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>

tests/integration.rs

@@ -2575,7 +2575,63 @@ mod common_parallel {
 
         let _ = child.kill();
         let output = child.wait_with_output().unwrap();
+        handle_child_output(r, &output);
+    }
 
+    #[test]
+    fn test_virtio_queue_affinity() {
+        let focal = UbuntuDiskConfig::new(FOCAL_IMAGE_NAME.to_string());
+        let guest = Guest::new(Box::new(focal));
+
+        // We need the host to have at least 4 CPUs if we want to be able
+        // to run this test.
+        let host_cpus_count = exec_host_command_output("nproc");
+        assert!(
+            String::from_utf8_lossy(&host_cpus_count.stdout)
+                .trim()
+                .parse::<u16>()
+                .unwrap_or(0)
+                >= 4
+        );
+
+        let mut child = GuestCommand::new(&guest)
+            .args(["--cpus", "boot=4"])
+            .args(["--memory", "size=512M"])
+            .args(["--kernel", direct_kernel_boot_path().to_str().unwrap()])
+            .args(["--cmdline", DIRECT_KERNEL_BOOT_CMDLINE])
+            .args([
+                "--disk",
+                format!(
+                    "path={}",
+                    guest.disk_config.disk(DiskType::OperatingSystem).unwrap()
+                )
+                .as_str(),
+                format!(
+                    "path={},num_queues=4,queue_affinity=[0@[0,2],1@[1,3],2@[1],3@[3]]",
+                    guest.disk_config.disk(DiskType::CloudInit).unwrap()
+                )
+                .as_str(),
+            ])
+            .default_net()
+            .capture_output()
+            .spawn()
+            .unwrap();
+
+        let r = std::panic::catch_unwind(|| {
+            guest.wait_vm_boot(None).unwrap();
+            let pid = child.id();
+            let taskset_q0 = exec_host_command_output(format!("taskset -pc $(ps -T -p {pid} | grep disk1_q0 | xargs | cut -f 2 -d \" \") | cut -f 6 -d \" \"").as_str());
+            assert_eq!(String::from_utf8_lossy(&taskset_q0.stdout).trim(), "0,2");
+            let taskset_q1 = exec_host_command_output(format!("taskset -pc $(ps -T -p {pid} | grep disk1_q1 | xargs | cut -f 2 -d \" \") | cut -f 6 -d \" \"").as_str());
+            assert_eq!(String::from_utf8_lossy(&taskset_q1.stdout).trim(), "1,3");
+            let taskset_q2 = exec_host_command_output(format!("taskset -pc $(ps -T -p {pid} | grep disk1_q2 | xargs | cut -f 2 -d \" \") | cut -f 6 -d \" \"").as_str());
+            assert_eq!(String::from_utf8_lossy(&taskset_q2.stdout).trim(), "1");
+            let taskset_q3 = exec_host_command_output(format!("taskset -pc $(ps -T -p {pid} | grep disk1_q3 | xargs | cut -f 2 -d \" \") | cut -f 6 -d \" \"").as_str());
+            assert_eq!(String::from_utf8_lossy(&taskset_q3.stdout).trim(), "3");
+        });
+
+        let _ = child.kill();
+        let output = child.wait_with_output().unwrap();
         handle_child_output(r, &output);
     }