// SPDX-License-Identifier: GPL-2.0
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/*
|
* Xen time implementation.
|
*
|
* This is implemented in terms of a clocksource driver which uses
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* 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
|
*/
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#include <linux/kernel.h>
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#include <linux/interrupt.h>
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#include <linux/clocksource.h>
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#include <linux/clockchips.h>
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#include <linux/gfp.h>
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#include <linux/slab.h>
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#include <linux/pvclock_gtod.h>
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#include <linux/timekeeper_internal.h>
|
|
#include <asm/pvclock.h>
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#include <asm/xen/hypervisor.h>
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#include <asm/xen/hypercall.h>
|
|
#include <xen/events.h>
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#include <xen/features.h>
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#include <xen/interface/xen.h>
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#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);
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}
|
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static u64 xen_clocksource_read(void)
|
{
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struct pvclock_vcpu_time_info *src;
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u64 ret;
|
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preempt_disable_notrace();
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src = &__this_cpu_read(xen_vcpu)->time;
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ret = pvclock_clocksource_read(src);
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preempt_enable_notrace();
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return ret;
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}
|
|
static u64 xen_clocksource_get_cycles(struct clocksource *cs)
|
{
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return xen_clocksource_read();
|
}
|
|
static u64 xen_sched_clock(void)
|
{
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return xen_clocksource_read() - xen_sched_clock_offset;
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}
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static void xen_read_wallclock(struct timespec64 *ts)
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{
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struct shared_info *s = HYPERVISOR_shared_info;
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struct pvclock_wall_clock *wall_clock = &(s->wc);
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struct pvclock_vcpu_time_info *vcpu_time;
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vcpu_time = &get_cpu_var(xen_vcpu)->time;
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pvclock_read_wallclock(wall_clock, vcpu_time, ts);
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put_cpu_var(xen_vcpu);
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}
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static void xen_get_wallclock(struct timespec64 *now)
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{
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xen_read_wallclock(now);
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}
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static int xen_set_wallclock(const struct timespec64 *now)
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{
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return -ENODEV;
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}
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static int xen_pvclock_gtod_notify(struct notifier_block *nb,
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unsigned long was_set, void *priv)
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{
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/* Protected by the calling core code serialization */
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static struct timespec64 next_sync;
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struct xen_platform_op op;
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struct timespec64 now;
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struct timekeeper *tk = priv;
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static bool settime64_supported = true;
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int ret;
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now.tv_sec = tk->xtime_sec;
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now.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
|
|
/*
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* We only take the expensive HV call when the clock was set
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* or when the 11 minutes RTC synchronization time elapsed.
|
*/
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if (!was_set && timespec64_compare(&now, &next_sync) < 0)
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return NOTIFY_OK;
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|
again:
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if (settime64_supported) {
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op.cmd = XENPF_settime64;
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op.u.settime64.mbz = 0;
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op.u.settime64.secs = now.tv_sec;
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op.u.settime64.nsecs = now.tv_nsec;
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op.u.settime64.system_time = xen_clocksource_read();
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} else {
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op.cmd = XENPF_settime32;
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op.u.settime32.secs = now.tv_sec;
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op.u.settime32.nsecs = now.tv_nsec;
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op.u.settime32.system_time = xen_clocksource_read();
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}
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ret = HYPERVISOR_platform_op(&op);
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if (ret == -ENOSYS && settime64_supported) {
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settime64_supported = false;
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goto again;
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}
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if (ret < 0)
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return NOTIFY_BAD;
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/*
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* Move the next drift compensation time 11 minutes
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* ahead. That's emulating the sync_cmos_clock() update for
|
* the hardware RTC.
|
*/
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next_sync = now;
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next_sync.tv_sec += 11 * 60;
|
|
return NOTIFY_OK;
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}
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static struct notifier_block xen_pvclock_gtod_notifier = {
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.notifier_call = xen_pvclock_gtod_notify,
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};
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static struct clocksource xen_clocksource __read_mostly = {
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.name = "xen",
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.rating = 400,
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.read = xen_clocksource_get_cycles,
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.mask = ~0,
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.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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};
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|
/*
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Xen clockevent implementation
|
|
Xen has two clockevent implementations:
|
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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
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will end up resetting it each time. It could be filtered, but
|
doing so has complications when the ktime clocksource is not yet
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the xen clocksource (ie, at boot time).
|
|
The new vcpu_op-based timer interface allows the tick timer period
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to be changed or turned off. The tick timer is not useful as a
|
periodic timer because events are only delivered to running vcpus.
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The one-shot timer can report when a timeout is in the past, so
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set_next_event is capable of returning -ETIME when appropriate.
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This interface is used when available.
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*/
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|
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/*
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Get a hypervisor absolute time. In theory we could maintain an
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offset between the kernel's time and the hypervisor's time, and
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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.
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*/
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static s64 get_abs_timeout(unsigned long delta)
|
{
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return xen_clocksource_read() + delta;
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}
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static int xen_timerop_shutdown(struct clock_event_device *evt)
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{
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/* cancel timeout */
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HYPERVISOR_set_timer_op(0);
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return 0;
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}
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static int xen_timerop_set_next_event(unsigned long delta,
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struct clock_event_device *evt)
|
{
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WARN_ON(!clockevent_state_oneshot(evt));
|
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if (HYPERVISOR_set_timer_op(get_abs_timeout(delta)) < 0)
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BUG();
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/* 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
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get an immediate interrupt. */
|
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return 0;
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}
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static const struct clock_event_device xen_timerop_clockevent = {
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.name = "xen",
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.features = CLOCK_EVT_FEAT_ONESHOT,
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.max_delta_ns = 0xffffffff,
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.max_delta_ticks = 0xffffffff,
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.min_delta_ns = TIMER_SLOP,
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.min_delta_ticks = TIMER_SLOP,
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.mult = 1,
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.shift = 0,
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.rating = 500,
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.set_state_shutdown = xen_timerop_shutdown,
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.set_next_event = xen_timerop_set_next_event,
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};
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static int xen_vcpuop_shutdown(struct clock_event_device *evt)
|
{
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int cpu = smp_processor_id();
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if (HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, xen_vcpu_nr(cpu),
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NULL) ||
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HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu),
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NULL))
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BUG();
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return 0;
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}
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static int xen_vcpuop_set_oneshot(struct clock_event_device *evt)
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{
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int cpu = smp_processor_id();
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if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu),
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NULL))
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BUG();
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return 0;
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}
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static int xen_vcpuop_set_next_event(unsigned long delta,
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struct clock_event_device *evt)
|
{
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int cpu = smp_processor_id();
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struct vcpu_set_singleshot_timer single;
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int ret;
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WARN_ON(!clockevent_state_oneshot(evt));
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single.timeout_abs_ns = get_abs_timeout(delta);
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/* Get an event anyway, even if the timeout is already expired */
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single.flags = 0;
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ret = HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, xen_vcpu_nr(cpu),
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&single);
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BUG_ON(ret != 0);
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return ret;
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}
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static const struct clock_event_device xen_vcpuop_clockevent = {
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.name = "xen",
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.features = CLOCK_EVT_FEAT_ONESHOT,
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.max_delta_ns = 0xffffffff,
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.max_delta_ticks = 0xffffffff,
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.min_delta_ns = TIMER_SLOP,
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.min_delta_ticks = TIMER_SLOP,
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.mult = 1,
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.shift = 0,
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.rating = 500,
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.set_state_shutdown = xen_vcpuop_shutdown,
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.set_state_oneshot = xen_vcpuop_set_oneshot,
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.set_next_event = xen_vcpuop_set_next_event,
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};
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static const struct clock_event_device *xen_clockevent =
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&xen_timerop_clockevent;
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struct xen_clock_event_device {
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struct clock_event_device evt;
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char name[16];
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};
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static DEFINE_PER_CPU(struct xen_clock_event_device, xen_clock_events) = { .evt.irq = -1 };
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static irqreturn_t xen_timer_interrupt(int irq, void *dev_id)
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{
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struct clock_event_device *evt = this_cpu_ptr(&xen_clock_events.evt);
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irqreturn_t ret;
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ret = IRQ_NONE;
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if (evt->event_handler) {
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evt->event_handler(evt);
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ret = IRQ_HANDLED;
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}
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|
return ret;
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}
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void xen_teardown_timer(int cpu)
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{
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struct clock_event_device *evt;
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evt = &per_cpu(xen_clock_events, cpu).evt;
|
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if (evt->irq >= 0) {
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unbind_from_irqhandler(evt->irq, NULL);
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evt->irq = -1;
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}
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}
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void xen_setup_timer(int cpu)
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{
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struct xen_clock_event_device *xevt = &per_cpu(xen_clock_events, cpu);
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struct clock_event_device *evt = &xevt->evt;
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int irq;
|
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WARN(evt->irq >= 0, "IRQ%d for CPU%d is already allocated\n", evt->irq, cpu);
|
if (evt->irq >= 0)
|
xen_teardown_timer(cpu);
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|
printk(KERN_INFO "installing Xen timer for CPU %d\n", cpu);
|
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snprintf(xevt->name, sizeof(xevt->name), "timer%d", cpu);
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irq = bind_virq_to_irqhandler(VIRQ_TIMER, cpu, xen_timer_interrupt,
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IRQF_PERCPU|IRQF_NOBALANCING|IRQF_TIMER|
|
IRQF_FORCE_RESUME|IRQF_EARLY_RESUME,
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xevt->name, NULL);
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(void)xen_set_irq_priority(irq, XEN_IRQ_PRIORITY_MAX);
|
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memcpy(evt, xen_clockevent, sizeof(*evt));
|
|
evt->cpumask = cpumask_of(cpu);
|
evt->irq = irq;
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}
|
|
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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();
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}
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}
|
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static const struct pv_time_ops xen_time_ops __initconst = {
|
.sched_clock = xen_sched_clock,
|
.steal_clock = xen_steal_clock,
|
};
|
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static struct pvclock_vsyscall_time_info *xen_clock __read_mostly;
|
static u64 xen_clock_value_saved;
|
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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;
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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)
|
{
|
/*
|
* 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
|
