xen/18509-continue-hypercall-on-cpu.patch

# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1221657190 -3600
# Node ID 366c78ff361bafb2271c551c4976e4caedea72b2
# Parent  beb28a3975bd39c93c7934dd5e7ec80c69a86c4a
x86: Allow continue_hypercall_on_cpu() to be called from within an
existing continuation handler. This fix is needed for the new method
of microcode re-programming.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

Index: xen-3.3.1-testing/xen/arch/x86/domain.c
===================================================================
--- xen-3.3.1-testing.orig/xen/arch/x86/domain.c
+++ xen-3.3.1-testing/xen/arch/x86/domain.c
@@ -1356,6 +1356,7 @@ struct migrate_info {
     void *data;
     void (*saved_schedule_tail)(struct vcpu *);
     cpumask_t saved_affinity;
+    unsigned int nest;
 };
 
 static void continue_hypercall_on_cpu_helper(struct vcpu *v)
@@ -1363,48 +1364,64 @@ static void continue_hypercall_on_cpu_he
     struct cpu_user_regs *regs = guest_cpu_user_regs();
     struct migrate_info *info = v->arch.continue_info;
     cpumask_t mask = info->saved_affinity;
+    void (*saved_schedule_tail)(struct vcpu *) = info->saved_schedule_tail;
 
     regs->eax = info->func(info->data);
 
-    v->arch.schedule_tail = info->saved_schedule_tail;
-    v->arch.continue_info = NULL;
-
-    xfree(info);
+    if ( info->nest-- == 0 )
+    {
+        xfree(info);
+        v->arch.schedule_tail = saved_schedule_tail;
+        v->arch.continue_info = NULL;
+        vcpu_unlock_affinity(v, &mask);
+    }
 
-    vcpu_unlock_affinity(v, &mask);
-    schedule_tail(v);
+    (*saved_schedule_tail)(v);
 }
 
 int continue_hypercall_on_cpu(int cpu, long (*func)(void *data), void *data)
 {
     struct vcpu *v = current;
     struct migrate_info *info;
+    cpumask_t mask = cpumask_of_cpu(cpu);
     int rc;
 
     if ( cpu == smp_processor_id() )
         return func(data);
 
-    info = xmalloc(struct migrate_info);
+    info = v->arch.continue_info;
     if ( info == NULL )
-        return -ENOMEM;
+    {
+        info = xmalloc(struct migrate_info);
+        if ( info == NULL )
+            return -ENOMEM;
 
-    info->func = func;
-    info->data = data;
-    info->saved_schedule_tail = v->arch.schedule_tail;
-    info->saved_affinity = cpumask_of_cpu(cpu);
+        rc = vcpu_lock_affinity(v, &mask);
+        if ( rc )
+        {
+            xfree(info);
+            return rc;
+        }
 
-    v->arch.schedule_tail = continue_hypercall_on_cpu_helper;
-    v->arch.continue_info = info;
+        info->saved_schedule_tail = v->arch.schedule_tail;
+        info->saved_affinity = mask;
+        info->nest = 0;
 
-    rc = vcpu_lock_affinity(v, &info->saved_affinity);
-    if ( rc )
+        v->arch.schedule_tail = continue_hypercall_on_cpu_helper;
+        v->arch.continue_info = info;
+    }
+    else
     {
-        v->arch.schedule_tail = info->saved_schedule_tail;
-        v->arch.continue_info = NULL;
-        xfree(info);
-        return rc;
+        BUG_ON(info->nest != 0);
+        rc = vcpu_locked_change_affinity(v, &mask);
+        if ( rc )
+            return rc;
+        info->nest++;
     }
 
+    info->func = func;
+    info->data = data;
+
     /* Dummy return value will be overwritten by new schedule_tail. */
     BUG_ON(!test_bit(SCHEDULE_SOFTIRQ, &softirq_pending(smp_processor_id())));
     return 0;
Index: xen-3.3.1-testing/xen/common/schedule.c
===================================================================
--- xen-3.3.1-testing.orig/xen/common/schedule.c
+++ xen-3.3.1-testing/xen/common/schedule.c
@@ -360,6 +360,11 @@ int vcpu_lock_affinity(struct vcpu *v, c
     return __vcpu_set_affinity(v, affinity, 0, 1);
 }
 
+int vcpu_locked_change_affinity(struct vcpu *v, cpumask_t *affinity)
+{
+    return __vcpu_set_affinity(v, affinity, 1, 1);
+}
+
 void vcpu_unlock_affinity(struct vcpu *v, cpumask_t *affinity)
 {
     cpumask_t online_affinity;
Index: xen-3.3.1-testing/xen/include/xen/sched.h
===================================================================
--- xen-3.3.1-testing.orig/xen/include/xen/sched.h
+++ xen-3.3.1-testing/xen/include/xen/sched.h
@@ -534,6 +534,7 @@ void vcpu_force_reschedule(struct vcpu *
 void cpu_disable_scheduler(void);
 int vcpu_set_affinity(struct vcpu *v, cpumask_t *affinity);
 int vcpu_lock_affinity(struct vcpu *v, cpumask_t *affinity);
+int vcpu_locked_change_affinity(struct vcpu *v, cpumask_t *affinity);
 void vcpu_unlock_affinity(struct vcpu *v, cpumask_t *affinity);
 
 void vcpu_runstate_get(struct vcpu *v, struct vcpu_runstate_info *runstate);