Add CLI flag --gpu=drm|venus|software to support various GPU virtualization modes

crates/muvm/src/bin/muvm.rs

@@ -11,7 +11,8 @@ use krun_sys::{
     krun_add_disk, krun_add_virtiofs2, krun_add_vsock_port, krun_add_vsock_port2, krun_create_ctx,
     krun_set_env, krun_set_gpu_options2, krun_set_log_level, krun_set_passt_fd, krun_set_root,
     krun_set_vm_config, krun_set_workdir, krun_start_enter, VIRGLRENDERER_DRM,
-    VIRGLRENDERER_THREAD_SYNC, VIRGLRENDERER_USE_ASYNC_FENCE_CB, VIRGLRENDERER_USE_EGL,
+    VIRGLRENDERER_NO_VIRGL, VIRGLRENDERER_RENDER_SERVER, VIRGLRENDERER_THREAD_SYNC,
+    VIRGLRENDERER_USE_ASYNC_FENCE_CB, VIRGLRENDERER_USE_EGL, VIRGLRENDERER_VENUS,
 };
 use log::debug;
 use muvm::cli_options::options;
@@ -184,8 +185,14 @@ fn main() -> Result<ExitCode> {
                 .context("Failed to configure the number of vCPUs and/or the amount of RAM");
         }
 
+        let virgl_mode = match options.gpu_mode.unwrap_or_default() {
+            muvm::cli_options::GpuMode::Drm => VIRGLRENDERER_DRM,
+            muvm::cli_options::GpuMode::Venus => VIRGLRENDERER_VENUS | VIRGLRENDERER_RENDER_SERVER,
+            muvm::cli_options::GpuMode::Software => 0,
+        };
         let virgl_flags = VIRGLRENDERER_USE_EGL
-            | VIRGLRENDERER_DRM
+            | VIRGLRENDERER_NO_VIRGL /* Legacy method that we don't support; interferes with software-only mode */
+            | virgl_mode
             | VIRGLRENDERER_THREAD_SYNC
             | VIRGLRENDERER_USE_ASYNC_FENCE_CB;
         // SAFETY: Safe as no pointers involved.
@@ -436,6 +443,10 @@ fn main() -> Result<ExitCode> {
         env.insert("XAUTHORITY".to_owned(), xauthority);
     }
 
+    if options.gpu_mode == Some(muvm::cli_options::GpuMode::Venus) {
+        env.insert("MESA_LOADER_DRIVER_OVERRIDE".to_owned(), "zink".to_owned());
+    }
+
     let krun_config = KrunBaseConfig {
         config: KrunConfig {
             args: muvm_guest_args,

crates/muvm/src/cli_options.rs

@@ -7,6 +7,29 @@ use bpaf::{any, construct, long, positional, OptionParser, Parser};
 use crate::types::MiB;
 use crate::utils::launch::Emulator;
 
+#[derive(Debug, Clone, Copy, Default, PartialEq)]
+pub enum GpuMode {
+    #[default]
+    Drm,
+    Venus,
+    Software,
+}
+
+impl std::str::FromStr for GpuMode {
+    type Err = String;
+    fn from_str(s: &str) -> Result<Self, String>
+    where
+        Self: Sized,
+    {
+        match s {
+            "drm" => Ok(GpuMode::Drm),
+            "venus" => Ok(GpuMode::Venus),
+            "software" => Ok(GpuMode::Software),
+            x => Err(format!("Expected drm|venus|software, got '{x}'")),
+        }
+    }
+}
+
 #[derive(Clone, Debug)]
 pub struct Options {
     pub cpu_list: Vec<Range<u16>>,
@@ -19,6 +42,7 @@ pub struct Options {
     pub interactive: bool,
     pub tty: bool,
     pub privileged: bool,
+    pub gpu_mode: Option<GpuMode>,
     pub publish_ports: Vec<String>,
     pub emulator: Option<Emulator>,
     pub init_commands: Vec<PathBuf>,
@@ -125,6 +149,10 @@ pub fn options() -> OptionParser<Options> {
         This notably does not allow root access to the host fs.",
         )
         .switch();
+    let gpu_mode = long("gpu-mode")
+        .help("Use the given GPU virtualization method")
+        .argument::<GpuMode>("drm|venus|software")
+        .optional();
     let publish_ports = long("publish")
         .short('p')
         .help(
@@ -169,6 +197,7 @@ pub fn options() -> OptionParser<Options> {
         interactive,
         tty,
         privileged,
+        gpu_mode,
         publish_ports,
         emulator,
         init_commands,