libkrun: Refactor VirtioFsTable to VirtioFsLookup trait

src/cross_domain/atomic_memory_sentinel_manager.rs

@@ -19,10 +19,8 @@ use mesa3d_util::AtomicMemorySentinel;
 use mesa3d_util::Event;
 use mesa3d_util::MemoryMapping;
 use mesa3d_util::MesaError;
-use mesa3d_util::OwnedDescriptor;
 
-use crate::rutabaga_core::VirtioFsKey;
-use crate::rutabaga_core::VirtioFsTable;
+use crate::rutabaga_core::VirtioFsLookup;
 use crate::rutabaga_utils::RutabagaError;
 use crate::rutabaga_utils::RutabagaResult;
 use crate::rutabaga_utils::RUTABAGA_MAP_ACCESS_RW;
@@ -125,15 +123,15 @@ impl Drop for SentinelInstance {
 /// Manager for all atomic memory sentinel watchers
 pub struct AtomicMemorySentinelManager {
     watchers: Map<u32, SentinelInstance>,
-    virtiofs_table: Option<VirtioFsTable>,
+    virtiofs_lookup: Option<Arc<dyn VirtioFsLookup>>,
 }
 
 impl AtomicMemorySentinelManager {
     /// Creates a new AtomicMemorySentinelManager
-    pub fn new(virtiofs_table: Option<VirtioFsTable>) -> Self {
+    pub fn new(virtiofs_lookup: Option<Arc<dyn VirtioFsLookup>>) -> Self {
         Self {
             watchers: Map::new(),
-            virtiofs_table,
+            virtiofs_lookup,
         }
     }
 
@@ -143,20 +141,12 @@ impl AtomicMemorySentinelManager {
             return Err(RutabagaError::AlreadyInUse);
         }
 
-        let virtiofs_table = self
-            .virtiofs_table
+        let virtiofs_lookup = self
+            .virtiofs_lookup
             .as_ref()
             .ok_or(RutabagaError::InvalidCrossDomainItemId)?;
-        let virtiofs = virtiofs_table.lock().unwrap();
 
-        let key = VirtioFsKey { fs_id, handle };
-        let file = virtiofs
-            .get(&key)
-            .ok_or(RutabagaError::InvalidCrossDomainItemId)?
-            .try_clone()
-            .map_err(MesaError::IoError)?;
-
-        let handle = OwnedDescriptor::from(file);
+        let handle = virtiofs_lookup.get_exported_descriptor(fs_id, handle)?;
         let mapping = MemoryMapping::from_safe_descriptor(
             handle,
             size_of::<u32>(),

src/cross_domain/mod.rs

@@ -44,7 +44,7 @@ use crate::handle::RutabagaHandle;
 use crate::rutabaga_core::RutabagaComponent;
 use crate::rutabaga_core::RutabagaContext;
 use crate::rutabaga_core::RutabagaResource;
-use crate::rutabaga_core::VirtioFsTable;
+use crate::rutabaga_core::VirtioFsLookup;
 use crate::rutabaga_utils::Resource3DInfo;
 use crate::rutabaga_utils::ResourceCreateBlob;
 use crate::rutabaga_utils::RutabagaComponentType;
@@ -146,7 +146,7 @@ pub struct CrossDomain {
     paths: Option<Vec<RutabagaPath>>,
     gralloc: Arc<Mutex<RutabagaGralloc>>,
     fence_handler: RutabagaFenceHandler,
-    virtiofs_table: Option<VirtioFsTable>,
+    virtiofs_lookup: Option<Arc<dyn VirtioFsLookup>>,
 }
 
 // TODO(gurchetansingh): optimize the item tracker.  Each requirements blob is long-lived and can
@@ -587,14 +587,14 @@ impl CrossDomain {
     pub fn init(
         paths: Option<Vec<RutabagaPath>>,
         fence_handler: RutabagaFenceHandler,
-        virtiofs_table: Option<VirtioFsTable>,
+        virtiofs_lookup: Option<Arc<dyn VirtioFsLookup>>,
     ) -> RutabagaResult<Box<dyn RutabagaComponent>> {
         let gralloc = RutabagaGralloc::new(RutabagaGrallocBackendFlags::new())?;
         Ok(Box::new(CrossDomain {
             paths,
             gralloc: Arc::new(Mutex::new(gralloc)),
             fence_handler,
-            virtiofs_table,
+            virtiofs_lookup,
         }))
     }
 }
@@ -1280,7 +1280,7 @@ impl RutabagaComponent for CrossDomain {
             context_resources: Arc::new(Mutex::new(Default::default())),
             item_state: Arc::new(Mutex::new(Default::default())),
             sentinel_manager: Arc::new(Mutex::new(AtomicMemorySentinelManager::new(
-                self.virtiofs_table.clone(),
+                self.virtiofs_lookup.clone(),
             ))),
             fence_handler,
             worker_thread: None,

src/lib.rs

@@ -38,6 +38,7 @@ pub use crate::rutabaga_core::calculate_capset_mask;
 pub use crate::rutabaga_core::calculate_capset_names;
 pub use crate::rutabaga_core::Rutabaga;
 pub use crate::rutabaga_core::RutabagaBuilder;
+pub use crate::rutabaga_core::VirtioFsLookup;
 pub use crate::rutabaga_gralloc::DrmFormat;
 pub use crate::rutabaga_gralloc::ImageAllocationInfo;
 pub use crate::rutabaga_gralloc::ImageMemoryRequirements;

src/rutabaga_core.rs

@@ -5,11 +5,10 @@
 //! rutabaga_core: Cross-platform, Rust-based, Wayland and Vulkan centric GPU virtualization.
 use std::collections::BTreeMap as Map;
 use std::convert::TryInto;
-use std::fs::File;
 use std::io::IoSlice;
 use std::io::IoSliceMut;
 use std::path::Path;
-use std::sync::{Arc, Mutex};
+use std::sync::Arc;
 
 use mesa3d_util::MemoryMapping;
 use mesa3d_util::MesaError;
@@ -64,17 +63,15 @@ use crate::snapshot::RutabagaSnapshotWriter;
 use crate::virgl_renderer::VirglRenderer;
 use crate::RutabagaPaths;
 
-/// Key for identifying a file in the VirtioFS table.
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
-pub struct VirtioFsKey {
-    /// VirtioFS filesystem ID (identifies which virtio-fs instance)
-    pub fs_id: u64,
-    /// File handle within the filesystem (identifies a specific file)
-    pub handle: u64,
+/// Trait for looking up exported file descriptors from virtio-fs.
+///
+/// Allows VMMs to use different data structures and concurrency strategies.
+/// The trait can be extended in the future to support inode-based lookups for O_PATH fds.
+pub trait VirtioFsLookup: Send + Sync {
+    /// Retrieves an exported file descriptor by filesystem ID and handle.
+    fn get_exported_descriptor(&self, fs_id: u64, handle: u64) -> RutabagaResult<OwnedDescriptor>;
 }
 
-pub type VirtioFsTable = Arc<Mutex<Map<VirtioFsKey, File>>>;
-
 const RUTABAGA_DEFAULT_WIDTH: u32 = 1280;
 const RUTABAGA_DEFAULT_HEIGHT: u32 = 1024;
 
@@ -1301,7 +1298,7 @@ pub struct RutabagaBuilder {
     debug_handler: Option<RutabagaDebugHandler>,
     renderer_features: Option<String>,
     server_descriptor: Option<OwnedDescriptor>,
-    virtiofs_table: Option<VirtioFsTable>,
+    virtiofs_lookup: Option<Arc<dyn VirtioFsLookup>>,
 }
 
 impl RutabagaBuilder {
@@ -1323,7 +1320,7 @@ impl RutabagaBuilder {
             debug_handler: None,
             renderer_features: None,
             server_descriptor: None,
-            virtiofs_table: None,
+            virtiofs_lookup: None,
         }
     }
 
@@ -1428,9 +1425,12 @@ impl RutabagaBuilder {
         self
     }
 
-    /// Set export table for the RutabagaBuilder
-    pub fn set_export_table(mut self, virtiofs_table: VirtioFsTable) -> RutabagaBuilder {
-        self.virtiofs_table = Some(virtiofs_table);
+    /// Set VirtioFS lookup implementation for the RutabagaBuilder
+    pub fn set_virtiofs_lookup(
+        mut self,
+        virtiofs_lookup: Arc<dyn VirtioFsLookup>,
+    ) -> RutabagaBuilder {
+        self.virtiofs_lookup = Some(virtiofs_lookup);
         self
     }
 
@@ -1551,7 +1551,7 @@ impl RutabagaBuilder {
             let cross_domain = CrossDomain::init(
                 self.paths.clone(),
                 self.fence_handler.clone(),
-                self.virtiofs_table.clone(),
+                self.virtiofs_lookup.clone(),
             )?;
             rutabaga_components.insert(RutabagaComponentType::CrossDomain, cross_domain);
             push_capset(RUTABAGA_CAPSET_CROSS_DOMAIN);

src/rutabaga_utils.rs

@@ -651,7 +651,6 @@ pub const RUTABAGA_HANDLE_TYPE_PLATFORM_SCREEN_BUFFER_QNX: u32 = 0x01000000;
 pub const RUTABAGA_HANDLE_TYPE_PLATFORM_EGL_NATIVE_PIXMAP: u32 = 0x02000000;
 pub const RUTABAGA_HANDLE_TYPE_PLATFORM_AHB: u32 = 0x03000000;
 
-
 #[derive(Clone)]
 pub struct RutabagaHandler<S> {
     closure: Arc<dyn Fn(S) + Send + Sync>,