vmm: Add CPU affinity support

With the introduction of a new option `affinity` to the `cpus`
parameter, Cloud Hypervisor can now let the user choose the set
of host CPUs where to run each vCPU.

This is useful when trying to achieve CPU pinning, as well as making
sure the VM runs on a specific NUMA node.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vmm/src/api/openapi/cloud-hypervisor.yaml

@@ -480,6 +480,16 @@ components:
           default: false
       description: Virtual machine configuration
 
+    CpuAffinity:
+      type: object
+      properties:
+        vcpu:
+          type: integer
+        host_cpus:
+          type: array
+          items:
+            type: integer
+
     CpuTopology:
       type: object
       properties:
@@ -507,9 +517,13 @@ components:
           default: 1
           type: integer
         topology:
-            $ref: '#/components/schemas/CpuTopology'
+          $ref: '#/components/schemas/CpuTopology'
         max_phys_bits:
           type: integer
+        affinity:
+          type: array
+          items:
+            $ref: '#/components/schemas/CpuAffinity'
 
     MemoryZoneConfig:
       required: