cpupower: Add CPUPOWER_CAP_AMD_HW_PSTATE cpuid caps flag

Add a check in get_cpu_info() for the ability to read frequencies
from hardware and set the CPUPOWER_CAP_AMD_HW_PSTATE cpuid flag.
The cpuid flag is set when CPUID_80000007_EDX[7] is set,
which is all families >= 10h. The check excludes family 14h
because HW pstate reporting was not implemented on family 14h.

This is intended to reduce family checks in the main code paths.
Signed-off-by: Nathan Fontenot <nathan.fontenot@amd.com>
Reviewed-by: Robert Richter <rrichter@amd.com>
Reviewed-by: skhan@linuxfoundation.org
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/power/cpupower/utils/helpers/amd.c

@@ -94,11 +94,10 @@ int decode_pstates(unsigned int cpu, unsigned int cpu_family,
 	union core_pstate pstate;
 	unsigned long long val;
 
-	/* Only read out frequencies from HW when CPU might be boostable
-	   to keep the code as short and clean as possible.
-	   Otherwise frequencies are exported via ACPI tables.
-	*/
-	if (cpu_family < 0x10 || cpu_family == 0x14)
+	/* Only read out frequencies from HW if HW Pstate is supported,
+	 * otherwise frequencies are exported via ACPI tables.
+	 */
+	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_AMD_HW_PSTATE))
 		return -1;
 
 	if (read_msr(cpu, MSR_AMD_PSTATE_LIMIT, &val))

tools/power/cpupower/utils/helpers/cpuid.c

@@ -128,9 +128,15 @@ int get_cpu_info(struct cpupower_cpu_info *cpu_info)
 	/* AMD or Hygon Boost state enable/disable register */
 	if (cpu_info->vendor == X86_VENDOR_AMD ||
 	    cpu_info->vendor == X86_VENDOR_HYGON) {
-		if (ext_cpuid_level >= 0x80000007 &&
-		    (cpuid_edx(0x80000007) & (1 << 9)))
-			cpu_info->caps |= CPUPOWER_CAP_AMD_CPB;
+		if (ext_cpuid_level >= 0x80000007) {
+			if (cpuid_edx(0x80000007) & (1 << 9))
+				cpu_info->caps |= CPUPOWER_CAP_AMD_CPB;
+
+			if ((cpuid_edx(0x80000007) & (1 << 7)) &&
+			    cpu_info->family != 0x14)
+				/* HW pstate was not implemented in family 0x14 */
+				cpu_info->caps |= CPUPOWER_CAP_AMD_HW_PSTATE;
+		}
 
 		if (ext_cpuid_level >= 0x80000008 &&
 		    cpuid_ebx(0x80000008) & (1 << 4))

tools/power/cpupower/utils/helpers/helpers.h

@@ -70,6 +70,7 @@ enum cpupower_cpu_vendor {X86_VENDOR_UNKNOWN = 0, X86_VENDOR_INTEL,
 #define CPUPOWER_CAP_IS_SNB		0x00000020
 #define CPUPOWER_CAP_INTEL_IDA		0x00000040
 #define CPUPOWER_CAP_AMD_RDPRU		0x00000080
+#define CPUPOWER_CAP_AMD_HW_PSTATE	0x00000100
 
 #define CPUPOWER_AMD_CPBDIS		0x02000000