diff mbox series

[v8,03/24] drivers/perf: riscv: Read upper bits of a firmware counter

Message ID 20240420151741.962500-4-atishp@rivosinc.com
State Accepted
Headers show
Series RISC-V SBI v2.0 PMU improvements and Perf sampling in KVM guest | expand

Commit Message

Atish Kumar Patra April 20, 2024, 3:17 p.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(-)
diff mbox series

Patch

diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
index 3e44d2fb8bf8..1823ffb25d35 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: %ld\n",
+					  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);