crosvm: allow several video devices to be instantiated

There is no technical reason to limit the number of video decoders and
encoders that can be instantiated, so remove the current artificial
limitation of one.

BUG=b:255223604
TEST=`cargo run --features "video-decoder,ffmpeg,vaapi" -- ... --video-decoder ffmpeg --video-decoder vaapi`
results in two usable decoder devices in the guest.

Change-Id: I71cd344db6827b57daa324ccb467425fe8337b65
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/3974354
Commit-Queue: Alexandre Courbot <acourbot@chromium.org>
Reviewed-by: Dennis Kempin <denniskempin@google.com>
Reviewed-by: Keiichi Watanabe <keiichiw@chromium.org>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>

src/crosvm/cmdline.rs

@@ -1601,7 +1601,7 @@ pub struct RunCommand {
     #[argh(option, arg_name = "SOCKET_PATH")]
     #[serde(skip)] // TODO(b/255223604)
     /// path to a socket for vhost-user video decoder
-    pub vhost_user_video_decoder: Option<VhostUserOption>,
+    pub vhost_user_video_decoder: Vec<VhostUserOption>,
 
     #[argh(option, arg_name = "SOCKET_PATH")]
     #[serde(default)]
@@ -1629,14 +1629,14 @@ pub struct RunCommand {
     #[serde(skip)] // TODO(b/255223604)
     /// (EXPERIMENTAL) enable virtio-video decoder device
     /// Possible backend values: libvda, ffmpeg, vaapi
-    pub video_decoder: Option<VideoDeviceConfig>,
+    pub video_decoder: Vec<VideoDeviceConfig>,
 
     #[cfg(feature = "video-encoder")]
     #[argh(option, arg_name = "[backend]")]
     #[serde(skip)] // TODO(b/255223604)
     /// (EXPERIMENTAL) enable virtio-video encoder device
     /// Possible backend values: libvda
-    pub video_encoder: Option<VideoDeviceConfig>,
+    pub video_encoder: Vec<VideoDeviceConfig>,
 
     #[cfg(feature = "audio")]
     #[argh(

src/crosvm/config.rs

@@ -1306,15 +1306,15 @@ pub struct Config {
     pub vhost_user_mac80211_hwsim: Option<VhostUserOption>,
     pub vhost_user_net: Vec<VhostUserOption>,
     pub vhost_user_snd: Vec<VhostUserOption>,
-    pub vhost_user_video_dec: Option<VhostUserOption>,
+    pub vhost_user_video_dec: Vec<VhostUserOption>,
     pub vhost_user_vsock: Vec<VhostUserOption>,
     pub vhost_user_wl: Option<VhostUserOption>,
     #[cfg(unix)]
     pub vhost_vsock_device: Option<PathBuf>,
     #[cfg(feature = "video-decoder")]
-    pub video_dec: Option<VideoDeviceConfig>,
+    pub video_dec: Vec<VideoDeviceConfig>,
     #[cfg(feature = "video-encoder")]
-    pub video_enc: Option<VideoDeviceConfig>,
+    pub video_enc: Vec<VideoDeviceConfig>,
     pub virtio_input_evdevs: Vec<PathBuf>,
     pub virtio_keyboard: Vec<PathBuf>,
     pub virtio_mice: Vec<PathBuf>,
@@ -1502,7 +1502,7 @@ impl Default for Config {
             vhost_net_device_path: PathBuf::from(VHOST_NET_PATH),
             vhost_user_blk: Vec::new(),
             vhost_user_console: Vec::new(),
-            vhost_user_video_dec: None,
+            vhost_user_video_dec: Vec::new(),
             vhost_user_fs: Vec::new(),
             vhost_user_gpu: Vec::new(),
             vhost_user_mac80211_hwsim: None,
@@ -1513,9 +1513,9 @@ impl Default for Config {
             #[cfg(unix)]
             vhost_vsock_device: None,
             #[cfg(feature = "video-decoder")]
-            video_dec: None,
+            video_dec: Vec::new(),
             #[cfg(feature = "video-encoder")]
-            video_enc: None,
+            video_enc: Vec::new(),
             virtio_input_evdevs: Vec::new(),
             virtio_keyboard: Vec::new(),
             virtio_mice: Vec::new(),

src/crosvm/sys/unix.rs

@@ -237,22 +237,28 @@ fn create_virtio_devices(
     }
 
     #[cfg(feature = "video-decoder")]
-    let video_dec_cfg = if let Some(config) = &cfg.video_dec {
-        let (video_tube, gpu_tube) = Tube::pair().context("failed to create tube")?;
-        resource_bridges.push(gpu_tube);
-        Some((video_tube, config.backend))
-    } else {
-        None
-    };
+    let video_dec_cfg = cfg
+        .video_dec
+        .iter()
+        .map(|config| {
+            let (video_tube, gpu_tube) =
+                Tube::pair().expect("failed to create tube for video decoder");
+            resource_bridges.push(gpu_tube);
+            (video_tube, config.backend)
+        })
+        .collect::<Vec<_>>();
 
     #[cfg(feature = "video-encoder")]
-    let video_enc_cfg = if let Some(config) = &cfg.video_enc {
-        let (video_tube, gpu_tube) = Tube::pair().context("failed to create tube")?;
-        resource_bridges.push(gpu_tube);
-        Some((video_tube, config.backend))
-    } else {
-        None
-    };
+    let video_enc_cfg = cfg
+        .video_enc
+        .iter()
+        .map(|config| {
+            let (video_tube, gpu_tube) =
+                Tube::pair().expect("failed to create tube for video encoder");
+            resource_bridges.push(gpu_tube);
+            (video_tube, config.backend)
+        })
+        .collect::<Vec<_>>();
 
     #[cfg(feature = "gpu")]
     {
@@ -587,18 +593,18 @@ fn create_virtio_devices(
 
     #[cfg(feature = "video-decoder")]
     {
-        if let Some((video_dec_tube, video_dec_backend)) = video_dec_cfg {
+        for (tube, backend) in video_dec_cfg {
             register_video_device(
-                video_dec_backend,
+                backend,
                 &mut devs,
-                video_dec_tube,
+                tube,
                 cfg.protection_type,
                 &cfg.jail_config,
                 VideoDeviceType::Decoder,
             )?;
         }
     }
-    if let Some(socket_path) = &cfg.vhost_user_video_dec {
+    for socket_path in &cfg.vhost_user_video_dec {
         devs.push(create_vhost_user_video_device(
             cfg.protection_type,
             socket_path,
@@ -608,11 +614,11 @@ fn create_virtio_devices(
 
     #[cfg(feature = "video-encoder")]
     {
-        if let Some((video_enc_tube, video_enc_backend)) = video_enc_cfg {
+        for (tube, backend) in video_enc_cfg {
             register_video_device(
-                video_enc_backend,
+                backend,
                 &mut devs,
-                video_enc_tube,
+                tube,
                 cfg.protection_type,
                 &cfg.jail_config,
                 VideoDeviceType::Encoder,