devices: virtio: use signal helper for config changes

Add handling of the virtio device MSI-X configuration change vector by
using the signal function that was previously factored out.

BUG=chromium:854765
TEST=./build_test
TEST=trigger disk config change with `crosvm disk resize ...`

Change-Id: I462c23e10d152f896586bb70b95634a53088d480
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1898269
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Zide Chen <zide.chen@intel.corp-partner.google.com>
Reviewed-by: Zach Reizner <zachr@chromium.org>

devices/src/virtio/interrupt.rs

@@ -14,6 +14,7 @@ pub struct Interrupt {
     interrupt_evt: EventFd,
     interrupt_resample_evt: EventFd,
     msix_config: Option<Arc<Mutex<MsixConfig>>>,
+    config_msix_vector: u16,
 }
 
 impl Interrupt {
@@ -22,12 +23,14 @@ impl Interrupt {
         interrupt_evt: EventFd,
         interrupt_resample_evt: EventFd,
         msix_config: Option<Arc<Mutex<MsixConfig>>>,
+        config_msix_vector: u16,
     ) -> Interrupt {
         Interrupt {
             interrupt_status,
             interrupt_evt,
             interrupt_resample_evt,
             msix_config,
+            config_msix_vector,
         }
     }
 
@@ -64,12 +67,9 @@ impl Interrupt {
         self.signal(vector, INTERRUPT_STATUS_USED_RING)
     }
 
-    /// Notification of Device Configuration Changes
-    /// Set BIT1 in ISR and write to irqfd
+    /// Notify the driver that the device configuration has changed.
     pub fn signal_config_changed(&self) {
-        self.interrupt_status
-            .fetch_or(INTERRUPT_STATUS_CONFIG_CHANGED as usize, Ordering::SeqCst);
-        self.interrupt_evt.write(1).unwrap();
+        self.signal(self.config_msix_vector, INTERRUPT_STATUS_CONFIG_CHANGED)
     }
 
     /// Handle interrupt resampling event

devices/src/virtio/vhost/net.rs

@@ -233,6 +233,7 @@ where
 #[cfg(test)]
 pub mod tests {
     use super::*;
+    use crate::virtio::VIRTIO_MSI_NO_VECTOR;
     use net_util::fakes::FakeTap;
     use std::result;
     use std::sync::atomic::AtomicUsize;
@@ -295,6 +296,7 @@ pub mod tests {
                 EventFd::new().unwrap(),
                 EventFd::new().unwrap(),
                 None,
+                VIRTIO_MSI_NO_VECTOR,
             ),
             vec![Queue::new(1)],
             vec![EventFd::new().unwrap()],

devices/src/virtio/virtio_pci_device.rs

@@ -618,6 +618,7 @@ impl PciDevice for VirtioPciDevice {
                             interrupt_evt,
                             interrupt_resample_evt,
                             msix_config,
+                            self.common_config.msix_config,
                         );
 
                         self.device.activate(

fuzz/block_fuzzer.rs

@@ -88,7 +88,8 @@ fuzz_target!(|bytes| {
             Arc::new(AtomicUsize::new(0)),
             EventFd::new().unwrap(),
             EventFd::new().unwrap(),
-            None, // msix_config
+            None,   // msix_config
+            0xFFFF, // VIRTIO_MSI_NO_VECTOR
         ),
         vec![q],
         queue_evts,