Index: sys/arm64/arm64/pmap.c
===================================================================
--- sys/arm64/arm64/pmap.c
+++ sys/arm64/arm64/pmap.c
@@ -359,6 +359,8 @@
 					    ((u_long)(epoch) << 32)))
 #define	COOKIE_TO_ASID(cookie)		((int)(cookie))
 #define	COOKIE_TO_EPOCH(cookie)		((int)((u_long)(cookie) >> 32))
+#define	COOKIE_TO_EPOCH_ATOMIC(cookie)	((int)(atomic_load_long( \
+					    &(cookie)) >> 32))
 
 static int superpages_enabled = 1;
 SYSCTL_INT(_vm_pmap, OID_AUTO, superpages_enabled,
@@ -1175,6 +1177,32 @@
 SYSCTL_ULONG(_vm_pmap_l2, OID_AUTO, promotions, CTLFLAG_RD,
     &pmap_l2_promotions, 0, "2MB page promotions");
 
+static bool
+pmap_is_current_epoch(pmap_t pmap)
+{
+	struct asid_set *set;
+	int asid_epoch, epoch;
+
+	/* The kernel pmap is always current, and may not be locked */
+	if (pmap == kernel_pmap)
+		return (true);
+
+	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
+	set = pmap->pm_asid_set;
+
+	/* Check if the epoch is marked as invalid */
+	epoch = COOKIE_TO_EPOCH_ATOMIC(pmap->pm_cookie);
+	if (epoch == INT_MAX)
+		return (false);
+
+	/* Assume current while pmap_reset_asid_set is being called */
+	asid_epoch = atomic_load_int(&set->asid_epoch);
+	if (asid_epoch == -1)
+		return (true);
+
+	return (epoch == asid_epoch);
+}
+
 /*
  * Invalidate a single TLB entry.
  */
@@ -1228,6 +1256,15 @@
 
 	PMAP_ASSERT_STAGE1(pmap);
 
+	/*
+	 * Invalidating all entries can be expensive. Only do so if the pmap
+	 * is on the current epoch. If not the pmap will have not been
+	 * activated since the last time the entire tlb was invalidated so
+	 * won't have been used.
+	 */
+	if (!pmap_is_current_epoch(pmap))
+		return;
+
 	dsb(ishst);
 	if (pmap == kernel_pmap) {
 		__asm __volatile("tlbi vmalle1is");
@@ -6451,7 +6488,7 @@
 	epoch = set->asid_epoch + 1;
 	if (epoch == INT_MAX)
 		epoch = 0;
-	set->asid_epoch = epoch;
+	atomic_store_int(&set->asid_epoch, -1);
 	dsb(ishst);
 	if (stage == PM_STAGE1) {
 		__asm __volatile("tlbi vmalle1is");
@@ -6481,8 +6518,10 @@
 		if (asid == -1)
 			continue;
 		bit_set(set->asid_set, asid);
-		curpmap->pm_cookie = COOKIE_FROM(asid, epoch);
+		atomic_store_long(&curpmap->pm_cookie,
+		    COOKIE_FROM(asid, epoch));
 	}
+	atomic_store_rel_int(&set->asid_epoch, epoch);
 }
 
 /*