The patch is the final part of work making kvmclock stable in L2
if it works over a stable clocksource.
Signed-off-by: Denis Plotnikov <dplotnikov@xxxxxxxxxxxxx>
---
arch/x86/kernel/kvmclock.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index 52156d9..6a4d995 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -186,10 +186,22 @@ static void kvm_clock_read_with_cycles(u64 *cycles, u64 *cycles_stamp)
*cycles = __kvm_clock_read(cycles_stamp);
}
+static bool kvm_clock_stable(void)
+{
+ int cpu = get_cpu();
+ struct pvclock_vcpu_time_info *vcpu_time = &hv_clock[cpu].pvti;
+ u8 flags = pvclock_read_flags(vcpu_time);
+
+ put_cpu();
+
+ return flags & PVCLOCK_TSC_STABLE_BIT;
+}
+
struct clocksource kvm_clock = {
.name = "kvm-clock",
.read = kvm_clock_get_cycles,
.read_with_cycles = kvm_clock_read_with_cycles,
+ .is_stable = kvm_clock_stable,
.rating = 400,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
--
2.7.4
