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-rw-r--r--drivers/clocksource/hyperv_timer.c23
1 files changed, 13 insertions, 10 deletions
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index 10eb5c645141..7a9030ca68c4 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -302,14 +302,6 @@ 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.
*/
u64 (*hv_read_reference_counter)(void);
@@ -380,7 +372,7 @@ static int hv_cs_enable(struct clocksource *cs)
static struct clocksource hyperv_cs_tsc = {
.name = "hyperv_clocksource_tsc_page",
- .rating = 250,
+ .rating = 500,
.read = read_hv_clock_tsc_cs,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
@@ -417,7 +409,7 @@ static u64 notrace read_hv_sched_clock_msr(void)
static struct clocksource hyperv_cs_msr = {
.name = "hyperv_clocksource_msr",
- .rating = 250,
+ .rating = 500,
.read = read_hv_clock_msr_cs,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
@@ -458,6 +450,17 @@ static bool __init hv_init_tsc_clocksource(void)
if (hv_root_partition)
return false;
+ /*
+ * If Hyper-V offers TSC_INVARIANT, then the virtualized TSC correctly
+ * handles frequency and offset changes due to live migration,
+ * pause/resume, and other VM management operations. So lower the
+ * Hyper-V Reference TSC rating, causing the generic TSC to be used.
+ * TSC_INVARIANT is not offered on ARM64, so the Hyper-V Reference
+ * TSC will be preferred over the virtualized ARM64 arch counter.
+ */
+ if (ms_hyperv.features & HV_ACCESS_TSC_INVARIANT)
+ hyperv_cs_tsc.rating = 250;
+
hv_read_reference_counter = read_hv_clock_tsc;
phys_addr = virt_to_phys(hv_get_tsc_page());