References: bsc#991934

# Commit d5438accceecc8172db2d37d98b695eb8bc43afc
# Date 2016-07-26 10:44:06 +0100
# Author George Dunlap <george.dunlap@citrix.com>
# Committer George Dunlap <george.dunlap@citrix.com>
xen: Remove buggy initial placement algorithm

The initial placement algorithm sometimes picks cpus outside of the
mask it's given, does a lot of unnecessary bitmasking, does its own
separate load calculation, and completely ignores vcpu hard and soft
affinities.  Just get rid of it and rely on the schedulers to do
initial placement.

Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -217,54 +217,6 @@ void getdomaininfo(struct domain *d, str
     memcpy(info->handle, d->handle, sizeof(xen_domain_handle_t));
 }
 
-static unsigned int default_vcpu0_location(cpumask_t *online)
-{
-    struct domain *d;
-    struct vcpu   *v;
-    unsigned int   i, cpu, nr_cpus, *cnt;
-    cpumask_t      cpu_exclude_map;
-
-    /* Do an initial CPU placement. Pick the least-populated CPU. */
-    nr_cpus = cpumask_last(&cpu_online_map) + 1;
-    cnt = xzalloc_array(unsigned int, nr_cpus);
-    if ( cnt )
-    {
-        rcu_read_lock(&domlist_read_lock);
-        for_each_domain ( d )
-            for_each_vcpu ( d, v )
-                if ( !(v->pause_flags & VPF_down)
-                     && ((cpu = v->processor) < nr_cpus) )
-                    cnt[cpu]++;
-        rcu_read_unlock(&domlist_read_lock);
-    }
-
-    /*
-     * If we're on a HT system, we only auto-allocate to a non-primary HT. We
-     * favour high numbered CPUs in the event of a tie.
-     */
-    cpumask_copy(&cpu_exclude_map, per_cpu(cpu_sibling_mask, 0));
-    cpu = cpumask_first(&cpu_exclude_map);
-    i = cpumask_next(cpu, &cpu_exclude_map);
-    if ( i < nr_cpu_ids )
-        cpu = i;
-    for_each_cpu(i, online)
-    {
-        if ( cpumask_test_cpu(i, &cpu_exclude_map) )
-            continue;
-        if ( (i == cpumask_first(per_cpu(cpu_sibling_mask, i))) &&
-             (cpumask_next(i, per_cpu(cpu_sibling_mask, i)) < nr_cpu_ids) )
-            continue;
-        cpumask_or(&cpu_exclude_map, &cpu_exclude_map,
-                   per_cpu(cpu_sibling_mask, i));
-        if ( !cnt || cnt[i] <= cnt[cpu] )
-            cpu = i;
-    }
-
-    xfree(cnt);
-
-    return cpu;
-}
-
 bool_t domctl_lock_acquire(void)
 {
     /*
@@ -691,7 +643,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xe
                 continue;
 
             cpu = (i == 0) ?
-                default_vcpu0_location(online) :
+                cpumask_any(online) :
                 cpumask_cycle(d->vcpu[i-1]->processor, online);
 
             if ( alloc_vcpu(d, i, cpu) == NULL )