drm/i915: Make engine's batch pool safe for use with virtual engines

A virtual engine itself does not have a batch pool, but we can gleefully
use any of its siblings instead.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190827135935.3831-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c

@@ -1145,7 +1145,7 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
 	u32 *cmd;
 	int err;
 
-	pool = intel_engine_pool_get(&eb->engine->pool, PAGE_SIZE);
+	pool = intel_engine_get_pool(eb->engine, PAGE_SIZE);
 	if (IS_ERR(pool))
 		return PTR_ERR(pool);
 
@@ -1963,7 +1963,7 @@ static struct i915_vma *eb_parse(struct i915_execbuffer *eb, bool is_master)
 	struct i915_vma *vma;
 	int err;
 
-	pool = intel_engine_pool_get(&eb->engine->pool, eb->batch_len);
+	pool = intel_engine_get_pool(eb->engine, eb->batch_len);
 	if (IS_ERR(pool))
 		return ERR_CAST(pool);
 

drivers/gpu/drm/i915/gem/i915_gem_object_blt.c

@@ -32,7 +32,7 @@ struct i915_vma *intel_emit_vma_fill_blt(struct intel_context *ce,
 	count = div_u64(vma->size, block_size);
 	size = (1 + 8 * count) * sizeof(u32);
 	size = round_up(size, PAGE_SIZE);
-	pool = intel_engine_pool_get(&ce->engine->pool, size);
+	pool = intel_engine_get_pool(ce->engine, size);
 	if (IS_ERR(pool)) {
 		err = PTR_ERR(pool);
 		goto out_pm;
@@ -216,7 +216,7 @@ struct i915_vma *intel_emit_vma_copy_blt(struct intel_context *ce,
 	count = div_u64(dst->size, block_size);
 	size = (1 + 11 * count) * sizeof(u32);
 	size = round_up(size, PAGE_SIZE);
-	pool = intel_engine_pool_get(&ce->engine->pool, size);
+	pool = intel_engine_get_pool(ce->engine, size);
 	if (IS_ERR(pool)) {
 		err = PTR_ERR(pool);
 		goto out_pm;

drivers/gpu/drm/i915/gt/intel_engine_pool.c

@@ -107,9 +107,19 @@ node_create(struct intel_engine_pool *pool, size_t sz)
 	return node;
 }
 
-struct intel_engine_pool_node *
-intel_engine_pool_get(struct intel_engine_pool *pool, size_t size)
+static struct intel_engine_pool *lookup_pool(struct intel_engine_cs *engine)
 {
+	if (intel_engine_is_virtual(engine))
+		engine = intel_virtual_engine_get_sibling(engine, 0);
+
+	GEM_BUG_ON(!engine);
+	return &engine->pool;
+}
+
+struct intel_engine_pool_node *
+intel_engine_get_pool(struct intel_engine_cs *engine, size_t size)
+{
+	struct intel_engine_pool *pool = lookup_pool(engine);
 	struct intel_engine_pool_node *node;
 	struct list_head *list;
 	unsigned long flags;

drivers/gpu/drm/i915/gt/intel_engine_pool.h

@@ -12,7 +12,7 @@
 #include "i915_request.h"
 
 struct intel_engine_pool_node *
-intel_engine_pool_get(struct intel_engine_pool *pool, size_t size);
+intel_engine_get_pool(struct intel_engine_cs *engine, size_t size);
 
 static inline int
 intel_engine_pool_mark_active(struct intel_engine_pool_node *node,

drivers/gpu/drm/i915/gt/intel_lrc.c

@@ -3851,6 +3851,18 @@ int intel_virtual_engine_attach_bond(struct intel_engine_cs *engine,
 	return 0;
 }
 
+struct intel_engine_cs *
+intel_virtual_engine_get_sibling(struct intel_engine_cs *engine,
+				 unsigned int sibling)
+{
+	struct virtual_engine *ve = to_virtual_engine(engine);
+
+	if (sibling >= ve->num_siblings)
+		return NULL;
+
+	return ve->siblings[sibling];
+}
+
 void intel_execlists_show_requests(struct intel_engine_cs *engine,
 				   struct drm_printer *m,
 				   void (*show_request)(struct drm_printer *m,

drivers/gpu/drm/i915/gt/intel_lrc.h

@@ -131,4 +131,8 @@ int intel_virtual_engine_attach_bond(struct intel_engine_cs *engine,
 				     const struct intel_engine_cs *master,
 				     const struct intel_engine_cs *sibling);
 
+struct intel_engine_cs *
+intel_virtual_engine_get_sibling(struct intel_engine_cs *engine,
+				 unsigned int sibling);
+
 #endif /* _INTEL_LRC_H_ */