@@ -302,6 +302,14 @@ EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
* the other that uses the TSC reference page feature as defined in the
* TLFS. The MSR version is for compatibility with old versions of
* Hyper-V and 32-bit x86. The TSC reference page version is preferred.
+ *
+ * The Hyper-V clocksource ratings of 250 are chosen to be below the
+ * TSC clocksource rating of 300. In configurations where Hyper-V offers
+ * an InvariantTSC, the TSC is not marked "unstable", so the TSC clocksource
+ * is available and preferred. With the higher rating, it will be the
+ * default. On older hardware and Hyper-V versions, the TSC is marked
+ * "unstable", so no TSC clocksource is created and the selected Hyper-V
+ * clocksource will be the default.
*/
struct clocksource *hyperv_cs;
@@ -356,7 +364,7 @@ static void resume_hv_clock_tsc(struct clocksource *arg)
static struct clocksource hyperv_cs_tsc = {
.name = "hyperv_clocksource_tsc_page",
- .rating = 400,
+ .rating = 250,
.read = read_hv_clock_tsc,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
@@ -384,7 +392,7 @@ static u64 read_hv_sched_clock_msr(void)
static struct clocksource hyperv_cs_msr = {
.name = "hyperv_clocksource_msr",
- .rating = 400,
+ .rating = 250,
.read = read_hv_clock_msr,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,