virgl: add support for per-context fencing

Per-context fences signal in creation order only within a context.  Two
per-context fences in two contexts might signal in any order.

When a per-context fence is created, a fence cookie can be specified.
The cookie will be passed to write_context_fence callback.  This
replaces fence_id that is used in ctx0 fencing.

write_context_fence is called on each fence unless the fence has
VIRGL_RENDERER_FENCE_FLAG_MERGEABLE set.  When the bit is set,
write_context_fence might be skipped.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Acked-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>

src/virglrenderer.c

@@ -165,10 +165,14 @@ void virgl_renderer_fill_caps(uint32_t set, uint32_t version,
    }
 }
 
-static void per_context_fence_retire(UNUSED struct virgl_context *ctx,
+static void per_context_fence_retire(struct virgl_context *ctx,
-                                     UNUSED uint64_t queue_id,
+                                     uint64_t queue_id,
-                                     UNUSED void *fence_cookie)
+                                     void *fence_cookie)
 {
+   state.cbs->write_context_fence(state.cookie,
+                                  ctx->ctx_id,
+                                  queue_id,
+                                  fence_cookie);
 }
 
 int virgl_renderer_context_create_with_flags(uint32_t ctx_id,
@@ -363,6 +367,37 @@ int virgl_renderer_create_fence(int client_fence_id, UNUSED uint32_t ctx_id)
    return EINVAL;
 }
 
+int virgl_renderer_context_create_fence(uint32_t ctx_id,
+                                        uint32_t flags,
+                                        uint64_t queue_id,
+                                        void *fence_cookie)
+{
+   struct virgl_context *ctx = virgl_context_lookup(ctx_id);
+   if (!ctx)
+      return -EINVAL;
+
+   assert(state.cbs->version >= 3 && state.cbs->write_context_fence);
+   return ctx->submit_fence(ctx, flags, queue_id, fence_cookie);
+}
+
+void virgl_renderer_context_poll(uint32_t ctx_id)
+{
+   struct virgl_context *ctx = virgl_context_lookup(ctx_id);
+   if (!ctx)
+      return;
+
+   ctx->retire_fences(ctx);
+}
+
+int virgl_renderer_context_get_poll_fd(uint32_t ctx_id)
+{
+   struct virgl_context *ctx = virgl_context_lookup(ctx_id);
+   if (!ctx)
+      return -1;
+
+   return ctx->get_fencing_fd(ctx);
+}
+
 void virgl_renderer_force_ctx_0(void)
 {
    TRACE_FUNC();

src/virglrenderer.h

@@ -45,7 +45,11 @@ struct virgl_renderer_gl_ctx_param {
    int minor_ver;
 };
 
+#ifdef VIRGL_RENDERER_UNSTABLE_APIS
+#define VIRGL_RENDERER_CALLBACKS_VERSION 3
+#else
 #define VIRGL_RENDERER_CALLBACKS_VERSION 2
+#endif
 
 struct virgl_renderer_callbacks {
    int version;
@@ -57,6 +61,10 @@ struct virgl_renderer_callbacks {
    int (*make_current)(void *cookie, int scanout_idx, virgl_renderer_gl_context ctx);
 
    int (*get_drm_fd)(void *cookie); /* v2, used with flags & VIRGL_RENDERER_USE_EGL */
+
+#ifdef VIRGL_RENDERER_UNSTABLE_APIS
+   void (*write_context_fence)(void *cookie, uint32_t ctx_id, uint64_t queue_id, void *fence_cookie);
+#endif
 };
 
 /* virtio-gpu compatible interface */
@@ -307,6 +315,14 @@ virgl_renderer_resource_export_blob(uint32_t res_id, uint32_t *fd_type, int *fd)
 VIRGL_EXPORT int
 virgl_renderer_export_fence(uint32_t client_fence_id, int *fd);
 
+#define VIRGL_RENDERER_FENCE_FLAG_MERGEABLE      (1 << 0)
+VIRGL_EXPORT int virgl_renderer_context_create_fence(uint32_t ctx_id,
+                                                     uint32_t flags,
+                                                     uint64_t queue_id,
+                                                     void *fence_cookie);
+VIRGL_EXPORT void virgl_renderer_context_poll(uint32_t ctx_id); /* force fences */
+VIRGL_EXPORT int virgl_renderer_context_get_poll_fd(uint32_t ctx_id);
+
 #endif /* VIRGL_RENDERER_UNSTABLE_APIS */
 
 #endif

src/vrend_renderer.c

@@ -9234,6 +9234,10 @@ static bool need_fence_retire_signal_locked(struct vrend_fence *fence)
    if (next->ctx != fence->ctx)
       return true;
 
+   /* not mergeable */
+   if (!(fence->flags & VIRGL_RENDERER_FENCE_FLAG_MERGEABLE))
+      return true;
+
    return false;
 }
 
@@ -11018,7 +11022,8 @@ int vrend_renderer_resource_unmap(struct pipe_resource *pres)
 int vrend_renderer_create_ctx0_fence(uint32_t fence_id)
 {
    void *fence_cookie = (void *)(uintptr_t)fence_id;
-   return vrend_renderer_create_fence(vrend_state.ctx0, 0, fence_cookie);
+   return vrend_renderer_create_fence(vrend_state.ctx0,
+         VIRGL_RENDERER_FENCE_FLAG_MERGEABLE, fence_cookie);
 }
 
 static bool find_ctx0_fence_locked(struct list_head *fence_list,