cpufreq: xen is default cpufreq, userspace is default governor (override on cmdline)

Set userspace governor as default, which stays same effect
as when cpufreq in xen is not enabled. As a result, enable cpufreq
in xen by default to avoid reboot to activate cpufreq. Now it's
always on but w/o performance impact if user doesn't attempt
to change governor.

Add governor option at cmdline, add some warning info for debug.

Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>

2 files changed, 19 insertions, 2 deletions

diff --git a/xen/drivers/cpufreq/cpufreq.c b/xen/drivers/cpufreq/cpufreq.c
index 169426e373..dee38fa513 100644
--- a/xen/drivers/cpufreq/cpufreq.c
+++ b/xen/drivers/cpufreq/cpufreq.c
@@ -214,8 +214,20 @@ int cpufreq_add_cpu(unsigned int cpu)
         memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
         policy->governor = NULL;
         ret = __cpufreq_set_policy(policy, &new_policy);
-        if (ret)
-            goto err2;
+        if (ret) {
+            if (new_policy.governor == CPUFREQ_DEFAULT_GOVERNOR)
+                /* if default governor fail, cpufreq really meet troubles */
+                goto err2;
+            else {
+                /* grub option governor fail */
+                /* give one more chance to default gov */
+                memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
+                new_policy.governor = CPUFREQ_DEFAULT_GOVERNOR;
+                ret = __cpufreq_set_policy(policy, &new_policy);
+                if (ret)
+                    goto err2;
+            }
+        }
     }
 
     return 0;
diff --git a/xen/drivers/cpufreq/utility.c b/xen/drivers/cpufreq/utility.c
index 1c8176fabe..4ac3833923 100644
--- a/xen/drivers/cpufreq/utility.c
+++ b/xen/drivers/cpufreq/utility.c
@@ -360,10 +360,15 @@ int __cpufreq_set_policy(struct cpufreq_policy *data,
         /* start new governor */
         data->governor = policy->governor;
         if (__cpufreq_governor(data, CPUFREQ_GOV_START)) {
+            printk(KERN_WARNING "Fail change to %s governor\n",
+                                 data->governor->name);
+
             /* new governor failed, so re-start old one */
             if (old_gov) {
                 data->governor = old_gov;
                 __cpufreq_governor(data, CPUFREQ_GOV_START);
+                printk(KERN_WARNING "Still stay at %s governor\n",
+                                     data->governor->name);
             }
             return -EINVAL;
         }