runtime-rs: Propagate and map discard as Dragonball sparse

Map BlockConfigModern.discard_unmap to Dragonball block device
sparse support when adding modern block devices.
This lets runtime-rs request guest-visible discard support through
the Dragonball block device configuration while leaving vhost-user
block devices disabled.

Signed-off-by: Alex Lyn <alex.lyn@antgroup.com>

src/dragonball/crates/dbs_virtio_devices/src/block/device.rs

@@ -700,6 +700,10 @@ mod tests {
             let mut q = vq.create_queue();
             data_descs.clear();
             // status desc read only
+            m.write_obj::<u32>(VIRTIO_BLK_T_GET_ID, GuestAddress(0x1000))
+                .unwrap();
+            vq.dtable(1)
+                .set(0x2000, 0x40, VIRTQ_DESC_F_NEXT | VIRTQ_DESC_F_WRITE, 2);
             vq.dtable(2).flags().store(0);
             assert!(matches!(
                 Request::parse(&mut q.pop_descriptor_chain(m).unwrap(), &mut data_descs, 32),
@@ -711,6 +715,10 @@ mod tests {
             let mut q = vq.create_queue();
             data_descs.clear();
             // status desc too small
+            m.write_obj::<u32>(VIRTIO_BLK_T_GET_ID, GuestAddress(0x1000))
+                .unwrap();
+            vq.dtable(1)
+                .set(0x2000, 0x40, VIRTQ_DESC_F_NEXT | VIRTQ_DESC_F_WRITE, 2);
             vq.dtable(2).flags().store(VIRTQ_DESC_F_WRITE);
             vq.dtable(2).len().store(0);
             assert!(matches!(
@@ -1032,6 +1040,7 @@ mod tests {
             let mut dev = Block::<Arc<GuestMemoryMmap<()>>>::new(
                 vec![disk_image],
                 true,
+                false,
                 Arc::new(vec![128]),
                 epoll_mgr.clone(),
                 vec![],
@@ -1146,6 +1155,7 @@ mod tests {
         let mut dev = Block::<Arc<GuestMemoryMmap>>::new(
             vec![disk_image],
             true,
+            false,
             Arc::new(vec![128]),
             epoll_mgr,
             vec![],

src/runtime-rs/crates/hypervisor/src/dragonball/inner_device.rs

@@ -70,6 +70,7 @@ impl DragonballInner {
                     no_drop,
                     is_direct,
                     driver_option,
+                    sparse,
                 ) = {
                     let dev = block_device.lock().await;
                     let cfg = &dev.config;
@@ -80,6 +81,7 @@ impl DragonballInner {
                         cfg.no_drop,
                         cfg.is_direct,
                         cfg.driver_option.clone(),
+                        cfg.discard_unmap,
                     )
                 };
 
@@ -106,13 +108,15 @@ impl DragonballInner {
                         no_drop,
                         is_direct,
                         use_pci_bus,
+                        sparse,
                     )
                     .context("add block modern device")?;
 
                 info!(
                     sl!(),
                     "BlockModern hotplug result: device_id={}, guest_device_id={:?}",
-                    device_id, guest_device_id
+                    device_id,
+                    guest_device_id
                 );
 
                 if let Some(slot) = guest_device_id {
@@ -132,6 +136,7 @@ impl DragonballInner {
                     block.no_drop,
                     None,
                     None,
+                    false,
                 )
                 .context("add vhost user based block device")?;
                 Ok(DeviceType::VhostUserBlk(block))
@@ -253,6 +258,7 @@ impl DragonballInner {
         Ok(())
     }
 
+    #[allow(clippy::too_many_arguments)]
     fn add_block_device(
         &mut self,
         path: &str,
@@ -261,6 +267,7 @@ impl DragonballInner {
         no_drop: bool,
         is_direct: Option<bool>,
         use_pci_bus: Option<bool>,
+        sparse: bool,
     ) -> Result<Option<i32>> {
         let jailed_drive = self.get_resource(path, id).context("get resource")?;
         self.cached_block_devices.insert(id.to_string());
@@ -294,6 +301,7 @@ impl DragonballInner {
             no_drop,
             is_read_only: read_only,
             use_pci_bus,
+            sparse,
             rate_limiter: Some(block_rate_limit),
             ..Default::default()
         };
@@ -311,7 +319,10 @@ impl DragonballInner {
             .insert_block_device(blk_cfg, Duration::from_millis(DEFAULT_HOTPLUG_TIMEOUT))
             .context("insert block device");
         match &result {
-            Ok(guest_id) => info!(sl!(), "add_block_device success: id={}, guest_id={:?}", id, guest_id),
+            Ok(guest_id) => info!(
+                sl!(),
+                "add_block_device success: id={}, guest_id={:?}", id, guest_id
+            ),
             Err(e) => error!(sl!(), "add_block_device failed: id={}, error={:?}", id, e),
         }
         result