x86: pvclock: introduce helper to read flags
Acked-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
index 47e25d4..ea27a8d 100644
--- a/arch/x86/include/asm/pvclock.h
+++ b/arch/x86/include/asm/pvclock.h
@@ -6,6 +6,7 @@
/* some helper functions for xen and kvm pv clock sources */
cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
+u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
void pvclock_set_flags(u8 flags);
unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
index a7d9091..c8fb043 100644
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -45,6 +45,19 @@
atomic64_set(&last_value, 0);
}
+u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src)
+{
+ unsigned version;
+ cycle_t ret;
+ u8 flags;
+
+ do {
+ version = __pvclock_read_cycles(src, &ret, &flags);
+ } while ((src->version & 1) || version != src->version);
+
+ return flags & valid_flags;
+}
+
cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src)
{
unsigned version;