block: Set an option to pin virtio block threads to host cpus

Currently the only way to set the affinity for virtio block threads is
to boot the VM, search for the tid of each of the virtio block threads,
then set the affinity manually. This commit adds an option to pin virtio
block queues to specific host cpus (similar to pinning vcpus to host
cpus). A queue_affinity option has been added to the disk flag in
the cli to specify a mapping of queue indices to host cpus.

Signed-off-by: acarp <acarp@crusoeenergy.com>

vmm/src/vm_config.rs

@@ -187,6 +187,12 @@ pub struct RateLimiterGroupConfig {
     pub rate_limiter_config: RateLimiterConfig,
 }
 
+#[derive(Clone, Debug, PartialEq, Eq, Deserialize, Serialize)]
+pub struct VirtQueueAffinity {
+    pub queue_index: u16,
+    pub host_cpus: Vec<usize>,
+}
+
 #[derive(Clone, Debug, PartialEq, Eq, Deserialize, Serialize)]
 pub struct DiskConfig {
     pub path: Option<PathBuf>,
@@ -219,6 +225,8 @@ pub struct DiskConfig {
     pub pci_segment: u16,
     #[serde(default)]
     pub serial: Option<String>,
+    #[serde(default)]
+    pub queue_affinity: Option<Vec<VirtQueueAffinity>>,
 }
 
 pub const DEFAULT_DISK_NUM_QUEUES: usize = 1;