[PATCH] pmstat: Limit hypercalls under HWP

[Jason Andryuk <jandryuk@xxxxxxxxx>]

When HWP is active, the cpufreq P-state information is not updated.  In
that case, return -ENODEV instead of bogus, incomplete info.  The xenpm
command already supports skipping results when -ENODEV is returned, so
it is re-used when -EOPNOTSUPP might be more accurate.

Similarly, set_cpufreq_para() is not applicable when HWP is active.
Many of the options already checked the governor and were inaccessible,
but SCALING_MIN/MAX_FREQ was still accessible (though it would do
nothing).  Add an ealier HWP check to handle all cases.

Signed-off-by: Jason Andryuk <jandryuk@xxxxxxxxx>
---
`xenpm get-cpufreq-states` now doesn't return any output.  It also exits
successfully since xenpm doesn't check the returns there.  Other
commands will fail:
xenpm set-scaling-maxfreq 11 1100000
failed to set scaling max freq (95 - Operation not supported)

 xen/drivers/acpi/pmstat.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/xen/drivers/acpi/pmstat.c b/xen/drivers/acpi/pmstat.c
index 85097d463c..4c4d298d1c 100644
--- a/xen/drivers/acpi/pmstat.c
+++ b/xen/drivers/acpi/pmstat.c
@@ -66,6 +66,8 @@ int do_get_pm_info(struct xen_sysctl_get_pmstat *op)
             return -ENODEV;
         if ( !cpufreq_driver.init )
             return -ENODEV;
+        if ( hwp_active() )
+            return -ENODEV;
         if ( !pmpt || !(pmpt->perf.init & XEN_PX_INIT) )
             return -EINVAL;
         break;
@@ -329,6 +331,9 @@ static int set_cpufreq_para(struct xen_sysctl_pm_op *op)
     if ( !policy || !policy->governor )
         return -EINVAL;
 
+    if ( hwp_active() )
+        return -EOPNOTSUPP;
+
     switch(op->u.set_para.ctrl_type)
     {
     case SCALING_MAX_FREQ:
-- 
2.43.0