refactor: move kick signal registration to Vcpu

Let vcpus register the signal handler instead of doing
this manually. This way the thread local is guarantied to
be set before new signal handler is able to run.

Signed-off-by: Egor Lazarchuk <[email protected]>

Author: ShadowCurse

src/vmm/src/lib.rs

@@ -375,8 +375,6 @@ impl Vmm {
             })?;
         }
 
-        Vcpu::register_kick_signal_handler();
-
         self.vcpus_handles.reserve(vcpu_count);
 
         for mut vcpu in vcpus.drain(..) {

src/vmm/src/vstate/vcpu.rs

@@ -146,7 +146,9 @@ impl Vcpu {
 
     /// Registers a signal handler which makes use of TLS and kvm immediate exit to
     /// kick the vcpu running on the current thread, if there is one.
-    pub fn register_kick_signal_handler() {
+    pub fn register_kick_signal_handler(&mut self) {
+        self.init_thread_local_data();
+
         extern "C" fn handle_signal(_: c_int, _: *mut siginfo_t, _: *mut c_void) {
             // SAFETY: This is safe because it's temporarily aliasing the `Vcpu` object, but we are
             // only reading `vcpu.fd` which does not change for the lifetime of the `Vcpu`.
@@ -222,7 +224,7 @@ impl Vcpu {
             .name(format!("fc_vcpu {}", self.kvm_vcpu.index))
             .spawn(move || {
                 let filter = &*seccomp_filter;
-                self.init_thread_local_data();
+                self.register_kick_signal_handler();
                 // Synchronization to make sure thread local data is initialized.
                 barrier.wait();
                 self.run(filter);
@@ -920,7 +922,6 @@ pub(crate) mod tests {
     }
 
     fn vcpu_configured_for_boot() -> (Vm, VcpuHandle, EventFd) {
-        Vcpu::register_kick_signal_handler();
         // Need enough mem to boot linux.
         let mem_size = mib_to_bytes(64);
         let (kvm, vm, mut vcpu) = setup_vcpu(mem_size);
@@ -1021,7 +1022,6 @@ pub(crate) mod tests {
 
     #[test]
     fn test_vcpu_kick() {
-        Vcpu::register_kick_signal_handler();
         let (_, vm, mut vcpu) = setup_vcpu(0x1000);
 
         let mut kvm_run =
@@ -1035,7 +1035,7 @@ pub(crate) mod tests {
         let handle = std::thread::Builder::new()
             .name("test_vcpu_kick".to_string())
             .spawn(move || {
-                vcpu.init_thread_local_data();
+                vcpu.register_kick_signal_handler();
                 // Notify TLS was populated.
                 vcpu_barrier.wait();
                 // Loop for max 1 second to check if the signal handler has run.