v4.19.13 snapshot.
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
new file mode 100644
index 0000000..c84f1e0
--- /dev/null
+++ b/arch/x86/xen/time.c
@@ -0,0 +1,566 @@
+// 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;
+
+ pvclock_resume();
+
+ 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;
+
+void xen_save_time_memory_area(void)
+{
+ struct vcpu_register_time_memory_area t;
+ int ret;
+
+ 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)
+ return;
+
+ 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);
+}
+
+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)
+{
+ /*
+ * 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("Xen doesn't support pvclock on HVM, disable pv timer");
+ 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;
+}
+#endif