@ -511,19 +513,29 @@ static u64 pmu_sbi_ctr_read(struct perf_event *event)
>>   	struct hw_perf_event *hwc = &event->hw;
>>   	int idx = hwc->idx;
>>   	struct sbiret ret;
>> -	union sbi_pmu_ctr_info info;
>>   	u64 val = 0;
>> +	union sbi_pmu_ctr_info info = pmu_ctr_list[idx];
>>   
>>   	if (pmu_sbi_is_fw_event(event)) {
>>   		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
>>   				hwc->idx, 0, 0, 0, 0, 0);
>> -		if (!ret.error)
>> -			val = ret.value;
>> +		if (ret.error)
>> +			return 0;
>> +
>> +		val = ret.value;
>> +		if (IS_ENABLED(CONFIG_32BIT) && sbi_v2_available && info.width >= 32) {
>> +			ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ_HI,
>> +					hwc->idx, 0, 0, 0, 0, 0);
>> +			if (!ret.error)
>> +				val |= ((u64)ret.value << 32);
>> +			else
>> +				WARN_ONCE(1, "Unable to read upper 32 bits of firmware counter error: %d\n",
>> +					  sbi_err_map_linux_errno(ret.error));
> 
> I don't think we should use sbi_err_map_linux_errno() in this case since
> we don't have a 1:1 mapping of SBI errors to Linux errors and we don't
> propagate the error as a Linux error. For warnings, it's better to output
> the exact SBI error.
> 

Sure. Fixed it.

>> +		}
>>   	} else {
>> -		info = pmu_ctr_list[idx];
>>   		val = riscv_pmu_ctr_read_csr(info.csr);
>>   		if (IS_ENABLED(CONFIG_32BIT))
>> -			val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 31 | val;
>> +			val |= ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32;
>>   	}
>>   
>>   	return val;
>> @@ -1135,6 +1147,9 @@ static int __init pmu_sbi_devinit(void)
>>   		return 0;
>>   	}
>>   
>> +	if (sbi_spec_version >= sbi_mk_version(2, 0))
>> +		sbi_v2_available = true;
>> +
>>   	ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_RISCV_STARTING,
>>   				      "perf/riscv/pmu:starting",
>>   				      pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);
>> -- 
>> 2.34.1
>>
> 
> Thanks,
> drew
diff mbox series

Patch

diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
index 3e44d2fb8bf8..babf1b9a4dbe 100644
--- a/drivers/perf/riscv_pmu_sbi.c
+++ b/drivers/perf/riscv_pmu_sbi.c
@@ -57,6 +57,8 @@  asm volatile(ALTERNATIVE(						\
 PMU_FORMAT_ATTR(event, "config:0-47");
 PMU_FORMAT_ATTR(firmware, "config:63");
 
+static bool sbi_v2_available;
+
 static struct attribute *riscv_arch_formats_attr[] = {
 	&format_attr_event.attr,
 	&format_attr_firmware.attr,
@@ -511,19 +513,29 @@  static u64 pmu_sbi_ctr_read(struct perf_event *event)
 	struct hw_perf_event *hwc = &event->hw;
 	int idx = hwc->idx;
 	struct sbiret ret;
-	union sbi_pmu_ctr_info info;
 	u64 val = 0;
+	union sbi_pmu_ctr_info info = pmu_ctr_list[idx];
 
 	if (pmu_sbi_is_fw_event(event)) {
 		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
 				hwc->idx, 0, 0, 0, 0, 0);
-		if (!ret.error)
-			val = ret.value;
+		if (ret.error)
+			return 0;
+
+		val = ret.value;
+		if (IS_ENABLED(CONFIG_32BIT) && sbi_v2_available && info.width >= 32) {
+			ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ_HI,
+					hwc->idx, 0, 0, 0, 0, 0);
+			if (!ret.error)
+				val |= ((u64)ret.value << 32);
+			else
+				WARN_ONCE(1, "Unable to read upper 32 bits of firmware counter error: %d\n",
+					  sbi_err_map_linux_errno(ret.error));
+		}
 	} else {
-		info = pmu_ctr_list[idx];
 		val = riscv_pmu_ctr_read_csr(info.csr);
 		if (IS_ENABLED(CONFIG_32BIT))
-			val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 31 | val;
+			val |= ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32;
 	}
 
 	return val;
@@ -1135,6 +1147,9 @@  static int __init pmu_sbi_devinit(void)
 		return 0;
 	}
 
+	if (sbi_spec_version >= sbi_mk_version(2, 0))
+		sbi_v2_available = true;
+
 	ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_RISCV_STARTING,
 				      "perf/riscv/pmu:starting",
 				      pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);