WIP --gpu passthrough support

Experimental and untested

Author: sandorex

src/cli.rs

@@ -130,6 +130,12 @@ pub struct CmdStartArgs {
     #[arg(long, value_name = "BOOL", default_missing_value = "true", require_equals = true, num_args = 0..=1, help_heading = START_HEADING_PERMISSIONS)]
     pub wayland: Option<bool>,
 
+    /// Passes through GPUs by their index, use 0 for all
+    ///
+    /// If passed without argument then use no gpu
+    #[arg(long = "gpus", require_equals = true, num_args = 0.., value_delimiter = ',', help_heading = START_HEADING_PERMISSIONS)]
+    pub gpus: Option<Vec<u8>>,
+
     /// Pass through ssh-agent socket
     #[arg(long, value_name = "BOOL", default_missing_value = "true", require_equals = true, num_args = 0..=1, help_heading = START_HEADING_PERMISSIONS)]
     pub ssh_agent: Option<bool>,

src/commands/cmd_start.rs

@@ -158,6 +158,7 @@ pub fn start_container(ctx: Context, mut cli_args: CmdStartArgs) -> Result<()> {
         cli_args.pipewire = cli_args.pipewire.or(Some(config.pipewire));
         cli_args.pulseaudio = cli_args.pulseaudio.or(Some(config.pulseaudio));
         cli_args.wayland = cli_args.wayland.or(Some(config.wayland));
+        cli_args.gpus = cli_args.gpus.or(Some(config.gpus));
         cli_args.ssh_agent = cli_args.ssh_agent.or(Some(config.ssh_agent));
         cli_args.session_bus = cli_args.session_bus.or(Some(config.session_bus));
         cli_args.ports.extend_from_slice(&config.ports);
@@ -290,6 +291,8 @@ pub fn start_container(ctx: Context, mut cli_args: CmdStartArgs) -> Result<()> {
 
     mount_wayland(&ctx, &cli_args, &mut cmd)?;
 
+    gpu_passthrough(&ctx, &cli_args, &mut cmd)?;
+
     mount_ssh_agent(&ctx, &cli_args, &mut cmd)?;
 
     mount_session_bus(&ctx, &cli_args, &mut cmd)?;

src/commands/cmd_start/util.rs

@@ -224,6 +224,58 @@ pub fn mount_wayland(ctx: &Context, cli_args: &CmdStartArgs, cmd: &mut Command)
     Ok(())
 }
 
+pub fn gpu_passthrough(_ctx: &Context, cli_args: &CmdStartArgs, cmd: &mut Command) -> Result<()> {
+    use std::fs;
+
+    let gpus = cli_args.gpus.clone().unwrap_or_else(|| vec![]);
+
+    // no gpus selected do nothing
+    if gpus.is_empty() {
+        return Ok(());
+    }
+
+    let mut files: Vec<String> = vec![];
+
+    // 0 means copy all
+    if gpus.contains(&0) {
+        log::debug!("Adding all GPU devices");
+
+        for entry in std::fs::read_dir("/dev/dri").expect("Error reading /dev/dri") {
+            let entry = entry?;
+
+            // just filter paths by name
+            let filename = entry.file_name().to_string_lossy().to_string();
+            if filename.starts_with("card") || filename.starts_with("renderD") {
+                log::debug!("Found {:?}", entry.path());
+                files.push(entry.path().to_string_lossy().to_string());
+            }
+        }
+    } else {
+        log::debug!("Adding GPU devices");
+
+        for gpu_index in gpus {
+            // NOTE: for some reason first card is /dev/dri/card1 and /dev/renderD128
+            let card = format!("/dev/dri/card{gpu_index}");
+            let render = format!("/dev/dri/renderD{}", 127 + gpu_index);
+
+            if fs::exists(&card).is_ok_and(|x| x) && fs::exists(&render).is_ok_and(|x| x) {
+                log::debug!("Found GPU {gpu_index} at {card:?} and {render:?}");
+
+                files.push(card);
+                files.push(render);
+            } else {
+                return Err(anyhow!("Could not find card with index {gpu_index}"));
+            }
+        }
+    }
+
+    for path in files {
+        cmd.args([format!("--device={path}")]);
+    }
+
+    Ok(())
+}
+
 pub fn mount_additional_mounts(
     ws_dir: &Path,
     cli_args: &CmdStartArgs,

src/config/v1.rs

@@ -51,6 +51,10 @@ code_docs_struct! {
         #[serde(default)]
         pub wayland: bool,
 
+        /// Passthrough GPUs by their index, use 0 for all
+        #[serde(default)]
+        pub gpus: Vec<u8>,
+
         /// Passthrough ssh-agent socket, security impact is unknown
         #[serde(default)]
         pub ssh_agent: bool,