[Xen-devel] [PATCH v7 05/19] xen: rework xen timer so it can be used early in boot process

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

This should not introduce any functional change, and makes the
functions suitable to be called before we have actually mapped the
vcpu_info struct on a per-cpu basis.
---
 sys/dev/xen/timer/timer.c |   29 ++++++++++++++++++++---------
 1 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/sys/dev/xen/timer/timer.c b/sys/dev/xen/timer/timer.c
index 354085b..b2f6bcd 100644
--- a/sys/dev/xen/timer/timer.c
+++ b/sys/dev/xen/timer/timer.c
@@ -230,22 +230,22 @@ xen_fetch_vcpu_tinfo(struct vcpu_time_info *dst, struct 
vcpu_time_info *src)
 /**
  * \brief Get the current time, in nanoseconds, since the hypervisor booted.
  *
+ * \param vcpu         vcpu_info structure to fetch the time from.
+ *
  * \note This function returns the current CPU's idea of this value, unless
  *       it happens to be less than another CPU's previously determined value.
  */
 static uint64_t
-xen_fetch_vcpu_time(void)
+xen_fetch_vcpu_time(struct vcpu_info *vcpu)
 {
        struct vcpu_time_info dst;
        struct vcpu_time_info *src;
        uint32_t pre_version;
        uint64_t now;
        volatile uint64_t last;
-       struct vcpu_info *vcpu = DPCPU_GET(vcpu_info);
 
        src = &vcpu->time;
 
-       critical_enter();
        do {
                pre_version = xen_fetch_vcpu_tinfo(&dst, src);
                barrier();
@@ -266,16 +266,19 @@ xen_fetch_vcpu_time(void)
                }
        } while (!atomic_cmpset_64(&xen_timer_last_time, last, now));
 
-       critical_exit();
-
        return (now);
 }
 
 static uint32_t
 xentimer_get_timecount(struct timecounter *tc)
 {
+       uint32_t xen_time;
 
-       return ((uint32_t)xen_fetch_vcpu_time() & UINT_MAX);
+       critical_enter();
+       xen_time = (uint32_t)xen_fetch_vcpu_time(DPCPU_GET(vcpu_info)) & 
UINT_MAX;
+       critical_exit();
+
+       return (xen_time);
 }
 
 /**
@@ -305,7 +308,12 @@ xen_fetch_wallclock(struct timespec *ts)
 static void
 xen_fetch_uptime(struct timespec *ts)
 {
-       uint64_t uptime = xen_fetch_vcpu_time();
+       uint64_t uptime;
+
+       critical_enter();
+       uptime = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
+       critical_exit();
+
        ts->tv_sec = uptime / NSEC_IN_SEC;
        ts->tv_nsec = uptime % NSEC_IN_SEC;
 }
@@ -354,7 +362,7 @@ xentimer_intr(void *arg)
        struct xentimer_softc *sc = (struct xentimer_softc *)arg;
        struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu);
 
-       pcpu->last_processed = xen_fetch_vcpu_time();
+       pcpu->last_processed = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
        if (pcpu->timer != 0 && sc->et.et_active)
                sc->et.et_event_cb(&sc->et, sc->et.et_arg);
 
@@ -415,7 +423,10 @@ xentimer_et_start(struct eventtimer *et,
        do {
                if (++i == 60)
                        panic("can't schedule timer");
-               next_time = xen_fetch_vcpu_time() + first_in_ns;
+               critical_enter();
+               next_time = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info)) +
+                           first_in_ns;
+               critical_exit();
                error = xentimer_vcpu_start_timer(cpu, next_time);
        } while (error == -ETIME);
 
-- 
1.7.7.5 (Apple Git-26)


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