virtio-devices: Make reset() best-effort on backend failures

The virtio specification treats reset as the recovery operation and so
must take the device back to a fresh state, and the driver waits for the
status read-back to converge before continuing. There is no defined way
for the device to report a reset failure to the driver.

Previously the implementations of reset() would return early and not
complete all their cleanup leaving them in an inconsistent state. Now
log errors and continue through the execution.

Signed-off-by: Rob Bradford <rbradford@meta.com>
Assisted-by: Claude:claude-opus-4-7

virtio-devices/src/vdpa.rs

@@ -451,9 +451,10 @@ impl VirtioDevice for Vdpa {
     }
 
     fn reset(&mut self) -> Option<Arc<dyn VirtioInterrupt>> {
+        // Backend reset failures are logged but don't skip local cleanup:
+        // reset must converge to fresh state regardless of backend state.
         if let Err(e) = self.reset_vdpa() {
             error!("Failed to reset vhost-vdpa: {e:?}");
-            return None;
         }
 
         event!("vdpa", "reset", "id", &self.id);