2 files changed, 62 insertions, 29 deletions

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index d8b64ba45b1d..bbd812e87511 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -356,8 +356,9 @@ void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid)
          * We need to free the bit for init_vp_index() to work in the case
          * of sub-channel, when we reload drivers like hv_netvsc.
          */
-        cpumask_clear_cpu(channel->target_cpu,
-                          &primary_channel->alloced_cpus_in_node);
+        if (channel->affinity_policy == HV_LOCALIZED)
+                cpumask_clear_cpu(channel->target_cpu,
+                                  &primary_channel->alloced_cpus_in_node);
 
         vmbus_release_relid(relid);
 
@@ -548,17 +549,17 @@ static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
         }
 
         /*
-         * We distribute primary channels evenly across all the available
-         * NUMA nodes and within the assigned NUMA node we will assign the
-         * first available CPU to the primary channel.
-         * The sub-channels will be assigned to the CPUs available in the
-         * NUMA node evenly.
+         * Based on the channel affinity policy, we will assign the NUMA
+         * nodes.
          */
-        if (!primary) {
+
+        if ((channel->affinity_policy == HV_BALANCED) || (!primary)) {
                 while (true) {
                         next_node = next_numa_node_id++;
-                        if (next_node == nr_node_ids)
+                        if (next_node == nr_node_ids) {
                                 next_node = next_numa_node_id = 0;
+                                continue;
+                        }
                         if (cpumask_empty(cpumask_of_node(next_node)))
                                 continue;
                         break;
@@ -582,15 +583,17 @@ static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
 
         cur_cpu = -1;
 
-        /*
-         * Normally Hyper-V host doesn't create more subchannels than there
-         * are VCPUs on the node but it is possible when not all present VCPUs
-         * on the node are initialized by guest. Clear the alloced_cpus_in_node
-         * to start over.
-         */
-        if (cpumask_equal(&primary->alloced_cpus_in_node,
-                          cpumask_of_node(primary->numa_node)))
-                cpumask_clear(&primary->alloced_cpus_in_node);
+        if (primary->affinity_policy == HV_LOCALIZED) {
+                /*
+                 * Normally Hyper-V host doesn't create more subchannels
+                 * than there are VCPUs on the node but it is possible when not
+                 * all present VCPUs on the node are initialized by guest.
+                 * Clear the alloced_cpus_in_node to start over.
+                 */
+                if (cpumask_equal(&primary->alloced_cpus_in_node,
+                                  cpumask_of_node(primary->numa_node)))
+                        cpumask_clear(&primary->alloced_cpus_in_node);
+        }
 
         while (true) {
                 cur_cpu = cpumask_next(cur_cpu, &available_mask);
@@ -601,17 +604,24 @@ static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
                         continue;
                 }
 
-                /*
-                 * NOTE: in the case of sub-channel, we clear the sub-channel
-                 * related bit(s) in primary->alloced_cpus_in_node in
-                 * hv_process_channel_removal(), so when we reload drivers
-                 * like hv_netvsc in SMP guest, here we're able to re-allocate
-                 * bit from primary->alloced_cpus_in_node.
-                 */
-                if (!cpumask_test_cpu(cur_cpu,
-                                &primary->alloced_cpus_in_node)) {
-                        cpumask_set_cpu(cur_cpu,
-                                        &primary->alloced_cpus_in_node);
+                if (primary->affinity_policy == HV_LOCALIZED) {
+                        /*
+                         * NOTE: in the case of sub-channel, we clear the
+                         * sub-channel related bit(s) in
+                         * primary->alloced_cpus_in_node in
+                         * hv_process_channel_removal(), so when we
+                         * reload drivers like hv_netvsc in SMP guest, here
+                         * we're able to re-allocate
+                         * bit from primary->alloced_cpus_in_node.
+                         */
+                        if (!cpumask_test_cpu(cur_cpu,
+                                              &primary->alloced_cpus_in_node)) {
+                                cpumask_set_cpu(cur_cpu,
+                                                &primary->alloced_cpus_in_node);
+                                cpumask_set_cpu(cur_cpu, alloced_mask);
+                                break;
+                        }
+                } else {
                         cpumask_set_cpu(cur_cpu, alloced_mask);
                         break;
                 }
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index e6ef571e6100..c877e7980585 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -674,6 +674,11 @@ enum hv_signal_policy {
         HV_SIGNAL_POLICY_EXPLICIT,
 };
 
+enum hv_numa_policy {
+        HV_BALANCED = 0,
+        HV_LOCALIZED,
+};
+
 enum vmbus_device_type {
         HV_IDE = 0,
         HV_SCSI,
@@ -876,6 +881,18 @@ struct vmbus_channel {
          */
         bool low_latency;
 
+        /*
+         * NUMA distribution policy:
+         * We support teo policies:
+         * 1) Balanced: Here all performance critical channels are
+         *    distributed evenly amongst all the NUMA nodes.
+         *    This policy will be the default policy.
+         * 2) Localized: All channels of a given instance of a
+         *    performance critical service will be assigned CPUs
+         *    within a selected NUMA node.
+         */
+        enum hv_numa_policy affinity_policy;
+
 };
 
 static inline void set_channel_lock_state(struct vmbus_channel *c, bool state)
@@ -895,6 +912,12 @@ static inline void set_channel_signal_state(struct vmbus_channel *c,
         c->signal_policy = policy;
 }
 
+static inline void set_channel_affinity_state(struct vmbus_channel *c,
+                                              enum hv_numa_policy policy)
+{
+        c->affinity_policy = policy;
+}
+
 static inline void set_channel_read_state(struct vmbus_channel *c, bool state)
 {
         c->batched_reading = state;