x86: kvmclock: abstract save/restore sched_clock_state

Upon resume from hibernation, CPU 0's hvclock area contains the old
values for system_time and tsc_timestamp. It is necessary for the
hypervisor to update these values with uptodate ones before the CPU uses
them.

Abstract TSC's save/restore sched_clock_state functions and use
restore_state to write to KVM_SYSTEM_TIME MSR, forcing an update.

Also move restore_sched_clock_state before __restore_processor_state,
since the later calls CONFIG_LOCK_STAT's lockstat_clock (also for TSC).
Thanks to Igor Mammedov for tracking it down.

Fixes suspend-to-disk with kvmclock.
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/include/asm/tsc.h

@@ -61,7 +61,7 @@ extern void check_tsc_sync_source(int cpu);
 extern void check_tsc_sync_target(void);
 
 extern int notsc_setup(char *);
-extern void save_sched_clock_state(void);
-extern void restore_sched_clock_state(void);
+extern void tsc_save_sched_clock_state(void);
+extern void tsc_restore_sched_clock_state(void);
 
 #endif /* _ASM_X86_TSC_H */

arch/x86/include/asm/x86_init.h

@@ -162,6 +162,8 @@ struct x86_cpuinit_ops {
  * @is_untracked_pat_range	exclude from PAT logic
  * @nmi_init			enable NMI on cpus
  * @i8042_detect		pre-detect if i8042 controller exists
+ * @save_sched_clock_state:	save state for sched_clock() on suspend
+ * @restore_sched_clock_state:	restore state for sched_clock() on resume
  */
 struct x86_platform_ops {
 	unsigned long (*calibrate_tsc)(void);
@@ -173,6 +175,8 @@ struct x86_platform_ops {
 	void (*nmi_init)(void);
 	unsigned char (*get_nmi_reason)(void);
 	int (*i8042_detect)(void);
+	void (*save_sched_clock_state)(void);
+	void (*restore_sched_clock_state)(void);
 };
 
 struct pci_dev;

arch/x86/kernel/kvmclock.c

@@ -136,6 +136,15 @@ int kvm_register_clock(char *txt)
 	return ret;
 }
 
+static void kvm_save_sched_clock_state(void)
+{
+}
+
+static void kvm_restore_sched_clock_state(void)
+{
+	kvm_register_clock("primary cpu clock, resume");
+}
+
 #ifdef CONFIG_X86_LOCAL_APIC
 static void __cpuinit kvm_setup_secondary_clock(void)
 {
@@ -195,6 +204,8 @@ void __init kvmclock_init(void)
 	x86_cpuinit.early_percpu_clock_init =
 		kvm_setup_secondary_clock;
 #endif
+	x86_platform.save_sched_clock_state = kvm_save_sched_clock_state;
+	x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state;
 	machine_ops.shutdown  = kvm_shutdown;
 #ifdef CONFIG_KEXEC
 	machine_ops.crash_shutdown  = kvm_crash_shutdown;

arch/x86/kernel/tsc.c

@@ -629,7 +629,7 @@ static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
 
 static unsigned long long cyc2ns_suspend;
 
-void save_sched_clock_state(void)
+void tsc_save_sched_clock_state(void)
 {
 	if (!sched_clock_stable)
 		return;
@@ -645,7 +645,7 @@ void save_sched_clock_state(void)
  * that sched_clock() continues from the point where it was left off during
  * suspend.
  */
-void restore_sched_clock_state(void)
+void tsc_restore_sched_clock_state(void)
 {
 	unsigned long long offset;
 	unsigned long flags;

arch/x86/kernel/x86_init.c

@@ -108,7 +108,9 @@ struct x86_platform_ops x86_platform = {
 	.is_untracked_pat_range		= is_ISA_range,
 	.nmi_init			= default_nmi_init,
 	.get_nmi_reason			= default_get_nmi_reason,
-	.i8042_detect			= default_i8042_detect
+	.i8042_detect			= default_i8042_detect,
+	.save_sched_clock_state 	= tsc_save_sched_clock_state,
+	.restore_sched_clock_state 	= tsc_restore_sched_clock_state,
 };
 
 EXPORT_SYMBOL_GPL(x86_platform);

arch/x86/power/cpu.c

@@ -114,7 +114,7 @@ static void __save_processor_state(struct saved_context *ctxt)
 void save_processor_state(void)
 {
 	__save_processor_state(&saved_context);
-	save_sched_clock_state();
+	x86_platform.save_sched_clock_state();
 }
 #ifdef CONFIG_X86_32
 EXPORT_SYMBOL(save_processor_state);
@@ -230,8 +230,8 @@ static void __restore_processor_state(struct saved_context *ctxt)
 /* Needed by apm.c */
 void restore_processor_state(void)
 {
+	x86_platform.restore_sched_clock_state();
 	__restore_processor_state(&saved_context);
-	restore_sched_clock_state();
 }
 #ifdef CONFIG_X86_32
 EXPORT_SYMBOL(restore_processor_state);