[PATCH] domain: skip more stuff for idle's vCPU-s in vcpu_create()

[Jan Beulich <jbeulich@xxxxxxxx>]

Nothing hypercall-related needs setting up there. Nor do we need to
check whether the idle domain is shutting down - it never will.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
For vmtrace_alloc_buffer() adding the conditional may be questionable: The
function checks d->vmtrace_size first thing, bailing immediately when it's
zero (which it always will be for the idle domain).

--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -427,12 +427,6 @@ struct vcpu *vcpu_create(struct domain *
     v->vcpu_id = vcpu_id;
     v->dirty_cpu = VCPU_CPU_CLEAN;
 
-    rwlock_init(&v->virq_lock);
-
-    tasklet_init(&v->continue_hypercall_tasklet, NULL, NULL);
-
-    grant_table_init_vcpu(v);
-
     if ( is_idle_domain(d) )
     {
         v->runstate.state = RUNSTATE_running;
@@ -440,6 +434,12 @@ struct vcpu *vcpu_create(struct domain *
     }
     else
     {
+        rwlock_init(&v->virq_lock);
+
+        tasklet_init(&v->continue_hypercall_tasklet, NULL, NULL);
+
+        grant_table_init_vcpu(v);
+
         v->runstate.state = RUNSTATE_offline;
         v->runstate.state_entry_time = NOW();
         set_bit(_VPF_down, &v->pause_flags);
@@ -450,7 +450,7 @@ struct vcpu *vcpu_create(struct domain *
     if ( sched_init_vcpu(v) != 0 )
         goto fail_wq;
 
-    if ( vmtrace_alloc_buffer(v) != 0 )
+    if ( !is_idle_domain(d) && vmtrace_alloc_buffer(v) != 0 )
         goto fail_wq;
 
     if ( arch_vcpu_create(v) != 0 )
@@ -468,7 +468,8 @@ struct vcpu *vcpu_create(struct domain *
     }
 
     /* Must be called after making new vcpu visible to for_each_vcpu(). */
-    vcpu_check_shutdown(v);
+    if ( !is_idle_domain(d) )
+        vcpu_check_shutdown(v);
 
     return v;