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, will be used.  This is set
during presmp_initcall, and governor registration can be skipped when
called during initcall.

This way unusable governors are not registered, and only compatible
governors are advertised to userspace.

Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---
v6:
Add Jan's Ack

v5:
Check cpufreq_governor_internal and skip registration as applicable
Remove internal flag

v4:
Rework to use an internal flag
Removed Jan's Ack since the approach is different.

v3:
Switch to initdata
Add Jan Acked-by
Commit message s/they/the/ typo
Don't register hwp-internal when running non-hwp - Marek

v2:
Switch to "-internal"
Add blank line in header
---
 xen/drivers/cpufreq/cpufreq.c                | 1 +
 xen/drivers/cpufreq/cpufreq_misc_governors.c | 9 +++++++++
 xen/drivers/cpufreq/cpufreq_ondemand.c       | 3 +++
 xen/include/acpi/cpufreq/cpufreq.h           | 2 ++
 4 files changed, 15 insertions(+)

diff --git a/xen/drivers/cpufreq/cpufreq.c b/xen/drivers/cpufreq/cpufreq.c
index 2321c7dd07..67a58d409b 100644
--- a/xen/drivers/cpufreq/cpufreq.c
+++ b/xen/drivers/cpufreq/cpufreq.c
@@ -56,6 +56,7 @@ struct cpufreq_dom {
 };
 static LIST_HEAD_READ_MOSTLY(cpufreq_dom_list_head);
 
+bool __initdata cpufreq_governor_internal;
 struct cpufreq_governor *__read_mostly cpufreq_opt_governor;
 LIST_HEAD_READ_MOSTLY(cpufreq_governor_list);
 
diff --git a/xen/drivers/cpufreq/cpufreq_misc_governors.c b/xen/drivers/cpufreq/cpufreq_misc_governors.c
index f5571f5486..0327fad23b 100644
--- a/xen/drivers/cpufreq/cpufreq_misc_governors.c
+++ b/xen/drivers/cpufreq/cpufreq_misc_governors.c
@@ -120,6 +120,9 @@ static int __init cf_check cpufreq_gov_userspace_init(void)
 {
     unsigned int cpu;
 
+    if ( cpufreq_governor_internal )
+        return 0;
+
     for_each_online_cpu(cpu)
         per_cpu(cpu_set_freq, cpu) = userspace_cmdline_freq;
     register_cpu_notifier(&cpufreq_userspace_cpu_nfb);
@@ -162,6 +165,9 @@ struct cpufreq_governor cpufreq_gov_performance = {
 
 static int __init cf_check cpufreq_gov_performance_init(void)
 {
+    if ( cpufreq_governor_internal )
+        return 0;
+
     return cpufreq_register_governor(&cpufreq_gov_performance);
 }
 __initcall(cpufreq_gov_performance_init);
@@ -201,6 +207,9 @@ struct cpufreq_governor cpufreq_gov_powersave = {
 
 static int __init cf_check cpufreq_gov_powersave_init(void)
 {
+    if ( cpufreq_governor_internal )
+        return 0;
+
     return cpufreq_register_governor(&cpufreq_gov_powersave);
 }
 __initcall(cpufreq_gov_powersave_init);
diff --git a/xen/drivers/cpufreq/cpufreq_ondemand.c b/xen/drivers/cpufreq/cpufreq_ondemand.c
index fbcd14d6c3..06cfc88d30 100644
--- a/xen/drivers/cpufreq/cpufreq_ondemand.c
+++ b/xen/drivers/cpufreq/cpufreq_ondemand.c
@@ -360,6 +360,9 @@ struct cpufreq_governor cpufreq_gov_dbs = {
 
 static int __init cf_check cpufreq_gov_dbs_init(void)
 {
+    if ( cpufreq_governor_internal )
+        return 0;
+
     return cpufreq_register_governor(&cpufreq_gov_dbs);
 }
 __initcall(cpufreq_gov_dbs_init);
diff --git a/xen/include/acpi/cpufreq/cpufreq.h b/xen/include/acpi/cpufreq/cpufreq.h
index 35dcf21e8f..44fc4c58fc 100644
--- a/xen/include/acpi/cpufreq/cpufreq.h
+++ b/xen/include/acpi/cpufreq/cpufreq.h
@@ -116,6 +116,8 @@ extern struct cpufreq_governor cpufreq_gov_powersave;
 
 extern struct list_head cpufreq_governor_list;
 
+extern bool cpufreq_governor_internal;
+
 extern int cpufreq_register_governor(struct cpufreq_governor *governor);
 extern struct cpufreq_governor *__find_governor(const char *governor);
 #define CPUFREQ_DEFAULT_GOVERNOR &cpufreq_gov_dbs
-- 
2.41.0