tools/power/turbostat: Read energy_perf_bias from sysfs

... instead of poking at the MSR directly.
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-pm@vger.kernel.org
Link: https://lkml.kernel.org/r/20201029190259.3476-3-bp@alien8.de

tools/power/x86/turbostat/turbostat.c

@@ -1721,6 +1721,25 @@ int get_mp(int cpu, struct msr_counter *mp, unsigned long long *counterp)
 	return 0;
 }
 
+int get_epb(int cpu)
+{
+	char path[128 + PATH_BYTES];
+	int ret, epb = -1;
+	FILE *fp;
+
+	sprintf(path, "/sys/devices/system/cpu/cpu%d/power/energy_perf_bias", cpu);
+
+	fp = fopen_or_die(path, "r");
+
+	ret = fscanf(fp, "%d", &epb);
+	if (ret != 1)
+		err(1, "%s(%s)", __func__, path);
+
+	fclose(fp);
+
+	return epb;
+}
+
 void get_apic_id(struct thread_data *t)
 {
 	unsigned int eax, ebx, ecx, edx;
@@ -3631,9 +3650,8 @@ dump_sysfs_pstate_config(void)
  */
 int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 {
-	unsigned long long msr;
 	char *epb_string;
-	int cpu;
+	int cpu, epb;
 
 	if (!has_epb)
 		return 0;
@@ -3649,10 +3667,11 @@ int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 		return -1;
 	}
 
-	if (get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr))
+	epb = get_epb(cpu);
+	if (epb < 0)
 		return 0;
 
-	switch (msr & 0xF) {
+	switch (epb) {
 	case ENERGY_PERF_BIAS_PERFORMANCE:
 		epb_string = "performance";
 		break;
@@ -3666,7 +3685,7 @@ int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 		epb_string = "custom";
 		break;
 	}
-	fprintf(outf, "cpu%d: MSR_IA32_ENERGY_PERF_BIAS: 0x%08llx (%s)\n", cpu, msr, epb_string);
+	fprintf(outf, "cpu%d: EPB: %d (%s)\n", cpu, epb, epb_string);
 
 	return 0;
 }