rutabaga_gfx: enable per-context/per-ring fencing for virgl_renderer

Permits virglrenderer contexts to make use of per-context/per-ring
fencing.

BUG=b:193892617
TEST=Run glxgears and vkcube in a crosvm guest VM.

Change-Id: I9800d3fbab788602a25f2a118619910300126d4b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3453115
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Ryan Neph <ryanneph@google.com>

rutabaga_gfx/src/rutabaga_core.rs

@@ -187,7 +187,7 @@ pub trait RutabagaContext {
     fn detach(&mut self, _resource: &RutabagaResource);
 
     /// Implementations must create a fence on specified `ring_idx` in `fence`.  This
-    /// allows for multiple syncrhonizations timelines per RutabagaContext.
+    /// allows for multiple synchronizations timelines per RutabagaContext.
     fn context_create_fence(&mut self, _fence: RutabagaFence) -> RutabagaResult<()> {
         Err(RutabagaError::Unsupported)
     }

rutabaga_gfx/src/virgl_renderer.rs

@@ -12,6 +12,8 @@ use std::convert::TryFrom;
 use std::mem::{size_of, transmute};
 use std::os::raw::{c_char, c_void};
 use std::os::unix::io::AsRawFd;
+use std::panic::catch_unwind;
+use std::process::abort;
 use std::ptr::null_mut;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
@@ -75,6 +77,18 @@ impl RutabagaContext for VirglRendererContext {
     fn component_type(&self) -> RutabagaComponentType {
         RutabagaComponentType::VirglRenderer
     }
+
+    fn context_create_fence(&mut self, fence: RutabagaFence) -> RutabagaResult<()> {
+        let ret = unsafe {
+            virgl_renderer_context_create_fence(
+                fence.ctx_id,
+                fence.flags,
+                fence.ring_idx as u64,
+                fence.fence_id as *mut ::std::os::raw::c_void,
+            )
+        };
+        ret_to_res(ret)
+    }
 }
 
 impl Drop for VirglRendererContext {
@@ -113,6 +127,35 @@ extern "C" fn debug_callback(fmt: *const ::std::os::raw::c_char, ap: stdio::va_l
     }
 }
 
+/// Virglrenderer's vtest renderer currently expects an opaque "void *fence_cookie" rather than a
+/// bare "u64 fence_id", so we cannot use the common implementation from renderer_utils yet.
+///
+/// TODO(ryanneph): re-evaluate if vtest can be modified so this can be unified with
+/// write_context_fence() from renderer_utils before promoting to cfg(feature = "virgl_renderer").
+#[cfg(feature = "virgl_renderer_next")]
+extern "C" fn write_context_fence(
+    cookie: *mut c_void,
+    ctx_id: u32,
+    ring_idx: u64,
+    fence_cookie: *mut c_void,
+) {
+    catch_unwind(|| {
+        assert!(!cookie.is_null());
+        let cookie = unsafe { &*(cookie as *mut VirglCookie) };
+
+        // Call fence completion callback
+        if let Some(handler) = &cookie.fence_handler {
+            handler.call(RutabagaFence {
+                flags: RUTABAGA_FLAG_FENCE | RUTABAGA_FLAG_INFO_RING_IDX,
+                fence_id: fence_cookie as u64,
+                ctx_id,
+                ring_idx: ring_idx as u8,
+            });
+        }
+    })
+    .unwrap_or_else(|_| abort())
+}
+
 const VIRGL_RENDERER_CALLBACKS: &virgl_renderer_callbacks = &virgl_renderer_callbacks {
     #[cfg(not(feature = "virgl_renderer_next"))]
     version: 1,
@@ -123,7 +166,10 @@ const VIRGL_RENDERER_CALLBACKS: &virgl_renderer_callbacks = &virgl_renderer_call
     destroy_gl_context: None,
     make_current: None,
     get_drm_fd: None,
+    #[cfg(not(feature = "virgl_renderer_next"))]
     write_context_fence: None,
+    #[cfg(feature = "virgl_renderer_next")]
+    write_context_fence: Some(write_context_fence),
     #[cfg(not(feature = "virgl_renderer_next"))]
     get_server_fd: None,
     #[cfg(feature = "virgl_renderer_next")]