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/config.rs

@@ -398,6 +398,12 @@ impl FromStr for HotplugMethod {
     }
 }
 
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+pub struct CpuAffinity {
+    pub vcpu: u8,
+    pub host_cpus: Vec<u8>,
+}
+
 pub enum CpuTopologyParseError {
     InvalidValue(String),
 }
@@ -453,6 +459,8 @@ pub struct CpusConfig {
     pub kvm_hyperv: bool,
     #[serde(default = "default_cpuconfig_max_phys_bits")]
     pub max_phys_bits: u8,
+    #[serde(default)]
+    pub affinity: Option<Vec<CpuAffinity>>,
 }
 
 impl CpusConfig {
@@ -463,7 +471,8 @@ impl CpusConfig {
             .add("max")
             .add("topology")
             .add("kvm_hyperv")
-            .add("max_phys_bits");
+            .add("max_phys_bits")
+            .add("affinity");
         parser.parse(cpus).map_err(Error::ParseCpus)?;
 
         let boot_vcpus: u8 = parser
@@ -484,6 +493,17 @@ impl CpusConfig {
             .convert::<u8>("max_phys_bits")
             .map_err(Error::ParseCpus)?
             .unwrap_or(DEFAULT_MAX_PHYS_BITS);
+        let affinity = parser
+            .convert::<Tuple<u8, Vec<u8>>>("affinity")
+            .map_err(Error::ParseCpus)?
+            .map(|v| {
+                v.0.iter()
+                    .map(|(e1, e2)| CpuAffinity {
+                        vcpu: *e1,
+                        host_cpus: e2.clone(),
+                    })
+                    .collect()
+            });
 
         Ok(CpusConfig {
             boot_vcpus,
@@ -491,6 +511,7 @@ impl CpusConfig {
             topology,
             kvm_hyperv,
             max_phys_bits,
+            affinity,
         })
     }
 }
@@ -503,6 +524,7 @@ impl Default for CpusConfig {
             topology: None,
             kvm_hyperv: false,
             max_phys_bits: DEFAULT_MAX_PHYS_BITS,
+            affinity: None,
         }
     }
 }