1 files changed, 65 insertions, 19 deletions

diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index 287d8d58c21a..9d808d595ca8 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -66,7 +66,7 @@ static int hv_ce_set_next_event(unsigned long delta,
 {
 	u64 current_tick;
 
-	current_tick = hyperv_cs->read(NULL);
+	current_tick = hv_read_reference_counter();
 	current_tick += delta;
 	hv_init_timer(0, current_tick);
 	return 0;
@@ -302,22 +302,33 @@ 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;
-EXPORT_SYMBOL_GPL(hyperv_cs);
+u64 (*hv_read_reference_counter)(void);
+EXPORT_SYMBOL_GPL(hv_read_reference_counter);
 
-static struct ms_hyperv_tsc_page tsc_pg __aligned(PAGE_SIZE);
+static union {
+	struct ms_hyperv_tsc_page page;
+	u8 reserved[PAGE_SIZE];
+} tsc_pg __aligned(PAGE_SIZE);
 
 struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
 {
-	return &tsc_pg;
+	return &tsc_pg.page;
 }
 EXPORT_SYMBOL_GPL(hv_get_tsc_page);
 
-static u64 notrace read_hv_clock_tsc(struct clocksource *arg)
+static u64 notrace read_hv_clock_tsc(void)
 {
-	u64 current_tick = hv_read_tsc_page(&tsc_pg);
+	u64 current_tick = hv_read_tsc_page(hv_get_tsc_page());
 
 	if (current_tick == U64_MAX)
 		hv_get_time_ref_count(current_tick);
@@ -325,20 +336,50 @@ static u64 notrace read_hv_clock_tsc(struct clocksource *arg)
 	return current_tick;
 }
 
+static u64 notrace read_hv_clock_tsc_cs(struct clocksource *arg)
+{
+	return read_hv_clock_tsc();
+}
+
 static u64 read_hv_sched_clock_tsc(void)
 {
-	return read_hv_clock_tsc(NULL) - hv_sched_clock_offset;
+	return read_hv_clock_tsc() - hv_sched_clock_offset;
+}
+
+static void suspend_hv_clock_tsc(struct clocksource *arg)
+{
+	u64 tsc_msr;
+
+	/* Disable the TSC page */
+	hv_get_reference_tsc(tsc_msr);
+	tsc_msr &= ~BIT_ULL(0);
+	hv_set_reference_tsc(tsc_msr);
+}
+
+
+static void resume_hv_clock_tsc(struct clocksource *arg)
+{
+	phys_addr_t phys_addr = virt_to_phys(&tsc_pg);
+	u64 tsc_msr;
+
+	/* Re-enable the TSC page */
+	hv_get_reference_tsc(tsc_msr);
+	tsc_msr &= GENMASK_ULL(11, 0);
+	tsc_msr |= BIT_ULL(0) | (u64)phys_addr;
+	hv_set_reference_tsc(tsc_msr);
 }
 
 static struct clocksource hyperv_cs_tsc = {
 	.name	= "hyperv_clocksource_tsc_page",
-	.rating	= 400,
-	.read	= read_hv_clock_tsc,
+	.rating	= 250,
+	.read	= read_hv_clock_tsc_cs,
 	.mask	= CLOCKSOURCE_MASK(64),
 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+	.suspend= suspend_hv_clock_tsc,
+	.resume	= resume_hv_clock_tsc,
 };
 
-static u64 notrace read_hv_clock_msr(struct clocksource *arg)
+static u64 notrace read_hv_clock_msr(void)
 {
 	u64 current_tick;
 	/*
@@ -350,15 +391,20 @@ static u64 notrace read_hv_clock_msr(struct clocksource *arg)
 	return current_tick;
 }
 
+static u64 notrace read_hv_clock_msr_cs(struct clocksource *arg)
+{
+	return read_hv_clock_msr();
+}
+
 static u64 read_hv_sched_clock_msr(void)
 {
-	return read_hv_clock_msr(NULL) - hv_sched_clock_offset;
+	return read_hv_clock_msr() - hv_sched_clock_offset;
 }
 
 static struct clocksource hyperv_cs_msr = {
 	.name	= "hyperv_clocksource_msr",
-	.rating	= 400,
-	.read	= read_hv_clock_msr,
+	.rating	= 250,
+	.read	= read_hv_clock_msr_cs,
 	.mask	= CLOCKSOURCE_MASK(64),
 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
 };
@@ -371,8 +417,8 @@ static bool __init hv_init_tsc_clocksource(void)
 	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
 		return false;
 
-	hyperv_cs = &hyperv_cs_tsc;
-	phys_addr = virt_to_phys(&tsc_pg);
+	hv_read_reference_counter = read_hv_clock_tsc;
+	phys_addr = virt_to_phys(hv_get_tsc_page());
 
 	/*
 	 * The Hyper-V TLFS specifies to preserve the value of reserved
@@ -389,7 +435,7 @@ static bool __init hv_init_tsc_clocksource(void)
 	hv_set_clocksource_vdso(hyperv_cs_tsc);
 	clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
 
-	hv_sched_clock_offset = hyperv_cs->read(hyperv_cs);
+	hv_sched_clock_offset = hv_read_reference_counter();
 	hv_setup_sched_clock(read_hv_sched_clock_tsc);
 
 	return true;
@@ -411,10 +457,10 @@ void __init hv_init_clocksource(void)
 	if (!(ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE))
 		return;
 
-	hyperv_cs = &hyperv_cs_msr;
+	hv_read_reference_counter = read_hv_clock_msr;
 	clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
 
-	hv_sched_clock_offset = hyperv_cs->read(hyperv_cs);
+	hv_sched_clock_offset = hv_read_reference_counter();
 	hv_setup_sched_clock(read_hv_sched_clock_msr);
 }
 EXPORT_SYMBOL_GPL(hv_init_clocksource);