diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index a4effc3c49..d62c715ca3 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1027,7 +1027,7 @@ long arch_do_domctl(
         struct vcpu *v;
 
         ret = -EBUSY;
-        if ( !d->is_paused_by_controller )
+        if ( d->controller_pause_count > 0 )
             break;
         ret = -EINVAL;
         if ( domctl->u.gdbsx_pauseunp_vcpu.vcpu >= MAX_VIRT_CPUS ||
@@ -1043,7 +1043,7 @@ long arch_do_domctl(
         struct vcpu *v;
 
         ret = -EBUSY;
-        if ( !d->is_paused_by_controller )
+        if ( d->controller_pause_count > 0 )
             break;
         ret = -EINVAL;
         if ( domctl->u.gdbsx_pauseunp_vcpu.vcpu >= MAX_VIRT_CPUS ||
@@ -1061,7 +1061,7 @@ long arch_do_domctl(
         struct vcpu *v;
 
         domctl->u.gdbsx_domstatus.vcpu_id = -1;
-        domctl->u.gdbsx_domstatus.paused = d->is_paused_by_controller;
+        domctl->u.gdbsx_domstatus.paused = d->controller_pause_count > 0;
         if ( domctl->u.gdbsx_domstatus.paused )
         {
             for_each_vcpu ( d, v )
diff --git a/xen/common/domain.c b/xen/common/domain.c
index c3a576e2e4..cd64aea7ac 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -317,7 +317,7 @@ struct domain *domain_create(
         if ( (err = xsm_domain_create(XSM_HOOK, d, ssidref)) != 0 )
             goto fail;
 
-        d->is_paused_by_controller = 1;
+        d->controller_pause_count = 1;
         atomic_inc(&d->pause_count);
 
         if ( !is_hardware_domain(d) )
@@ -755,18 +755,13 @@ void vcpu_end_shutdown_deferral(struct vcpu *v)
 #ifdef HAS_GDBSX
 void domain_pause_for_debugger(void)
 {
-    struct domain *d = current->domain;
-    struct vcpu *v;
+    struct vcpu *curr = current;
+    struct domain *d = curr->domain;
 
-    atomic_inc(&d->pause_count);
-    if ( test_and_set_bool(d->is_paused_by_controller) )
-        domain_unpause(d); /* race-free atomic_dec(&d->pause_count) */
-
-    for_each_vcpu ( d, v )
-        vcpu_sleep_nosync(v);
+    domain_pause_by_systemcontroller_nosync(d);
 
     /* if gdbsx active, we just need to pause the domain */
-    if (current->arch.gdbsx_vcpu_event == 0)
+    if ( curr->arch.gdbsx_vcpu_event == 0 )
         send_global_virq(VIRQ_DEBUGGER);
 }
 #endif
@@ -914,17 +909,49 @@ void domain_unpause(struct domain *d)
             vcpu_wake(v);
 }
 
-void domain_pause_by_systemcontroller(struct domain *d)
+int __domain_pause_by_systemcontroller(struct domain *d,
+                                       void (*pause_fn)(struct domain *d))
 {
-    domain_pause(d);
-    if ( test_and_set_bool(d->is_paused_by_controller) )
-        domain_unpause(d);
+    int old, new, prev = d->controller_pause_count;
+
+    do
+    {
+        old = prev;
+        new = old + 1;
+
+        /*
+         * Limit the toolstack pause count to an arbitrary 255 to prevent the
+         * toolstack overflowing d->pause_count with many repeated hypercalls.
+         */
+        if ( new > 255 )
+            return -EUSERS;
+
+        prev = cmpxchg(&d->controller_pause_count, old, new);
+    } while ( prev != old );
+
+    pause_fn(d);
+
+    return 0;
 }
 
-void domain_unpause_by_systemcontroller(struct domain *d)
+int domain_unpause_by_systemcontroller(struct domain *d)
 {
-    if ( test_and_clear_bool(d->is_paused_by_controller) )
-        domain_unpause(d);
+    int old, new, prev = d->controller_pause_count;
+
+    do
+    {
+        old = prev;
+        new = old - 1;
+
+        if ( new < 0 )
+            return -EINVAL;
+
+        prev = cmpxchg(&d->controller_pause_count, old, new);
+    } while ( prev != old );
+
+    domain_unpause(d);
+
+    return 0;
 }
 
 int vcpu_reset(struct vcpu *v)
diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index 000993f70e..c326aba255 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -181,7 +181,7 @@ void getdomaininfo(struct domain *d, struct xen_domctl_getdomaininfo *info)
     info->flags = (info->nr_online_vcpus ? flags : 0) |
         ((d->is_dying == DOMDYING_dead) ? XEN_DOMINF_dying    : 0) |
         (d->is_shut_down                ? XEN_DOMINF_shutdown : 0) |
-        (d->is_paused_by_controller     ? XEN_DOMINF_paused   : 0) |
+        (d->controller_pause_count > 0  ? XEN_DOMINF_paused   : 0) |
         (d->debugger_attached           ? XEN_DOMINF_debugged : 0) |
         d->shutdown_code << XEN_DOMINF_shutdownshift;
 
@@ -394,22 +394,14 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
     break;
 
     case XEN_DOMCTL_pausedomain:
-    {
         ret = -EINVAL;
         if ( d != current->domain )
-        {
-            domain_pause_by_systemcontroller(d);
-            ret = 0;
-        }
-    }
-    break;
+            ret = domain_pause_by_systemcontroller(d);
+        break;
 
     case XEN_DOMCTL_unpausedomain:
-    {
-        domain_unpause_by_systemcontroller(d);
-        ret = 0;
-    }
-    break;
+        ret = domain_unpause_by_systemcontroller(d);
+        break;
 
     case XEN_DOMCTL_resumedomain:
     {
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index f920e1a3be..d5bc461e06 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -366,7 +366,7 @@ struct domain
     /* Is this guest dying (i.e., a zombie)? */
     enum { DOMDYING_alive, DOMDYING_dying, DOMDYING_dead } is_dying;
     /* Domain is paused by controller software? */
-    bool_t           is_paused_by_controller;
+    int              controller_pause_count;
     /* Domain's VCPUs are pinned 1:1 to physical CPUs? */
     bool_t           is_pinned;
 
@@ -769,8 +769,17 @@ void domain_pause(struct domain *d);
 void domain_pause_nosync(struct domain *d);
 void vcpu_unpause(struct vcpu *v);
 void domain_unpause(struct domain *d);
-void domain_pause_by_systemcontroller(struct domain *d);
-void domain_unpause_by_systemcontroller(struct domain *d);
+int domain_unpause_by_systemcontroller(struct domain *d);
+int __domain_pause_by_systemcontroller(struct domain *d,
+                                       void (*pause_fn)(struct domain *d));
+static inline int domain_pause_by_systemcontroller(struct domain *d)
+{
+    return __domain_pause_by_systemcontroller(d, domain_pause);
+}
+static inline int domain_pause_by_systemcontroller_nosync(struct domain *d)
+{
+    return __domain_pause_by_systemcontroller(d, domain_pause_nosync);
+}
 void cpu_init(void);
 
 struct scheduler;