vrend: Prepare for async fence callback support

Once we retire fences directly in the sync thread, we will also need
to check queries in the same loop as virgl_renderer_poll() will no
longer be called.

In order to do that safely, we need to lock around operations on
the query waiting list. We also need to keep track of the current
context for the sync thread given we need to update it before
checking query status.

Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Reviewed-by: Ryan Neph <ryanneph@google.com>

src/vrend_renderer.c

@@ -311,10 +311,14 @@ struct global_renderer_state {
    struct vrend_context *current_ctx;
    struct vrend_context *current_hw_ctx;
 
+   /* fence_mutex should be locked before using the query list
+    * if async fence callback are enabled
+    */
    struct list_head waiting_query_list;
    struct list_head fence_list;
    struct list_head fence_wait_list;
    struct vrend_fence *fence_waiting;
+   struct vrend_context *current_sync_thread_ctx;
 
    int gl_major_ver;
    int gl_minor_ver;
@@ -347,6 +351,8 @@ struct global_renderer_state {
    uint32_t use_explicit_locations : 1;
    /* threaded sync */
    uint32_t stop_sync_thread : 1;
+   /* async fence callback */
+   bool use_async_fence_cb : 1;
    /* Needed on GLES to inject a TCS */
    uint32_t bgra_srgb_emulation_loaded : 1;
 
@@ -5897,6 +5903,18 @@ static GLenum tgsitargettogltarget(const enum pipe_texture_target target, int nr
    return PIPE_BUFFER;
 }
 
+static inline void lock_sync(void)
+{
+   if (vrend_state.sync_thread && vrend_state.use_async_fence_cb)
+      pipe_mutex_lock(vrend_state.fence_mutex);
+}
+
+static inline void unlock_sync(void)
+{
+   if (vrend_state.sync_thread && vrend_state.use_async_fence_cb)
+      pipe_mutex_unlock(vrend_state.fence_mutex);
+}
+
 static void vrend_free_sync_thread(void)
 {
    if (!vrend_state.sync_thread)
@@ -5993,11 +6011,15 @@ static bool do_wait(struct vrend_fence *fence, bool can_block)
    return done;
 }
 
+static void vrend_renderer_check_queries_locked(void);
+
 static void wait_sync(struct vrend_fence *fence)
 {
    do_wait(fence, /* can_block */ true);
 
    pipe_mutex_lock(vrend_state.fence_mutex);
+   if (vrend_state.use_async_fence_cb)
+      vrend_renderer_check_queries_locked();
    list_addtail(&fence->fences, &vrend_state.fence_list);
    vrend_state.fence_waiting = NULL;
    pipe_mutex_unlock(vrend_state.fence_mutex);
@@ -6385,7 +6407,12 @@ static void vrend_destroy_sub_context(struct vrend_sub_context *sub)
    vrend_set_num_vbo_sub(sub, 0);
    vrend_resource_reference((struct vrend_resource **)&sub->ib.buffer, NULL);
 
+   /* need to lock mutex before destroying queries, we could
+    * be checking these in the sync thread */
+   lock_sync();
    vrend_object_fini_ctx_table(sub->object_hash);
+   unlock_sync();
+
    vrend_clicbs->destroy_gl_context(sub->gl_context);
 
    list_del(&sub->head);
@@ -9349,8 +9376,6 @@ int vrend_renderer_create_fence(struct vrend_context *ctx,
    return ENOMEM;
 }
 
-static void vrend_renderer_check_queries(void);
-
 static bool need_fence_retire_signal_locked(struct vrend_fence *fence,
                                             const struct list_head *signaled_list)
 {
@@ -9421,7 +9446,8 @@ void vrend_renderer_check_fences(void)
    if (LIST_IS_EMPTY(&retired_fences))
       return;
 
-   vrend_renderer_check_queries();
+   /* no need to lock when not using a sync thread */
+   vrend_renderer_check_queries_locked();
 
    LIST_FOR_EACH_ENTRY_SAFE(fence, stor, &retired_fences, fences) {
       struct vrend_context *ctx = fence->ctx;
@@ -9465,7 +9491,7 @@ vrend_update_oq_samples_multiplier(struct vrend_context *ctx)
 }
 
 
-static bool vrend_check_query(struct vrend_query *query)
+static bool vrend_check_query_locked(struct vrend_query *query)
 {
    struct virgl_host_query_state state;
    bool ret;
@@ -9496,13 +9522,33 @@ static bool vrend_check_query(struct vrend_query *query)
    return true;
 }
 
-static void vrend_renderer_check_queries(void)
+static bool vrend_hw_switch_query_context(struct vrend_context *ctx)
+{
+   if (vrend_state.use_async_fence_cb) {
+      if (!ctx)
+         return false;
+
+      if (ctx == vrend_state.current_sync_thread_ctx)
+         return true;
+
+      if (ctx->ctx_id != 0 && ctx->in_error)
+         return false;
+
+      vrend_clicbs->make_current(ctx->sub->gl_context);
+      vrend_state.current_sync_thread_ctx = ctx;
+      return true;
+   } else {
+      return vrend_hw_switch_context(ctx, true);
+   }
+}
+
+static void vrend_renderer_check_queries_locked(void)
 {
    struct vrend_query *query, *stor;
 
    LIST_FOR_EACH_ENTRY_SAFE(query, stor, &vrend_state.waiting_query_list, waiting_queries) {
-      if (!vrend_hw_switch_context(query->ctx, true) ||
+      if (!vrend_hw_switch_query_context(query->ctx) ||
-	  vrend_check_query(query))
+	  vrend_check_query_locked(query))
          list_delinit(&query->waiting_queries);
    }
 }
@@ -9673,7 +9719,9 @@ int vrend_begin_query(struct vrend_context *ctx, uint32_t handle)
    if (q->index > 0 && !has_feature(feat_transform_feedback3))
       return EINVAL;
 
+   lock_sync();
    list_delinit(&q->waiting_queries);
+   unlock_sync();
 
    if (q->gltype == GL_TIMESTAMP)
       return 0;
@@ -9724,12 +9772,14 @@ void vrend_get_query_result(struct vrend_context *ctx, uint32_t handle,
    if (!q)
       return;
 
-   ret = vrend_check_query(q);
+   lock_sync();
+   ret = vrend_check_query_locked(q);
    if (ret) {
       list_delinit(&q->waiting_queries);
    } else if (LIST_IS_EMPTY(&q->waiting_queries)) {
       list_addtail(&q->waiting_queries, &vrend_state.waiting_query_list);
    }
+   unlock_sync();
 }
 
 #define COPY_QUERY_RESULT_TO_BUFFER(resid, offset, pvalue, size, multiplier) \