Xen devel - May 2010 - [PATCH, v2] x86/cpufreq: fix turbo mode detection

{acpi,powernow}_cpufreq_cpu_init() generally don''t run on the CPU the
policy they deal with is related to, hence using cpuid() directly
works only as long as all CPUs in the system are identical (which
admittedly is commonly the case).

Further add a per-policy flag indicating the availability of
APERF/MPERF MSRs, so that globally setting the .getavg accessor won''t
be a problem on heterogeneous configurations.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

--- 2010-05-04.orig/xen/arch/x86/acpi/cpufreq/cpufreq.c	2010-05-06
14:52:45.000000000 +0200
+++ 2010-05-04/xen/arch/x86/acpi/cpufreq/cpufreq.c	2010-05-07 10:30:33.000000000
+0200
@@ -280,7 +280,7 @@ unsigned int get_measured_perf(unsigned 
         return 0;
 
     policy = cpufreq_cpu_policy[cpu];
-    if (!policy)
+    if (!policy || !policy->aperf_mperf)
         return 0;
 
     switch (flag)
@@ -377,6 +377,26 @@ static unsigned int get_cur_freq_on_cpu(
     return freq;
 }
 
+static void feature_detect(void *info)
+{
+    struct cpufreq_policy *policy = info;
+    unsigned int eax, ecx;
+
+    ecx = cpuid_ecx(6);
+    if (ecx & CPUID_6_ECX_APERFMPERF_CAPABILITY) {
+        policy->aperf_mperf = 1;
+        acpi_cpufreq_driver.getavg = get_measured_perf;
+    }
+
+    eax = cpuid_eax(6);
+    if (eax & 0x2) {
+        policy->turbo = CPUFREQ_TURBO_ENABLED;
+        if (cpufreq_verbose)
+            printk(XENLOG_INFO "CPU%u: Turbo Mode detected and
enabled\n",
+                   smp_processor_id());
+    }
+}
+
 static unsigned int check_freqs(cpumask_t mask, unsigned int freq,
                                 struct acpi_cpufreq_data *data)
 {
@@ -615,18 +635,8 @@ acpi_cpufreq_cpu_init(struct cpufreq_pol
 
     /* Check for APERF/MPERF support in hardware
      * also check for boost support */
-    if (c->x86_vendor == X86_VENDOR_INTEL && c->cpuid_level >=
6) {
-        unsigned int ecx;
-        unsigned int eax;
-        ecx = cpuid_ecx(6);
-        if (ecx & CPUID_6_ECX_APERFMPERF_CAPABILITY)
-            acpi_cpufreq_driver.getavg = get_measured_perf;
-        eax = cpuid_eax(6);
-        if ( eax & 0x2 ) {
-            policy->turbo = CPUFREQ_TURBO_ENABLED;
-            printk(XENLOG_INFO "Turbo Mode detected and enabled!\n");
-        }
-    }
+    if (c->x86_vendor == X86_VENDOR_INTEL && c->cpuid_level >=
6)
+        on_selected_cpus(cpumask_of(cpu), feature_detect, policy, 1);
 
     /*
      * the first call to ->target() should result in us actually
--- 2010-05-04.orig/xen/arch/x86/acpi/cpufreq/powernow.c	2010-04-12
11:28:20.000000000 +0200
+++ 2010-05-04/xen/arch/x86/acpi/cpufreq/powernow.c	2010-05-07
10:30:26.000000000 +0200
@@ -165,6 +165,27 @@ static int powernow_cpufreq_verify(struc
     return cpufreq_frequency_table_verify(policy, data->freq_table);
 }
 
+static void feature_detect(void *info)
+{
+    struct cpufreq_policy *policy = info;
+    unsigned int ecx, edx;
+
+    ecx = cpuid_ecx(6);
+    if (ecx & CPUID_6_ECX_APERFMPERF_CAPABILITY) {
+        policy->aperf_mperf = 1;
+        powernow_cpufreq_driver.getavg = get_measured_perf;
+    }
+
+    edx = cpuid_edx(CPUID_FREQ_VOLT_CAPABILITIES);
+    if ((edx & CPB_CAPABLE) == CPB_CAPABLE) {
+        policy->turbo = CPUFREQ_TURBO_ENABLED;
+        if (cpufreq_verbose)
+            printk(XENLOG_INFO
+                   "CPU%u: Core Boost/Turbo detected and enabled\n",
+                   smp_processor_id());
+    }
+}
+
 static int powernow_cpufreq_cpu_init(struct cpufreq_policy *policy)
 {
     unsigned int i;
@@ -250,18 +271,8 @@ static int powernow_cpufreq_cpu_init(str
     if (result)
         goto err_freqfree;
 
-    if (c->cpuid_level >= 6) {
-        unsigned int edx;
-        unsigned int ecx;
-        ecx = cpuid_ecx(6);
-        if (ecx & CPUID_6_ECX_APERFMPERF_CAPABILITY)
-            powernow_cpufreq_driver.getavg = get_measured_perf;
-        edx = cpuid_edx(CPUID_FREQ_VOLT_CAPABILITIES);
-        if ((edx & CPB_CAPABLE) == CPB_CAPABLE) {
-            policy->turbo = CPUFREQ_TURBO_ENABLED;
-            printk(XENLOG_INFO "Core Boost/Turbo detected and
enabled\n");
-        }
-    }
+    if (c->cpuid_level >= 6)
+        on_selected_cpus(cpumask_of(cpu), feature_detect, policy, 1);
       
     /*
      * the first call to ->target() should result in us actually
--- 2010-05-04.orig/xen/include/acpi/cpufreq/cpufreq.h	2010-04-12
11:28:20.000000000 +0200
+++ 2010-05-04/xen/include/acpi/cpufreq/cpufreq.h	2010-05-07 10:22:20.000000000
+0200
@@ -52,11 +52,12 @@ struct cpufreq_policy {
                                  * governors are used */
     struct cpufreq_governor     *governor;
 
-    unsigned int        resume; /* flag for cpufreq 1st run
+    bool_t              resume; /* flag for cpufreq 1st run
                                  * S3 wakeup, hotplug cpu, etc */
-    int                 turbo;  /* tristate flag: 0 for unsupported
+    s8                  turbo;  /* tristate flag: 0 for unsupported
                                  * -1 for disable, 1 for enabled
                                  * See CPUFREQ_TURBO_* below for defines */
+    bool_t              aperf_mperf; /* CPU has APERF/MPERF MSRs */
 };
 extern struct cpufreq_policy *cpufreq_cpu_policy[NR_CPUS];
 




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