vm-virtio: Modify VirtioInterrupt callback into a trait

Callbacks are not the most Rust idiomatic way of programming. The right
way is to use a Trait to provide multiple implementation of the same
interface.

Additionally, a Trait will allow for multiple functions to be defined
while using callbacks means that a new callback must be introduced for
each new function we want to add.

For these two reasons, the current commit modifies the existing
VirtioInterrupt callback into a Trait of the same name.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vm-virtio/src/vhost_user/blk.rs

@@ -46,7 +46,7 @@ pub struct Blk {
     config_space: Vec<u8>,
     queue_sizes: Vec<u16>,
     queue_evts: Option<Vec<EventFd>>,
-    interrupt_cb: Option<Arc<VirtioInterrupt>>,
+    interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
     epoll_thread: Option<thread::JoinHandle<result::Result<(), DeviceError>>>,
     paused: Arc<AtomicBool>,
 }
@@ -220,7 +220,7 @@ impl VirtioDevice for Blk {
     fn activate(
         &mut self,
         mem: Arc<ArcSwap<GuestMemoryMmap>>,
-        interrupt_cb: Arc<VirtioInterrupt>,
+        interrupt_cb: Arc<dyn VirtioInterrupt>,
         queues: Vec<Queue>,
         queue_evts: Vec<EventFd>,
     ) -> ActivateResult {
@@ -285,7 +285,7 @@ impl VirtioDevice for Blk {
         Ok(())
     }
 
-    fn reset(&mut self) -> Option<(Arc<VirtioInterrupt>, Vec<EventFd>)> {
+    fn reset(&mut self) -> Option<(Arc<dyn VirtioInterrupt>, Vec<EventFd>)> {
         // We first must resume the virtio thread if it was paused.
         if self.pause_evt.take().is_some() {
             self.resume().ok()?;

vm-virtio/src/vhost_user/fs.rs

@@ -161,7 +161,7 @@ pub struct Fs {
     cache: Option<(VirtioSharedMemoryList, u64)>,
     slave_req_support: bool,
     queue_evts: Option<Vec<EventFd>>,
-    interrupt_cb: Option<Arc<VirtioInterrupt>>,
+    interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
     epoll_thread: Option<thread::JoinHandle<result::Result<(), DeviceError>>>,
     paused: Arc<AtomicBool>,
 }
@@ -333,7 +333,7 @@ impl VirtioDevice for Fs {
     fn activate(
         &mut self,
         mem: Arc<ArcSwap<GuestMemoryMmap>>,
-        interrupt_cb: Arc<VirtioInterrupt>,
+        interrupt_cb: Arc<dyn VirtioInterrupt>,
         queues: Vec<Queue>,
         queue_evts: Vec<EventFd>,
     ) -> ActivateResult {
@@ -431,7 +431,7 @@ impl VirtioDevice for Fs {
         Ok(())
     }
 
-    fn reset(&mut self) -> Option<(Arc<VirtioInterrupt>, Vec<EventFd>)> {
+    fn reset(&mut self) -> Option<(Arc<dyn VirtioInterrupt>, Vec<EventFd>)> {
         // We first must resume the virtio thread if it was paused.
         if self.pause_evt.take().is_some() {
             self.resume().ok()?;

vm-virtio/src/vhost_user/handler.rs

@@ -28,7 +28,7 @@ use vhost_rs::vhost_user::{MasterReqHandler, VhostUserMasterReqHandler};
 /// * `kill_evt` - EventFd used to kill the vhost-user device.
 /// * `vu_interrupt_list` - virtqueue and EventFd to signal when buffer used.
 pub struct VhostUserEpollConfig<S: VhostUserMasterReqHandler> {
-    pub interrupt_cb: Arc<VirtioInterrupt>,
+    pub interrupt_cb: Arc<dyn VirtioInterrupt>,
     pub kill_evt: EventFd,
     pub pause_evt: EventFd,
     pub vu_interrupt_list: Vec<(EventFd, Queue)>,
@@ -52,7 +52,9 @@ impl<S: VhostUserMasterReqHandler> VhostUserEpollHandler<S> {
     }
 
     fn signal_used_queue(&self, queue: &Queue) -> Result<()> {
-        (self.vu_epoll_cfg.interrupt_cb)(&VirtioInterruptType::Queue, Some(queue))
+        self.vu_epoll_cfg
+            .interrupt_cb
+            .trigger(&VirtioInterruptType::Queue, Some(queue))
             .map_err(Error::FailedSignalingUsedQueue)
     }
 

vm-virtio/src/vhost_user/net.rs

@@ -44,7 +44,7 @@ pub struct Net {
     config_space: Vec<u8>,
     queue_sizes: Vec<u16>,
     queue_evts: Option<Vec<EventFd>>,
-    interrupt_cb: Option<Arc<VirtioInterrupt>>,
+    interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
     epoll_thread: Option<Vec<thread::JoinHandle<result::Result<(), DeviceError>>>>,
     ctrl_queue_epoll_thread: Option<thread::JoinHandle<result::Result<(), CtrlError>>>,
     paused: Arc<AtomicBool>,
@@ -227,7 +227,7 @@ impl VirtioDevice for Net {
     fn activate(
         &mut self,
         mem: Arc<ArcSwap<GuestMemoryMmap>>,
-        interrupt_cb: Arc<VirtioInterrupt>,
+        interrupt_cb: Arc<dyn VirtioInterrupt>,
         mut queues: Vec<Queue>,
         mut queue_evts: Vec<EventFd>,
     ) -> ActivateResult {
@@ -336,7 +336,7 @@ impl VirtioDevice for Net {
         Ok(())
     }
 
-    fn reset(&mut self) -> Option<(Arc<VirtioInterrupt>, Vec<EventFd>)> {
+    fn reset(&mut self) -> Option<(Arc<dyn VirtioInterrupt>, Vec<EventFd>)> {
         // We first must resume the virtio thread if it was paused.
         if self.pause_evt.take().is_some() {
             self.resume().ok()?;