virtio-devices: Use Default::default() for transitioning to VirtioCommon

In order to simplify the transition to VirtioCommon and to avoid needing
to set empty fields derive Default for VirtioCommon.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

virtio-devices/src/balloon.rs

@@ -333,7 +333,7 @@ impl Balloon {
         Ok(Balloon {
             common: VirtioCommon {
                 avail_features,
-                acked_features: 0u64,
+                ..Default::default()
             },
             id,
             resize: VirtioBalloonResize::new()?,

virtio-devices/src/block.rs

@@ -339,7 +339,7 @@ impl<T: DiskFile> Block<T> {
         Ok(Block {
             common: VirtioCommon {
                 avail_features,
-                acked_features: 0u64,
+                ..Default::default()
             },
             id,
             kill_evt: None,

virtio-devices/src/block_io_uring.rs

@@ -374,7 +374,7 @@ impl BlockIoUring {
         Ok(BlockIoUring {
             common: VirtioCommon {
                 avail_features,
-                acked_features: 0u64,
+                ..Default::default()
             },
             id,
             kill_evt: None,

virtio-devices/src/console.rs

@@ -352,7 +352,7 @@ impl Console {
             Console {
                 common: VirtioCommon {
                     avail_features,
-                    acked_features: 0u64,
+                    ..Default::default()
                 },
                 id,
                 kill_evt: None,

virtio-devices/src/device.rs

@@ -183,6 +183,7 @@ pub trait DmaRemapping: Send + Sync {
 }
 
 /// Structure to handle device state common to all devices
+#[derive(Default)]
 pub struct VirtioCommon {
     pub avail_features: u64,
     pub acked_features: u64,

virtio-devices/src/iommu.rs

@@ -782,7 +782,7 @@ impl Iommu {
                     avail_features: 1u64 << VIRTIO_F_VERSION_1
                         | 1u64 << VIRTIO_IOMMU_F_MAP_UNMAP
                         | 1u64 << VIRTIO_IOMMU_F_PROBE,
-                    acked_features: 0u64,
+                    ..Default::default()
                 },
                 config,
                 config_topo_pci_ranges: Vec::new(),

virtio-devices/src/mem.rs

@@ -738,7 +738,7 @@ impl Mem {
         Ok(Mem {
             common: VirtioCommon {
                 avail_features,
-                acked_features: 0u64,
+                ..Default::default()
             },
             id,
             resize,

virtio-devices/src/net.rs

@@ -259,7 +259,7 @@ impl Net {
         Ok(Net {
             common: VirtioCommon {
                 avail_features,
-                acked_features: 0u64,
+                ..Default::default()
             },
             id,
             kill_evt: None,

virtio-devices/src/pmem.rs

@@ -331,7 +331,7 @@ impl Pmem {
         Ok(Pmem {
             common: VirtioCommon {
                 avail_features,
-                acked_features: 0u64,
+                ..Default::default()
             },
             id,
             kill_evt: None,

virtio-devices/src/rng.rs

@@ -165,7 +165,7 @@ impl Rng {
         Ok(Rng {
             common: VirtioCommon {
                 avail_features,
-                acked_features: 0u64,
+                ..Default::default()
             },
             id,
             kill_evt: None,

virtio-devices/src/vhost_user/blk.rs

@@ -142,6 +142,7 @@ impl Blk {
             common: VirtioCommon {
                 avail_features,
                 acked_features,
+                ..Default::default()
             },
             id,
             vhost_user_blk,

virtio-devices/src/vhost_user/fs.rs

@@ -358,6 +358,7 @@ impl Fs {
             common: VirtioCommon {
                 avail_features,
                 acked_features,
+                ..Default::default()
             },
             id,
             vu: master,

virtio-devices/src/vhost_user/net.rs

@@ -151,6 +151,7 @@ impl Net {
             common: VirtioCommon {
                 avail_features,
                 acked_features,
+                ..Default::default()
             },
             vhost_user_net,
             kill_evt: None,

virtio-devices/src/vsock/device.rs

@@ -338,7 +338,7 @@ where
         Ok(Vsock {
             common: VirtioCommon {
                 avail_features,
-                acked_features: 0u64,
+                ..Default::default()
             },
             id,
             cid,