Merge tag 'hyperv-next-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/hyper...

[linux-2.6-microblaze.git] / drivers / hv / hv_util.c

diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index f2845e9..05566ec 100644 (file)
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -282,26 +282,52 @@ static struct {
        spinlock_t                      lock;
 } host_ts;
 
-static struct timespec64 hv_get_adj_host_time(void)
+static inline u64 reftime_to_ns(u64 reftime)
 {
-       struct timespec64 ts;
-       u64 newtime, reftime;
+       return (reftime - WLTIMEDELTA) * 100;
+}
+
+/*
+ * Hard coded threshold for host timesync delay: 600 seconds
+ */
+static const u64 HOST_TIMESYNC_DELAY_THRESH = 600 * (u64)NSEC_PER_SEC;
+
+static int hv_get_adj_host_time(struct timespec64 *ts)
+{
+       u64 newtime, reftime, timediff_adj;
        unsigned long flags;
+       int ret = 0;
 
        spin_lock_irqsave(&host_ts.lock, flags);
        reftime = hv_read_reference_counter();
-       newtime = host_ts.host_time + (reftime - host_ts.ref_time);
-       ts = ns_to_timespec64((newtime - WLTIMEDELTA) * 100);
+
+       /*
+        * We need to let the caller know that last update from host
+        * is older than the max allowable threshold. clock_gettime()
+        * and PTP ioctl do not have a documented error that we could
+        * return for this specific case. Use ESTALE to report this.
+        */
+       timediff_adj = reftime - host_ts.ref_time;
+       if (timediff_adj * 100 > HOST_TIMESYNC_DELAY_THRESH) {
+               pr_warn_once("TIMESYNC IC: Stale time stamp, %llu nsecs old\n",
+                            (timediff_adj * 100));
+               ret = -ESTALE;
+       }
+
+       newtime = host_ts.host_time + timediff_adj;
+       *ts = ns_to_timespec64(reftime_to_ns(newtime));
        spin_unlock_irqrestore(&host_ts.lock, flags);
 
-       return ts;
+       return ret;
 }
 
 static void hv_set_host_time(struct work_struct *work)
 {
-       struct timespec64 ts = hv_get_adj_host_time();
 
-       do_settimeofday64(&ts);
+       struct timespec64 ts;
+
+       if (!hv_get_adj_host_time(&ts))
+               do_settimeofday64(&ts);
 }
 
 /*
@@ -361,10 +387,23 @@ static void timesync_onchannelcallback(void *context)
        struct ictimesync_ref_data *refdata;
        u8 *time_txf_buf = util_timesynch.recv_buffer;
 
-       vmbus_recvpacket(channel, time_txf_buf,
-                        HV_HYP_PAGE_SIZE, &recvlen, &requestid);
+       /*
+        * Drain the ring buffer and use the last packet to update
+        * host_ts
+        */
+       while (1) {
+               int ret = vmbus_recvpacket(channel, time_txf_buf,
+                                          HV_HYP_PAGE_SIZE, &recvlen,
+                                          &requestid);
+               if (ret) {
+                       pr_warn_once("TimeSync IC pkt recv failed (Err: %d)\n",
+                                    ret);
+                       break;
+               }
+
+               if (!recvlen)
+                       break;
 
-       if (recvlen > 0) {
                icmsghdrp = (struct icmsg_hdr *)&time_txf_buf[
                                sizeof(struct vmbuspipe_hdr)];
 
@@ -625,9 +664,7 @@ static int hv_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
 
 static int hv_ptp_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
 {
-       *ts = hv_get_adj_host_time();
-
-       return 0;
+       return hv_get_adj_host_time(ts);
 }
 
 static struct ptp_clock_info ptp_hyperv_info = {