Add runnable vcpu

Add a new type `RunnableVcpu` for a vcpu that is bound to a thread. This
adds type safety to ensure that vcpus are only ever run on one thread
because RunnableVcpu can't `Send`. It also ensures multiple vcpus can't
run on the same thread.

Change-Id: Ia50dc127bc7a4ea4ce3ca99ef1062edbcaa912d0
Signed-off-by: Dylan Reid <dgreid@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1898909
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Zach Reizner <zachr@chromium.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/src/plugin/mod.rs b/src/plugin/mod.rs
index f0d6932..5f9a5db 100644
--- a/src/plugin/mod.rs
+++ b/src/plugin/mod.rs
@@ -420,7 +420,7 @@ pub fn run_vcpus(
         let vcpu_thread_barrier = vcpu_thread_barrier.clone();
         let vcpu_exit_evt = exit_evt.try_clone().map_err(Error::CloneEventFd)?;
         let vcpu_plugin = plugin.create_vcpu(cpu_id)?;
-        let mut vcpu = Vcpu::new(cpu_id as c_ulong, kvm, vm).map_err(Error::CreateVcpu)?;
+        let vcpu = Vcpu::new(cpu_id as c_ulong, kvm, vm).map_err(Error::CreateVcpu)?;
 
         vcpu_handles.push(
             thread::Builder::new()
@@ -431,10 +431,12 @@ pub fn run_vcpus(
                         // because we will be using first RT signal to kick the VCPU.
                         vcpu.set_signal_mask(&[])
                             .expect("failed to set up KVM VCPU signal mask");
-                    } else {
-                        vcpu.set_thread_id(SIGRTMIN() + 0);
                     }
 
+                    let vcpu = vcpu
+                        .to_runnable(Some(SIGRTMIN() + 0))
+                        .expect("Failed to set thread id");
+
                     let res = vcpu_plugin.init(&vcpu);
                     vcpu_thread_barrier.wait();
                     if let Err(e) = res {