1 files changed, 594 insertions, 0 deletions

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
new file mode 100644
index 000000000..9809de9f2
--- /dev/null
+++ b/arch/x86/xen/time.c
@@ -0,0 +1,594 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Xen time implementation.
+ *
+ * This is implemented in terms of a clocksource driver which uses
+ * the hypervisor clock as a nanosecond timebase, and a clockevent
+ * driver which uses the hypervisor's timer mechanism.
+ *
+ * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
+ */
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#include <linux/pvclock_gtod.h>
+#include <linux/timekeeper_internal.h>
+
+#include <asm/pvclock.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/xen/hypercall.h>
+
+#include <xen/events.h>
+#include <xen/features.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/vcpu.h>
+
+#include "xen-ops.h"
+
+/* Xen may fire a timer up to this many ns early */
+#define TIMER_SLOP	100000
+
+static u64 xen_sched_clock_offset __read_mostly;
+
+/* Get the TSC speed from Xen */
+static unsigned long xen_tsc_khz(void)
+{
+	struct pvclock_vcpu_time_info *info =
+		&HYPERVISOR_shared_info->vcpu_info[0].time;
+
+	return pvclock_tsc_khz(info);
+}
+
+static u64 xen_clocksource_read(void)
+{
+        struct pvclock_vcpu_time_info *src;
+	u64 ret;
+
+	preempt_disable_notrace();
+	src = &__this_cpu_read(xen_vcpu)->time;
+	ret = pvclock_clocksource_read(src);
+	preempt_enable_notrace();
+	return ret;
+}
+
+static u64 xen_clocksource_get_cycles(struct clocksource *cs)
+{
+	return xen_clocksource_read();
+}
+
+static u64 xen_sched_clock(void)
+{
+	return xen_clocksource_read() - xen_sched_clock_offset;
+}
+
+static void xen_read_wallclock(struct timespec64 *ts)
+{
+	struct shared_info *s = HYPERVISOR_shared_info;
+	struct pvclock_wall_clock *wall_clock = &(s->wc);
+        struct pvclock_vcpu_time_info *vcpu_time;
+
+	vcpu_time = &get_cpu_var(xen_vcpu)->time;
+	pvclock_read_wallclock(wall_clock, vcpu_time, ts);
+	put_cpu_var(xen_vcpu);
+}
+
+static void xen_get_wallclock(struct timespec64 *now)
+{
+	xen_read_wallclock(now);
+}
+
+static int xen_set_wallclock(const struct timespec64 *now)
+{
+	return -ENODEV;
+}
+
+static int xen_pvclock_gtod_notify(struct notifier_block *nb,
+				   unsigned long was_set, void *priv)
+{
+	/* Protected by the calling core code serialization */
+	static struct timespec64 next_sync;
+
+	struct xen_platform_op op;
+	struct timespec64 now;
+	struct timekeeper *tk = priv;
+	static bool settime64_supported = true;
+	int ret;
+
+	now.tv_sec = tk->xtime_sec;
+	now.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
+
+	/*
+	 * We only take the expensive HV call when the clock was set
+	 * or when the 11 minutes RTC synchronization time elapsed.
+	 */
+	if (!was_set && timespec64_compare(&now, &next_sync) < 0)
+		return NOTIFY_OK;
+
+again:
+	if (settime64_supported) {
+		op.cmd = XENPF_settime64;
+		op.u.settime64.mbz = 0;
+		op.u.settime64.secs = now.tv_sec;
+		op.u.settime64.nsecs = now.tv_nsec;
+		op.u.settime64.system_time = xen_clocksource_read();
+	} else {
+		op.cmd = XENPF_settime32;
+		op.u.settime32.secs = now.tv_sec;
+		op.u.settime32.nsecs = now.tv_nsec;
+		op.u.settime32.system_time = xen_clocksource_read();
+	}
+
+	ret = HYPERVISOR_platform_op(&op);
+
+	if (ret == -ENOSYS && settime64_supported) {
+		settime64_supported = false;
+		goto again;
+	}
+	if (ret < 0)
+		return NOTIFY_BAD;
+
+	/*
+	 * Move the next drift compensation time 11 minutes
+	 * ahead. That's emulating the sync_cmos_clock() update for
+	 * the hardware RTC.
+	 */
+	next_sync = now;
+	next_sync.tv_sec += 11 * 60;
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block xen_pvclock_gtod_notifier = {
+	.notifier_call = xen_pvclock_gtod_notify,
+};
+
+static struct clocksource xen_clocksource __read_mostly = {
+	.name = "xen",
+	.rating = 400,
+	.read = xen_clocksource_get_cycles,
+	.mask = ~0,
+	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+/*
+   Xen clockevent implementation
+
+   Xen has two clockevent implementations:
+
+   The old timer_op one works with all released versions of Xen prior
+   to version 3.0.4.  This version of the hypervisor provides a
+   single-shot timer with nanosecond resolution.  However, sharing the
+   same event channel is a 100Hz tick which is delivered while the
+   vcpu is running.  We don't care about or use this tick, but it will
+   cause the core time code to think the timer fired too soon, and
+   will end up resetting it each time.  It could be filtered, but
+   doing so has complications when the ktime clocksource is not yet
+   the xen clocksource (ie, at boot time).
+
+   The new vcpu_op-based timer interface allows the tick timer period
+   to be changed or turned off.  The tick timer is not useful as a
+   periodic timer because events are only delivered to running vcpus.
+   The one-shot timer can report when a timeout is in the past, so
+   set_next_event is capable of returning -ETIME when appropriate.
+   This interface is used when available.
+*/
+
+
+/*
+  Get a hypervisor absolute time.  In theory we could maintain an
+  offset between the kernel's time and the hypervisor's time, and
+  apply that to a kernel's absolute timeout.  Unfortunately the
+  hypervisor and kernel times can drift even if the kernel is using
+  the Xen clocksource, because ntp can warp the kernel's clocksource.
+*/
+static s64 get_abs_timeout(unsigned long delta)
+{
+	return xen_clocksource_read() + delta;
+}
+
+static int xen_timerop_shutdown(struct clock_event_device *evt)
+{
+	/* cancel timeout */
+	HYPERVISOR_set_timer_op(0);
+
+	return 0;
+}
+
+static int xen_timerop_set_next_event(unsigned long delta,
+				      struct clock_event_device *evt)
+{
+	WARN_ON(!clockevent_state_oneshot(evt));
+
+	if (HYPERVISOR_set_timer_op(get_abs_timeout(delta)) < 0)
+		BUG();
+
+	/* We may have missed the deadline, but there's no real way of
+	   knowing for sure.  If the event was in the past, then we'll
+	   get an immediate interrupt. */
+
+	return 0;
+}
+
+static const struct clock_event_device xen_timerop_clockevent = {
+	.name			= "xen",
+	.features		= CLOCK_EVT_FEAT_ONESHOT,
+
+	.max_delta_ns		= 0xffffffff,
+	.max_delta_ticks	= 0xffffffff,
+	.min_delta_ns		= TIMER_SLOP,
+	.min_delta_ticks	= TIMER_SLOP,
+
+	.mult			= 1,
+	.shift			= 0,
+	.rating			= 500,
+
+	.set_state_shutdown	= xen_timerop_shutdown,
+	.set_next_event		= xen_timerop_set_next_event,
+};
+
+static int xen_vcpuop_shutdown(struct clock_event_device *evt)
+{
+	int cpu = smp_processor_id();
+
+	if (HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, xen_vcpu_nr(cpu),
+			       NULL) ||
+	    HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu),
+			       NULL))
+		BUG();
+
+	return 0;
+}
+
+static int xen_vcpuop_set_oneshot(struct clock_event_device *evt)
+{
+	int cpu = smp_processor_id();
+
+	if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu),
+			       NULL))
+		BUG();
+
+	return 0;
+}
+
+static int xen_vcpuop_set_next_event(unsigned long delta,
+				     struct clock_event_device *evt)
+{
+	int cpu = smp_processor_id();
+	struct vcpu_set_singleshot_timer single;
+	int ret;
+
+	WARN_ON(!clockevent_state_oneshot(evt));
+
+	single.timeout_abs_ns = get_abs_timeout(delta);
+	/* Get an event anyway, even if the timeout is already expired */
+	single.flags = 0;
+
+	ret = HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, xen_vcpu_nr(cpu),
+				 &single);
+	BUG_ON(ret != 0);
+
+	return ret;
+}
+
+static const struct clock_event_device xen_vcpuop_clockevent = {
+	.name = "xen",
+	.features = CLOCK_EVT_FEAT_ONESHOT,
+
+	.max_delta_ns = 0xffffffff,
+	.max_delta_ticks = 0xffffffff,
+	.min_delta_ns = TIMER_SLOP,
+	.min_delta_ticks = TIMER_SLOP,
+
+	.mult = 1,
+	.shift = 0,
+	.rating = 500,
+
+	.set_state_shutdown = xen_vcpuop_shutdown,
+	.set_state_oneshot = xen_vcpuop_set_oneshot,
+	.set_next_event = xen_vcpuop_set_next_event,
+};
+
+static const struct clock_event_device *xen_clockevent =
+	&xen_timerop_clockevent;
+
+struct xen_clock_event_device {
+	struct clock_event_device evt;
+	char name[16];
+};
+static DEFINE_PER_CPU(struct xen_clock_event_device, xen_clock_events) = { .evt.irq = -1 };
+
+static irqreturn_t xen_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = this_cpu_ptr(&xen_clock_events.evt);
+	irqreturn_t ret;
+
+	ret = IRQ_NONE;
+	if (evt->event_handler) {
+		evt->event_handler(evt);
+		ret = IRQ_HANDLED;
+	}
+
+	return ret;
+}
+
+void xen_teardown_timer(int cpu)
+{
+	struct clock_event_device *evt;
+	evt = &per_cpu(xen_clock_events, cpu).evt;
+
+	if (evt->irq >= 0) {
+		unbind_from_irqhandler(evt->irq, NULL);
+		evt->irq = -1;
+	}
+}
+
+void xen_setup_timer(int cpu)
+{
+	struct xen_clock_event_device *xevt = &per_cpu(xen_clock_events, cpu);
+	struct clock_event_device *evt = &xevt->evt;
+	int irq;
+
+	WARN(evt->irq >= 0, "IRQ%d for CPU%d is already allocated\n", evt->irq, cpu);
+	if (evt->irq >= 0)
+		xen_teardown_timer(cpu);
+
+	printk(KERN_INFO "installing Xen timer for CPU %d\n", cpu);
+
+	snprintf(xevt->name, sizeof(xevt->name), "timer%d", cpu);
+
+	irq = bind_virq_to_irqhandler(VIRQ_TIMER, cpu, xen_timer_interrupt,
+				      IRQF_PERCPU|IRQF_NOBALANCING|IRQF_TIMER|
+				      IRQF_FORCE_RESUME|IRQF_EARLY_RESUME,
+				      xevt->name, NULL);
+	(void)xen_set_irq_priority(irq, XEN_IRQ_PRIORITY_MAX);
+
+	memcpy(evt, xen_clockevent, sizeof(*evt));
+
+	evt->cpumask = cpumask_of(cpu);
+	evt->irq = irq;
+}
+
+
+void xen_setup_cpu_clockevents(void)
+{
+	clockevents_register_device(this_cpu_ptr(&xen_clock_events.evt));
+}
+
+void xen_timer_resume(void)
+{
+	int cpu;
+
+	if (xen_clockevent != &xen_vcpuop_clockevent)
+		return;
+
+	for_each_online_cpu(cpu) {
+		if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer,
+				       xen_vcpu_nr(cpu), NULL))
+			BUG();
+	}
+}
+
+static const struct pv_time_ops xen_time_ops __initconst = {
+	.sched_clock = xen_sched_clock,
+	.steal_clock = xen_steal_clock,
+};
+
+static struct pvclock_vsyscall_time_info *xen_clock __read_mostly;
+static u64 xen_clock_value_saved;
+
+void xen_save_time_memory_area(void)
+{
+	struct vcpu_register_time_memory_area t;
+	int ret;
+
+	xen_clock_value_saved = xen_clocksource_read() - xen_sched_clock_offset;
+
+	if (!xen_clock)
+		return;
+
+	t.addr.v = NULL;
+
+	ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
+	if (ret != 0)
+		pr_notice("Cannot save secondary vcpu_time_info (err %d)",
+			  ret);
+	else
+		clear_page(xen_clock);
+}
+
+void xen_restore_time_memory_area(void)
+{
+	struct vcpu_register_time_memory_area t;
+	int ret;
+
+	if (!xen_clock)
+		goto out;
+
+	t.addr.v = &xen_clock->pvti;
+
+	ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
+
+	/*
+	 * We don't disable VCLOCK_PVCLOCK entirely if it fails to register the
+	 * secondary time info with Xen or if we migrated to a host without the
+	 * necessary flags. On both of these cases what happens is either
+	 * process seeing a zeroed out pvti or seeing no PVCLOCK_TSC_STABLE_BIT
+	 * bit set. Userspace checks the latter and if 0, it discards the data
+	 * in pvti and fallbacks to a system call for a reliable timestamp.
+	 */
+	if (ret != 0)
+		pr_notice("Cannot restore secondary vcpu_time_info (err %d)",
+			  ret);
+
+out:
+	/* Need pvclock_resume() before using xen_clocksource_read(). */
+	pvclock_resume();
+	xen_sched_clock_offset = xen_clocksource_read() - xen_clock_value_saved;
+}
+
+static void xen_setup_vsyscall_time_info(void)
+{
+	struct vcpu_register_time_memory_area t;
+	struct pvclock_vsyscall_time_info *ti;
+	int ret;
+
+	ti = (struct pvclock_vsyscall_time_info *)get_zeroed_page(GFP_KERNEL);
+	if (!ti)
+		return;
+
+	t.addr.v = &ti->pvti;
+
+	ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
+	if (ret) {
+		pr_notice("xen: VCLOCK_PVCLOCK not supported (err %d)\n", ret);
+		free_page((unsigned long)ti);
+		return;
+	}
+
+	/*
+	 * If primary time info had this bit set, secondary should too since
+	 * it's the same data on both just different memory regions. But we
+	 * still check it in case hypervisor is buggy.
+	 */
+	if (!(ti->pvti.flags & PVCLOCK_TSC_STABLE_BIT)) {
+		t.addr.v = NULL;
+		ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area,
+					 0, &t);
+		if (!ret)
+			free_page((unsigned long)ti);
+
+		pr_notice("xen: VCLOCK_PVCLOCK not supported (tsc unstable)\n");
+		return;
+	}
+
+	xen_clock = ti;
+	pvclock_set_pvti_cpu0_va(xen_clock);
+
+	xen_clocksource.archdata.vclock_mode = VCLOCK_PVCLOCK;
+}
+
+static void __init xen_time_init(void)
+{
+	struct pvclock_vcpu_time_info *pvti;
+	int cpu = smp_processor_id();
+	struct timespec64 tp;
+
+	/* As Dom0 is never moved, no penalty on using TSC there */
+	if (xen_initial_domain())
+		xen_clocksource.rating = 275;
+
+	clocksource_register_hz(&xen_clocksource, NSEC_PER_SEC);
+
+	if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu),
+			       NULL) == 0) {
+		/* Successfully turned off 100Hz tick, so we have the
+		   vcpuop-based timer interface */
+		printk(KERN_DEBUG "Xen: using vcpuop timer interface\n");
+		xen_clockevent = &xen_vcpuop_clockevent;
+	}
+
+	/* Set initial system time with full resolution */
+	xen_read_wallclock(&tp);
+	do_settimeofday64(&tp);
+
+	setup_force_cpu_cap(X86_FEATURE_TSC);
+
+	/*
+	 * We check ahead on the primary time info if this
+	 * bit is supported hence speeding up Xen clocksource.
+	 */
+	pvti = &__this_cpu_read(xen_vcpu)->time;
+	if (pvti->flags & PVCLOCK_TSC_STABLE_BIT) {
+		pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
+		xen_setup_vsyscall_time_info();
+	}
+
+	xen_setup_runstate_info(cpu);
+	xen_setup_timer(cpu);
+	xen_setup_cpu_clockevents();
+
+	xen_time_setup_guest();
+
+	if (xen_initial_domain())
+		pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);
+}
+
+void __init xen_init_time_ops(void)
+{
+	xen_sched_clock_offset = xen_clocksource_read();
+	pv_time_ops = xen_time_ops;
+
+	x86_init.timers.timer_init = xen_time_init;
+	x86_init.timers.setup_percpu_clockev = x86_init_noop;
+	x86_cpuinit.setup_percpu_clockev = x86_init_noop;
+
+	x86_platform.calibrate_tsc = xen_tsc_khz;
+	x86_platform.get_wallclock = xen_get_wallclock;
+	/* Dom0 uses the native method to set the hardware RTC. */
+	if (!xen_initial_domain())
+		x86_platform.set_wallclock = xen_set_wallclock;
+}
+
+#ifdef CONFIG_XEN_PVHVM
+static void xen_hvm_setup_cpu_clockevents(void)
+{
+	int cpu = smp_processor_id();
+	xen_setup_runstate_info(cpu);
+	/*
+	 * xen_setup_timer(cpu) - snprintf is bad in atomic context. Hence
+	 * doing it xen_hvm_cpu_notify (which gets called by smp_init during
+	 * early bootup and also during CPU hotplug events).
+	 */
+	xen_setup_cpu_clockevents();
+}
+
+void __init xen_hvm_init_time_ops(void)
+{
+	static bool hvm_time_initialized;
+
+	if (hvm_time_initialized)
+		return;
+
+	/*
+	 * vector callback is needed otherwise we cannot receive interrupts
+	 * on cpu > 0 and at this point we don't know how many cpus are
+	 * available.
+	 */
+	if (!xen_have_vector_callback)
+		return;
+
+	if (!xen_feature(XENFEAT_hvm_safe_pvclock)) {
+		pr_info_once("Xen doesn't support pvclock on HVM, disable pv timer");
+		return;
+	}
+
+	/*
+	 * Only MAX_VIRT_CPUS 'vcpu_info' are embedded inside 'shared_info'.
+	 * The __this_cpu_read(xen_vcpu) is still NULL when Xen HVM guest
+	 * boots on vcpu >= MAX_VIRT_CPUS (e.g., kexec), To access
+	 * __this_cpu_read(xen_vcpu) via xen_clocksource_read() will panic.
+	 *
+	 * The xen_hvm_init_time_ops() should be called again later after
+	 * __this_cpu_read(xen_vcpu) is available.
+	 */
+	if (!__this_cpu_read(xen_vcpu)) {
+		pr_info("Delay xen_init_time_common() as kernel is running on vcpu=%d\n",
+			xen_vcpu_nr(0));
+		return;
+	}
+
+	xen_sched_clock_offset = xen_clocksource_read();
+	pv_time_ops = xen_time_ops;
+	x86_init.timers.setup_percpu_clockev = xen_time_init;
+	x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents;
+
+	x86_platform.calibrate_tsc = xen_tsc_khz;
+	x86_platform.get_wallclock = xen_get_wallclock;
+	x86_platform.set_wallclock = xen_set_wallclock;
+
+	hvm_time_initialized = true;
+}
+#endif