1 files changed, 116 insertions, 68 deletions

diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index c0cef92b12b8..10356d4ec55c 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -22,12 +22,14 @@
 #include <linux/irq.h>
 #include <linux/acpi.h>
 #include <linux/hyperv.h>
+#include <linux/export.h>
 #include <clocksource/hyperv_timer.h>
-#include <asm/hyperv-tlfs.h>
+#include <hyperv/hvhdk.h>
 #include <asm/mshyperv.h>
 
 static struct clock_event_device __percpu *hv_clock_event;
-static u64 hv_sched_clock_offset __ro_after_init;
+/* Note: offset can hold negative values after hibernation. */
+static u64 hv_sched_clock_offset __read_mostly;
 
 /*
  * If false, we're using the old mechanism for stimer0 interrupts
@@ -49,7 +51,7 @@ static bool direct_mode_enabled;
 
 static int stimer0_irq = -1;
 static int stimer0_message_sint;
-static DEFINE_PER_CPU(long, stimer0_evt);
+static __maybe_unused DEFINE_PER_CPU(long, stimer0_evt);
 
 /*
  * Common code for stimer0 interrupts coming via Direct Mode or
@@ -68,7 +70,7 @@ EXPORT_SYMBOL_GPL(hv_stimer0_isr);
  * stimer0 interrupt handler for architectures that support
  * per-cpu interrupts, which also implies Direct Mode.
  */
-static irqreturn_t hv_stimer0_percpu_isr(int irq, void *dev_id)
+static irqreturn_t __maybe_unused hv_stimer0_percpu_isr(int irq, void *dev_id)
 {
 	hv_stimer0_isr();
 	return IRQ_HANDLED;
@@ -81,14 +83,14 @@ static int hv_ce_set_next_event(unsigned long delta,
 
 	current_tick = hv_read_reference_counter();
 	current_tick += delta;
-	hv_set_register(HV_REGISTER_STIMER0_COUNT, current_tick);
+	hv_set_msr(HV_MSR_STIMER0_COUNT, current_tick);
 	return 0;
 }
 
 static int hv_ce_shutdown(struct clock_event_device *evt)
 {
-	hv_set_register(HV_REGISTER_STIMER0_COUNT, 0);
-	hv_set_register(HV_REGISTER_STIMER0_CONFIG, 0);
+	hv_set_msr(HV_MSR_STIMER0_COUNT, 0);
+	hv_set_msr(HV_MSR_STIMER0_CONFIG, 0);
 	if (direct_mode_enabled && stimer0_irq >= 0)
 		disable_percpu_irq(stimer0_irq);
 
@@ -119,7 +121,7 @@ static int hv_ce_set_oneshot(struct clock_event_device *evt)
 		timer_cfg.direct_mode = 0;
 		timer_cfg.sintx = stimer0_message_sint;
 	}
-	hv_set_register(HV_REGISTER_STIMER0_CONFIG, timer_cfg.as_uint64);
+	hv_set_msr(HV_MSR_STIMER0_CONFIG, timer_cfg.as_uint64);
 	return 0;
 }
 
@@ -137,7 +139,21 @@ static int hv_stimer_init(unsigned int cpu)
 	ce->name = "Hyper-V clockevent";
 	ce->features = CLOCK_EVT_FEAT_ONESHOT;
 	ce->cpumask = cpumask_of(cpu);
-	ce->rating = 1000;
+
+	/*
+	 * Lower the rating of the Hyper-V timer in a TDX VM without paravisor,
+	 * so the local APIC timer (lapic_clockevent) is the default timer in
+	 * such a VM. The Hyper-V timer is not preferred in such a VM because
+	 * it depends on the slow VM Reference Counter MSR (the Hyper-V TSC
+	 * page is not enbled in such a VM because the VM uses Invariant TSC
+	 * as a better clocksource and it's challenging to mark the Hyper-V
+	 * TSC page shared in very early boot).
+	 */
+	if (!ms_hyperv.paravisor_present && hv_isolation_type_tdx())
+		ce->rating = 90;
+	else
+		ce->rating = 1000;
+
 	ce->set_state_shutdown = hv_ce_shutdown;
 	ce->set_state_oneshot = hv_ce_set_oneshot;
 	ce->set_next_event = hv_ce_set_next_event;
@@ -196,6 +212,7 @@ void __weak hv_remove_stimer0_handler(void)
 {
 };
 
+#ifdef CONFIG_ACPI
 /* Called only on architectures with per-cpu IRQs (i.e., not x86/x64) */
 static int hv_setup_stimer0_irq(void)
 {
@@ -230,6 +247,16 @@ static void hv_remove_stimer0_irq(void)
 		stimer0_irq = -1;
 	}
 }
+#else
+static int hv_setup_stimer0_irq(void)
+{
+	return 0;
+}
+
+static void hv_remove_stimer0_irq(void)
+{
+}
+#endif
 
 /* hv_stimer_alloc - Global initialization of the clockevent and stimer0 */
 int hv_stimer_alloc(bool have_percpu_irqs)
@@ -354,6 +381,20 @@ void hv_stimer_global_cleanup(void)
 }
 EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
 
+static __always_inline u64 read_hv_clock_msr(void)
+{
+	/*
+	 * Read the partition counter to get the current tick count. This count
+	 * is set to 0 when the partition is created and is incremented in 100
+	 * nanosecond units.
+	 *
+	 * Use hv_raw_get_msr() because this function is used from
+	 * noinstr. Notable; while HV_MSR_TIME_REF_COUNT is a synthetic
+	 * register it doesn't need the GHCB path.
+	 */
+	return hv_raw_get_msr(HV_MSR_TIME_REF_COUNT);
+}
+
 /*
  * Code and definitions for the Hyper-V clocksources.  Two
  * clocksources are defined: one that reads the Hyper-V defined MSR, and
@@ -365,7 +406,7 @@ EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
 static union {
 	struct ms_hyperv_tsc_page page;
 	u8 reserved[PAGE_SIZE];
-} tsc_pg __aligned(PAGE_SIZE);
+} tsc_pg __bss_decrypted __aligned(PAGE_SIZE);
 
 static struct ms_hyperv_tsc_page *tsc_page = &tsc_pg.page;
 static unsigned long tsc_pfn;
@@ -382,14 +423,20 @@ struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
 }
 EXPORT_SYMBOL_GPL(hv_get_tsc_page);
 
-static u64 notrace read_hv_clock_tsc(void)
+static __always_inline u64 read_hv_clock_tsc(void)
 {
-	u64 current_tick = hv_read_tsc_page(hv_get_tsc_page());
+	u64 cur_tsc, time;
 
-	if (current_tick == U64_MAX)
-		current_tick = hv_get_register(HV_REGISTER_TIME_REF_COUNT);
+	/*
+	 * The Hyper-V Top-Level Function Spec (TLFS), section Timers,
+	 * subsection Refererence Counter, guarantees that the TSC and MSR
+	 * times are in sync and monotonic. Therefore we can fall back
+	 * to the MSR in case the TSC page indicates unavailability.
+	 */
+	if (!hv_read_tsc_page_tsc(tsc_page, &cur_tsc, &time))
+		time = read_hv_clock_msr();
 
-	return current_tick;
+	return time;
 }
 
 static u64 notrace read_hv_clock_tsc_cs(struct clocksource *arg)
@@ -397,7 +444,7 @@ static u64 notrace read_hv_clock_tsc_cs(struct clocksource *arg)
 	return read_hv_clock_tsc();
 }
 
-static u64 notrace read_hv_sched_clock_tsc(void)
+static u64 noinstr read_hv_sched_clock_tsc(void)
 {
 	return (read_hv_clock_tsc() - hv_sched_clock_offset) *
 		(NSEC_PER_SEC / HV_CLOCK_HZ);
@@ -408,9 +455,9 @@ static void suspend_hv_clock_tsc(struct clocksource *arg)
 	union hv_reference_tsc_msr tsc_msr;
 
 	/* Disable the TSC page */
-	tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);
+	tsc_msr.as_uint64 = hv_get_msr(HV_MSR_REFERENCE_TSC);
 	tsc_msr.enable = 0;
-	hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);
+	hv_set_msr(HV_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 }
 
 
@@ -419,10 +466,21 @@ static void resume_hv_clock_tsc(struct clocksource *arg)
 	union hv_reference_tsc_msr tsc_msr;
 
 	/* Re-enable the TSC page */
-	tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);
+	tsc_msr.as_uint64 = hv_get_msr(HV_MSR_REFERENCE_TSC);
 	tsc_msr.enable = 1;
 	tsc_msr.pfn = tsc_pfn;
-	hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);
+	hv_set_msr(HV_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
+}
+
+/*
+ * Called during resume from hibernation, from overridden
+ * x86_platform.restore_sched_clock_state routine. This is to adjust offsets
+ * used to calculate time for hv tsc page based sched_clock, to account for
+ * time spent before hibernation.
+ */
+void hv_adj_sched_clock_offset(u64 offset)
+{
+	hv_sched_clock_offset -= offset;
 }
 
 #ifdef HAVE_VDSO_CLOCKMODE_HVCLOCK
@@ -449,30 +507,14 @@ static struct clocksource hyperv_cs_tsc = {
 #endif
 };
 
-static u64 notrace read_hv_clock_msr(void)
-{
-	/*
-	 * Read the partition counter to get the current tick count. This count
-	 * is set to 0 when the partition is created and is incremented in
-	 * 100 nanosecond units.
-	 */
-	return hv_get_register(HV_REGISTER_TIME_REF_COUNT);
-}
-
 static u64 notrace read_hv_clock_msr_cs(struct clocksource *arg)
 {
 	return read_hv_clock_msr();
 }
 
-static u64 notrace read_hv_sched_clock_msr(void)
-{
-	return (read_hv_clock_msr() - hv_sched_clock_offset) *
-		(NSEC_PER_SEC / HV_CLOCK_HZ);
-}
-
 static struct clocksource hyperv_cs_msr = {
 	.name	= "hyperv_clocksource_msr",
-	.rating	= 500,
+	.rating	= 495,
 	.read	= read_hv_clock_msr_cs,
 	.mask	= CLOCKSOURCE_MASK(64),
 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
@@ -502,29 +544,34 @@ static __always_inline void hv_setup_sched_clock(void *sched_clock)
 static __always_inline void hv_setup_sched_clock(void *sched_clock) {}
 #endif /* CONFIG_GENERIC_SCHED_CLOCK */
 
-static bool __init hv_init_tsc_clocksource(void)
+static void __init hv_init_tsc_clocksource(void)
 {
 	union hv_reference_tsc_msr tsc_msr;
 
-	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
-		return false;
-
 	/*
+	 * When running as a guest partition:
+	 *
 	 * 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.
-	 * While the Hyper-V MSR clocksource won't be used since the
-	 * Reference TSC clocksource is present, change its rating as
-	 * well for consistency.
+	 *
+	 * When running as the root partition:
+	 *
+	 * There is no HV_ACCESS_TSC_INVARIANT feature. Always lower the rating
+	 * of the Hyper-V Reference TSC.
 	 */
-	if (ms_hyperv.features & HV_ACCESS_TSC_INVARIANT) {
+	if ((ms_hyperv.features & HV_ACCESS_TSC_INVARIANT) ||
+	    hv_root_partition()) {
 		hyperv_cs_tsc.rating = 250;
-		hyperv_cs_msr.rating = 250;
+		hyperv_cs_msr.rating = 245;
 	}
 
+	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
+		return;
+
 	hv_read_reference_counter = read_hv_clock_tsc;
 
 	/*
@@ -543,44 +590,45 @@ static bool __init hv_init_tsc_clocksource(void)
 	 * thus TSC clocksource will work even without the real TSC page
 	 * mapped.
 	 */
-	tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);
-	if (hv_root_partition)
+	tsc_msr.as_uint64 = hv_get_msr(HV_MSR_REFERENCE_TSC);
+	if (hv_root_partition())
 		tsc_pfn = tsc_msr.pfn;
 	else
 		tsc_pfn = HVPFN_DOWN(virt_to_phys(tsc_page));
 	tsc_msr.enable = 1;
 	tsc_msr.pfn = tsc_pfn;
-	hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);
+	hv_set_msr(HV_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 
 	clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
 
-	hv_sched_clock_offset = hv_read_reference_counter();
-	hv_setup_sched_clock(read_hv_sched_clock_tsc);
-
-	return true;
+	/*
+	 * If TSC is invariant, then let it stay as the sched clock since it
+	 * will be faster than reading the TSC page. But if not invariant, use
+	 * the TSC page so that live migrations across hosts with different
+	 * frequencies is handled correctly.
+	 */
+	if (!(ms_hyperv.features & HV_ACCESS_TSC_INVARIANT)) {
+		hv_sched_clock_offset = hv_read_reference_counter();
+		hv_setup_sched_clock(read_hv_sched_clock_tsc);
+	}
 }
 
 void __init hv_init_clocksource(void)
 {
 	/*
-	 * Try to set up the TSC page clocksource. If it succeeds, we're
-	 * done. Otherwise, set up the MSR clocksource.  At least one of
-	 * these will always be available except on very old versions of
-	 * Hyper-V on x86.  In that case we won't have a Hyper-V
+	 * Try to set up the TSC page clocksource, then the MSR clocksource.
+	 * At least one of these will always be available except on very old
+	 * versions of Hyper-V on x86.  In that case we won't have a Hyper-V
 	 * clocksource, but Linux will still run with a clocksource based
 	 * on the emulated PIT or LAPIC timer.
+	 *
+	 * Never use the MSR clocksource as sched clock.  It's too slow.
+	 * Better to use the native sched clock as the fallback.
 	 */
-	if (hv_init_tsc_clocksource())
-		return;
-
-	if (!(ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE))
-		return;
-
-	hv_read_reference_counter = read_hv_clock_msr;
-	clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
+	hv_init_tsc_clocksource();
 
-	hv_sched_clock_offset = hv_read_reference_counter();
-	hv_setup_sched_clock(read_hv_sched_clock_msr);
+	if (ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE)
+		clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
 }
 
 void __init hv_remap_tsc_clocksource(void)
@@ -588,7 +636,7 @@ void __init hv_remap_tsc_clocksource(void)
 	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
 		return;
 
-	if (!hv_root_partition) {
+	if (!hv_root_partition()) {
 		WARN(1, "%s: attempt to remap TSC page in guest partition\n",
 		     __func__);
 		return;