[PATCH v2 01/13] cpufreq: Allow restricting to internal governors only

[Jason Andryuk <jandryuk@xxxxxxxxx>]

For hwp, the standard governors are not usable, and only the internal
one is applicable.  Add the cpufreq_governor_internal boolean to
indicate when an internal governor, like hwp-internal, will be used.
This is set during presmp_initcall, so that it can suppress governor
registration during initcall.  Only a governor with a name containing
"-internal" will be allowed in that case.

This way, the unuseable governors are not registered, so they internal
one is the only one returned to userspace.  This means incompatible
governors won't be advertised to userspace.

Signed-off-by: Jason Andryuk <jandryuk@xxxxxxxxx>
---
v2:
Switch to "-internal"
Add blank line in header
---
 xen/drivers/cpufreq/cpufreq.c      | 5 +++++
 xen/include/acpi/cpufreq/cpufreq.h | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/xen/drivers/cpufreq/cpufreq.c b/xen/drivers/cpufreq/cpufreq.c
index a94520ee57..1fdd63d7b5 100644
--- a/xen/drivers/cpufreq/cpufreq.c
+++ b/xen/drivers/cpufreq/cpufreq.c
@@ -57,6 +57,7 @@ struct cpufreq_dom {
 };
 static LIST_HEAD_READ_MOSTLY(cpufreq_dom_list_head);
 
+bool __read_mostly cpufreq_governor_internal;
 struct cpufreq_governor *__read_mostly cpufreq_opt_governor;
 LIST_HEAD_READ_MOSTLY(cpufreq_governor_list);
 
@@ -122,6 +123,10 @@ int __init cpufreq_register_governor(struct 
cpufreq_governor *governor)
     if (!governor)
         return -EINVAL;
 
+    if (cpufreq_governor_internal &&
+        strstr(governor->name, "-internal") == NULL)
+        return -EINVAL;
+
     if (__find_governor(governor->name) != NULL)
         return -EEXIST;
 
diff --git a/xen/include/acpi/cpufreq/cpufreq.h 
b/xen/include/acpi/cpufreq/cpufreq.h
index 35dcf21e8f..0da32ef519 100644
--- a/xen/include/acpi/cpufreq/cpufreq.h
+++ b/xen/include/acpi/cpufreq/cpufreq.h
@@ -114,6 +114,8 @@ extern struct cpufreq_governor cpufreq_gov_userspace;
 extern struct cpufreq_governor cpufreq_gov_performance;
 extern struct cpufreq_governor cpufreq_gov_powersave;
 
+extern bool cpufreq_governor_internal;
+
 extern struct list_head cpufreq_governor_list;
 
 extern int cpufreq_register_governor(struct cpufreq_governor *governor);
-- 
2.37.1