[PATCH v4 06/11] x86/intel_pstate: APERF/MPERF feature detect

[PATCH v4 06/11] x86/intel_pstate: APERF/MPERF feature detect

[Wei Wang]

Add support to detect the APERF/MPERF feature. Also, remove the identical
code in cpufreq.c and powernow.c.

v4 changes:
1) this is a new consolidated patch dealing with the APERF/MPERF feature
detection.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
 xen/arch/x86/acpi/cpufreq/cpufreq.c  | 6 ++----
 xen/arch/x86/acpi/cpufreq/powernow.c | 6 ++----
 xen/arch/x86/cpu/common.c            | 3 +++
 xen/include/asm-x86/cpufeature.h     | 1 +
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/acpi/cpufreq/cpufreq.c b/xen/arch/x86/acpi/cpufreq/cpufreq.c
index fa3678d..643c405 100644
--- a/xen/arch/x86/acpi/cpufreq/cpufreq.c
+++ b/xen/arch/x86/acpi/cpufreq/cpufreq.c
@@ -51,7 +51,6 @@ enum {
 };
 
 #define INTEL_MSR_RANGE         (0xffffull)
-#define CPUID_6_ECX_APERFMPERF_CAPABILITY       (0x1)
 
 struct acpi_cpufreq_data *cpufreq_drv_data[NR_CPUS];
 
@@ -352,10 +351,9 @@ static unsigned int get_cur_freq_on_cpu(unsigned int cpu)
 static void feature_detect(void *info)
 {
     struct cpufreq_policy *policy = info;
-    unsigned int eax, ecx;
+    unsigned int eax;
 
-    ecx = cpuid_ecx(6);
-    if (ecx & CPUID_6_ECX_APERFMPERF_CAPABILITY) {
+    if (boot_cpu_has(X86_FEATURE_APERFMPERF)) {
         policy->aperf_mperf = 1;
         acpi_cpufreq_driver.getavg = get_measured_perf;
     }
diff --git a/xen/arch/x86/acpi/cpufreq/powernow.c b/xen/arch/x86/acpi/cpufreq/powernow.c
index 2c9fea2..b5b752c 100644
--- a/xen/arch/x86/acpi/cpufreq/powernow.c
+++ b/xen/arch/x86/acpi/cpufreq/powernow.c
@@ -38,7 +38,6 @@
 #include <acpi/acpi.h>
 #include <acpi/cpufreq/cpufreq.h>
 
-#define CPUID_6_ECX_APERFMPERF_CAPABILITY       (0x1)
 #define CPUID_FREQ_VOLT_CAPABILITIES    0x80000007
 #define CPB_CAPABLE             0x00000200
 #define USE_HW_PSTATE           0x00000080
@@ -212,10 +211,9 @@ static int powernow_cpufreq_verify(struct cpufreq_policy *policy)
 static void feature_detect(void *info)
 {
     struct cpufreq_policy *policy = info;
-    unsigned int ecx, edx;
+    unsigned int edx;
 
-    ecx = cpuid_ecx(6);
-    if (ecx & CPUID_6_ECX_APERFMPERF_CAPABILITY) {
+    if (boot_cpu_has(X86_FEATURE_APERFMPERF)) {
         policy->aperf_mperf = 1;
         powernow_cpufreq_driver.getavg = get_measured_perf;
     }
diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index e105aeb..dba29c0 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -238,6 +238,9 @@ static void __cpuinit generic_identify(struct cpuinfo_x86 *c)
 	if ( cpu_has(c, X86_FEATURE_CLFLSH) )
 		c->x86_clflush_size = ((ebx >> 8) & 0xff) * 8;
 
+	if (cpuid_ecx(6) & 0x1)
+		set_bit(X86_FEATURE_APERFMPERF, c->x86_capability);
+
 	/* AMD-defined flags: level 0x80000001 */
 	c->extended_cpuid_level = cpuid_eax(0x80000000);
 	if ( (c->extended_cpuid_level & 0xffff0000) == 0x80000000 ) {
diff --git a/xen/include/asm-x86/cpufeature.h b/xen/include/asm-x86/cpufeature.h
index 7963a3a..efc9711 100644
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -69,6 +69,7 @@
 #define X86_FEATURE_XTOPOLOGY    (3*32+13) /* cpu topology enum extensions */
 #define X86_FEATURE_CPUID_FAULTING (3*32+14) /* cpuid faulting */
 #define X86_FEATURE_CLFLUSH_MONITOR (3*32+15) /* clflush reqd with monitor */
+#define X86_FEATURE_APERFMPERF (3*32+28) /* APERFMPERF */
 
 /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
 #define X86_FEATURE_XMM3	(4*32+ 0) /* Streaming SIMD Extensions-3 */
-- 
1.9.1

Re: [PATCH v4 06/11] x86/intel_pstate: APERF/MPERF feature detect

[Jan Beulich]

>>> On 25.06.15 at 13:16, <wei.w.wang@intel.com> wrote:
> Add support to detect the APERF/MPERF feature. Also, remove the identical
> code in cpufreq.c and powernow.c.
> 
> v4 changes:
> 1) this is a new consolidated patch dealing with the APERF/MPERF feature
> detection.
> 
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>

I would have taken this right away, if only it had been at the
beginning of the series (or stated that it's independent of the
earlier patches) and, more importantly, ...

> --- a/xen/arch/x86/cpu/common.c
> +++ b/xen/arch/x86/cpu/common.c
> @@ -238,6 +238,9 @@ static void __cpuinit generic_identify(struct cpuinfo_x86 *c)
>  	if ( cpu_has(c, X86_FEATURE_CLFLSH) )
>  		c->x86_clflush_size = ((ebx >> 8) & 0xff) * 8;
>  
> +	if (cpuid_ecx(6) & 0x1)
> +		set_bit(X86_FEATURE_APERFMPERF, c->x86_capability);

... if you hadn't used this plain 0x1 here when _both_ of the old
code pieces nicely used CPUID_6_ECX_APERFMPERF_CAPABILITY.
Bonus points for also giving a sensible name to leaf 6 and naming
its other bits code in the tree already uses (see CPUID_MWAIT_LEAF).

And of course you should check ->cpuid_level first.

Jan