vmm: Add 'hotplug_size' to memory zones

In anticipation for resizing support of an individual memory zone,
this commit introduces a new option 'hotplug_size' to '--memory-zone'
parameter. This defines the amount of memory that can be added through
each specific memory zone.

Because memory zone resize is tied to virtio-mem, make sure the user
selects 'virtio-mem' hotplug method, otherwise return an error.

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

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

@@ -477,6 +477,9 @@ components:
         host_numa_node:
           type: integer
           format: uint32
+        hotplug_size:
+          type: integer
+          format: int64
 
     MemoryConfig:
       required:

vmm/src/config.rs

@@ -379,6 +379,8 @@ pub struct MemoryZoneConfig {
     pub hugepages: bool,
     #[serde(default)]
     pub host_numa_node: Option<u32>,
+    #[serde(default)]
+    pub hotplug_size: Option<u64>,
 }
 
 #[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
@@ -460,7 +462,8 @@ impl MemoryConfig {
                     .add("file")
                     .add("shared")
                     .add("hugepages")
-                    .add("host_numa_node");
+                    .add("host_numa_node")
+                    .add("hotplug_size");
                 parser.parse(memory_zone).map_err(Error::ParseMemoryZone)?;
 
                 let id = parser.get("id").ok_or(Error::ParseMemoryZoneIdMissing)?;
@@ -483,6 +486,10 @@ impl MemoryConfig {
                 let host_numa_node = parser
                     .convert::<u32>("host_numa_node")
                     .map_err(Error::ParseMemoryZone)?;
+                let hotplug_size = parser
+                    .convert::<ByteSized>("hotplug_size")
+                    .map_err(Error::ParseMemoryZone)?
+                    .map(|v| v.0);
 
                 zones.push(MemoryZoneConfig {
                     id,
@@ -491,6 +498,7 @@ impl MemoryConfig {
                     shared,
                     hugepages,
                     host_numa_node,
+                    hotplug_size,
                 });
             }
             Some(zones)

vmm/src/memory_manager.rs

@@ -215,6 +215,9 @@ pub enum Error {
 
     /// Invalid size for resizing. Can be anything except 0.
     InvalidHotplugSize,
+
+    /// Invalid hotplug method associated with memory zones resizing capability.
+    InvalidHotplugMethodWithMemoryZones,
 }
 
 const ENABLE_FLAG: usize = 0;
@@ -442,6 +445,7 @@ impl MemoryManager {
                 shared: config.shared,
                 hugepages: config.hugepages,
                 host_numa_node: None,
+                hotplug_size: config.hotplug_size,
             }];
 
             (config.size, zones)
@@ -472,6 +476,11 @@ impl MemoryManager {
                     );
                     return Err(Error::InvalidSharedMemoryZoneWithHostNuma);
                 }
+
+                if zone.hotplug_size.is_some() && config.hotplug_method == HotplugMethod::Acpi {
+                    error!("Invalid to set ACPI hotplug method for memory zones");
+                    return Err(Error::InvalidHotplugMethodWithMemoryZones);
+                }
             }
 
             (total_ram_size, zones)