fix(tests/virtio-mem): increase base VM memory size to hotplug 16GB

The previously set 256MB were not enough for hotplugging 16GB of memory.
This is because the kernel needs 64B for every 4kB page, meaning 262MB
for 16GB.

Signed-off-by: Riccardo Mancini <mancio@amazon.com>

Author: Manciukic

tests/integration_tests/performance/test_hotplug_memory.py

@@ -35,15 +35,20 @@ def uvm_booted_memhp(
 
     uvm.spawn()
     uvm.memory_monitor = None
+    uvm_config = {
+        "boot_args": MEMHP_BOOTARGS,
+        "huge_pages": huge_pages,
+        # we need enough memory to be able to hotplug up to 16GB
+        "mem_size_mib": 512,
+    }
     if vhost_user:
         # We need to setup ssh keys manually because we did not specify rootfs
         # in microvm_factory.build method
         ssh_key = rootfs.with_suffix(".id_rsa")
         uvm.ssh_key = ssh_key
         uvm.basic_config(
-            boot_args=MEMHP_BOOTARGS,
+            **uvm_config,
             add_root_device=False,
-            huge_pages=huge_pages,
             track_dirty_pages=(
                 snapshot_type.needs_dirty_page_tracking if snapshot_type else False
             ),
@@ -52,7 +57,7 @@ def uvm_booted_memhp(
             "rootfs", rootfs, is_root_device=True, is_read_only=True
         )
     else:
-        uvm.basic_config(boot_args=MEMHP_BOOTARGS, huge_pages=huge_pages)
+        uvm.basic_config(**uvm_config)
 
     uvm.api.memory_hotplug.put(**memhp_config)
     uvm.add_net_iface()