Have our dom0 periodically set Xen's time-of-day clock (much as Linux does).
That time is used by ~all domUs when they boot (or resume), and Linux by default will pin the local clock to it; so, it's useful to correct its drift as best we can. A sysctl (machdep.xen_timepush_ticks) has been added to allow changing the interval or disabling this feature.
This commit is contained in:
jld
parent
0f4e4cae54
commit
78e3490d47
@ -1,4 +1,4 @@
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/* $NetBSD: clock.c,v 1.22 2006/04/28 02:30:42 jld Exp $ */
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/* $NetBSD: clock.c,v 1.23 2006/05/05 19:38:38 jld Exp $ */
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/*
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*
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@ -34,13 +34,14 @@
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#include "opt_xen.h"
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.22 2006/04/28 02:30:42 jld Exp $");
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__KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.23 2006/05/05 19:38:38 jld Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/time.h>
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#include <sys/kernel.h>
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#include <sys/device.h>
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#include <sys/sysctl.h>
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#include <machine/xen.h>
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#include <machine/hypervisor.h>
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@ -69,6 +70,12 @@ static int timeset;
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static uint64_t processed_system_time;
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#ifdef DOM0OPS
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/* If we're dom0, send our time to Xen every minute or so. */
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int xen_timepush_ticks = 0;
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static struct callout xen_timepush_co = CALLOUT_INITIALIZER;
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#endif
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#define NS_PER_TICK (1000000000ULL/hz)
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/*
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@ -171,15 +178,15 @@ fstime:
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printf("WARNING: CHECK AND RESET THE DATE!\n");
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}
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void
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resettodr()
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static void
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resettodr_i(void)
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{
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#ifdef DOM0OPS
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dom0_op_t op;
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int s;
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#endif
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#ifdef DEBUG_CLOCK
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struct clock_ymdhms dt;
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struct timeval sent_delta;
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#endif
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/*
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@ -190,10 +197,19 @@ resettodr()
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return;
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#ifdef DEBUG_CLOCK
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clock_secs_to_ymdhms(time.tv_sec - rtc_offset * 60, &dt);
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printf("setclock: %d/%d/%d %02d:%02d:%02d\n", dt.dt_year,
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dt.dt_mon, dt.dt_day, dt.dt_hour, dt.dt_min, dt.dt_sec);
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{
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char pm;
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if (timercmp(&time, &shadow_tv, >)) {
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timersub(&time, &shadow_tv, &sent_delta);
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pm = '+';
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} else {
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timersub(&shadow_tv, &time, &sent_delta);
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pm = '-';
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}
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printf("resettodr: stepping Xen clock by %c%ld.%06ld\n",
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pm, sent_delta.tv_sec, sent_delta.tv_usec);
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}
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#endif
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#ifdef DOM0OPS
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if (xen_start_info.flags & SIF_PRIVILEGED) {
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@ -214,6 +230,22 @@ resettodr()
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#endif
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}
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/*
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* When the clock is administratively set, in addition to resetting
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* Xen's clock if possible, we should also allow xen_microtime to
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* step backwards without complaint.
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*/
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void
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resettodr()
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{
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CPU_INFO_ITERATOR cii;
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struct cpu_info *ci;
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resettodr_i();
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for (CPU_INFO_FOREACH(cii, ci))
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timerclear(&ci->ci_cc.cc_time);
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}
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void
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startrtclock()
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{
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@ -301,11 +333,12 @@ xen_microtime(struct timeval *tv)
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tv->tv_sec++;
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tv->tv_usec -= 1000000;
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}
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/* Avoid backsteps, e.g. at the beginning of a negative adjustment. */
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/* Avoid small backsteps, e.g. at the beginning of a negative adjustment. */
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if (timerisset(&ci->ci_cc.cc_time) &&
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timercmp(tv, &ci->ci_cc.cc_time, <)) {
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struct timeval backstep; /* XXX hook resettodr() instead of doing this. */
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struct timeval backstep;
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/* XXXjld: not sure if this check can be safely removed now */
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timersub(&ci->ci_cc.cc_time, tv, &backstep);
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if (backstep.tv_sec == 0) { /* if it was < 1sec */
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*tv = ci->ci_cc.cc_time;
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@ -323,11 +356,52 @@ xen_microtime(struct timeval *tv)
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splx(s);
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}
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#ifdef DOM0OPS
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/* ARGSUSED */
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static void
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xen_timepush(void *arg)
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{
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struct callout *co = arg;
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resettodr_i();
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if (xen_timepush_ticks > 0)
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callout_schedule(co, xen_timepush_ticks);
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}
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/* ARGSUSED */
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static int
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sysctl_xen_timepush(SYSCTLFN_ARGS)
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{
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int error, new_ticks;
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struct sysctlnode node;
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new_ticks = xen_timepush_ticks;
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node = *rnode;
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node.sysctl_data = &new_ticks;
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error = sysctl_lookup(SYSCTLFN_CALL(&node));
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if (error || newp == NULL)
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return error;
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if (new_ticks < 0)
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return EINVAL;
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if (new_ticks != xen_timepush_ticks) {
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xen_timepush_ticks = new_ticks;
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if (new_ticks > 0)
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callout_schedule(&xen_timepush_co, new_ticks);
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else
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callout_stop(&xen_timepush_co);
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}
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return 0;
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}
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#endif
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void
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xen_initclocks()
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{
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int evtch = bind_virq_to_evtch(VIRQ_TIMER);
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int evtch;
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evtch = bind_virq_to_evtch(VIRQ_TIMER);
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aprint_verbose("Xen clock: using event channel %d\n", evtch);
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get_time_values_from_xen();
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@ -336,6 +410,19 @@ xen_initclocks()
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event_set_handler(evtch, (int (*)(void *))xen_timer_handler,
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NULL, IPL_CLOCK, "clock");
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hypervisor_enable_event(evtch);
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#ifdef DOM0OPS
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xen_timepush_ticks = 53 * hz + 3; /* avoid exact # of min/sec */
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if (xen_start_info.flags & SIF_PRIVILEGED) {
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sysctl_createv(NULL, 0, NULL, NULL, CTLFLAG_READWRITE,
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CTLTYPE_INT, "xen_timepush_ticks", SYSCTL_DESCR("How often"
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" to update the hypervisor's time-of-day; 0 to disable"),
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sysctl_xen_timepush, 0, &xen_timepush_ticks, 0,
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CTL_MACHDEP, CTL_CREATE, CTL_EOL);
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callout_reset(&xen_timepush_co, xen_timepush_ticks,
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&xen_timepush, &xen_timepush_co);
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}
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#endif
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}
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static int
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