commit 0d2beb3d4125d65c415860d66974db9a5532ac84
Author: Dario Faggioli <dfaggioli@xxxxxxxx>
Date:   Wed Sep 26 11:47:06 2018 +0200

    xen: RCU: bootparam to force quiescence at every call.
    
    Signed-off-by: Dario Faggioli <dfaggioli@xxxxxxxx>

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 0f4b1f2a5d..536eb17017 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -110,7 +110,10 @@ static enum {
 static int __init parse_vwfi(const char *s)
 {
 	if ( !strcmp(s, "native") )
+	{
+		rcu_always_quiesc = true;
 		vwfi = NATIVE;
+	}
 	else
 		vwfi = TRAP;
 
diff --git a/xen/common/rcupdate.c b/xen/common/rcupdate.c
index 3517790913..219dd2884f 100644
--- a/xen/common/rcupdate.c
+++ b/xen/common/rcupdate.c
@@ -140,6 +140,9 @@ static int qhimark = 10000;
 static int qlowmark = 100;
 static int rsinterval = 1000;
 
+bool rcu_always_quiesc = false;
+boolean_param("rcu_force_quiesc", rcu_always_quiesc);
+
 struct rcu_barrier_data {
     struct rcu_head head;
     atomic_t *cpu_count;
@@ -562,6 +565,13 @@ static void rcu_init_percpu_data(int cpu, struct rcu_ctrlblk *rcp,
     rdp->quiescbatch = rcp->completed;
     rdp->qs_pending = 0;
     rdp->cpu = cpu;
+    if ( rcu_always_quiesc )
+    {
+        blimit = INT_MAX;
+        qhimark = 0;
+        qlowmark = 0;
+        //rsinterval = 0;
+    }
     rdp->blimit = blimit;
     init_timer(&rdp->idle_timer, rcu_idle_timer_handler, rdp, cpu);
 }
diff --git a/xen/include/xen/rcupdate.h b/xen/include/xen/rcupdate.h
index 3402eb5caf..274a01acf6 100644
--- a/xen/include/xen/rcupdate.h
+++ b/xen/include/xen/rcupdate.h
@@ -56,6 +56,8 @@ struct rcu_head {
 } while (0)
 
 
+extern bool rcu_always_quiesc;
+
 int rcu_pending(int cpu);
 int rcu_needs_cpu(int cpu);