[Xen-devel] [PATCH] x86: fix MWAIT-based idle driver for CPUs without ARAT

["Jan Beulich" <JBeulich@xxxxxxxx>]

lapic_timer_{on,off} need to get initialized in this case. This in turn
requires getting HPET broadcast setup to be carried out earlier (and
hence preventing double initialization there).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Note that I don't have a respective system available to test these
adjustments (which is also why I didn't notice the omission from the
original patch), so I can only hope that this works and takes care of
the observed boot failure.

--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -74,6 +74,29 @@ static void lapic_timer_nop(void) { }
 void (*__read_mostly lapic_timer_off)(void);
 void (*__read_mostly lapic_timer_on)(void);
 
+bool_t lapic_timer_init(void)
+{
+    if ( boot_cpu_has(X86_FEATURE_ARAT) )
+    {
+        lapic_timer_off = lapic_timer_nop;
+        lapic_timer_on = lapic_timer_nop;
+    }
+    else if ( hpet_broadcast_is_available() )
+    {
+        lapic_timer_off = hpet_broadcast_enter;
+        lapic_timer_on = hpet_broadcast_exit;
+    }
+    else if ( pit_broadcast_is_available() )
+    {
+        lapic_timer_off = pit_broadcast_enter;
+        lapic_timer_on = pit_broadcast_exit;
+    }
+    else
+        return 0;
+
+    return 1;
+}
+
 static uint64_t (*__read_mostly tick_to_ns)(uint64_t) = acpi_pm_tick_to_ns;
 
 void (*__read_mostly pm_idle_save)(void);
@@ -789,25 +812,8 @@ static int check_cx(struct acpi_processo
         if ( local_apic_timer_c2_ok )
             break;
     case ACPI_STATE_C3:
-        if ( boot_cpu_has(X86_FEATURE_ARAT) )
-        {
-            lapic_timer_off = lapic_timer_nop;
-            lapic_timer_on = lapic_timer_nop;
-        }
-        else if ( hpet_broadcast_is_available() )
-        {
-            lapic_timer_off = hpet_broadcast_enter;
-            lapic_timer_on = hpet_broadcast_exit;
-        }
-        else if ( pit_broadcast_is_available() )
-        {
-            lapic_timer_off = pit_broadcast_enter;
-            lapic_timer_on = pit_broadcast_exit;
-        }
-        else
-        {
+        if ( !lapic_timer_init() )
             return -EINVAL;
-        }
 
         /* All the logic here assumes flags.bm_check is same across all CPUs */
         if ( bm_check_flag == -1 )
--- a/xen/arch/x86/cpu/mwait-idle.c
+++ b/xen/arch/x86/cpu/mwait-idle.c
@@ -56,6 +56,7 @@
 #include <xen/softirq.h>
 #include <xen/trace.h>
 #include <asm/cpuidle.h>
+#include <asm/hpet.h>
 #include <asm/mwait.h>
 #include <asm/msr.h>
 #include <acpi/cpufreq/cpufreq.h>
@@ -501,6 +502,12 @@ int __init mwait_idle_init(struct notifi
 
        err = mwait_idle_probe();
        if (!err) {
+               if (!boot_cpu_has(X86_FEATURE_ARAT))
+                       hpet_broadcast_init();
+               if (!lapic_timer_init())
+                       err = -EINVAL;
+       }
+       if (!err) {
                nfb->notifier_call = mwait_idle_cpu_init;
                mwait_idle_cpu_init(nfb, CPU_UP_PREPARE, NULL);
 
--- a/xen/arch/x86/hpet.c
+++ b/xen/arch/x86/hpet.c
@@ -495,7 +495,7 @@ void __init hpet_broadcast_init(void)
     u32 hpet_id, cfg;
     unsigned int i, n;
 
-    if ( hpet_rate == 0 )
+    if ( hpet_rate == 0 || hpet_broadcast_is_available() )
         return;
 
     cfg = hpet_read32(HPET_CFG);
--- a/xen/include/asm-x86/cpuidle.h
+++ b/xen/include/asm-x86/cpuidle.h
@@ -10,6 +10,7 @@ extern struct acpi_processor_power *proc
 
 extern void (*pm_idle_save)(void);
 
+bool_t lapic_timer_init(void);
 extern void (*lapic_timer_off)(void);
 extern void (*lapic_timer_on)(void);

Attachment: x86-mwait-idle-lapic-timer-init.patch
Description: Text document

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