drm/i915/gtt: Allocate va range only if vma is not bound

When we have bound vma into an address space, the layout
of page table structures is immutable. So we can be absolutely
certain that if vma is already bound, there is no need to
(re)allocate a virtual address range for it.

v2: - add sanity checks and remove superfluous GLOBAL_BIND set
    - we might do update for an unbound vma (Chris)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90224
Testcase: igt/gem_exec_big #bdw
Reported-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michel Thierry <michel.thierry@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -1928,8 +1928,6 @@ static int ggtt_bind_vma(struct i915_vma *vma,
 		vma->vm->insert_entries(vma->vm, pages,
 					vma->node.start,
 					cache_level, pte_flags);
-
-		vma->bound |= GLOBAL_BIND;
 	}
 
 	if (dev_priv->mm.aliasing_ppgtt && flags & LOCAL_BIND) {
@@ -2804,21 +2802,13 @@ i915_get_ggtt_vma_pages(struct i915_vma *vma)
 int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level,
 		  u32 flags)
 {
-	int ret = 0;
-	u32 bind_flags = 0;
-
-	if (vma->vm->allocate_va_range) {
-		trace_i915_va_alloc(vma->vm, vma->node.start,
-				    vma->node.size,
-				    VM_TO_TRACE_NAME(vma->vm));
+	int ret;
+	u32 bind_flags;
 
-		ret = vma->vm->allocate_va_range(vma->vm,
-						 vma->node.start,
-						 vma->node.size);
-		if (ret)
-			return ret;
-	}
+	if (WARN_ON(flags == 0))
+		return -EINVAL;
 
+	bind_flags = 0;
 	if (flags & PIN_GLOBAL)
 		bind_flags |= GLOBAL_BIND;
 	if (flags & PIN_USER)
@@ -2829,8 +2819,23 @@ int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level,
 	else
 		bind_flags &= ~vma->bound;
 
-	if (bind_flags)
-		ret = vma->vm->bind_vma(vma, cache_level, bind_flags);
+	if (bind_flags == 0)
+		return 0;
+
+	if (vma->bound == 0 && vma->vm->allocate_va_range) {
+		trace_i915_va_alloc(vma->vm,
+				    vma->node.start,
+				    vma->node.size,
+				    VM_TO_TRACE_NAME(vma->vm));
+
+		ret = vma->vm->allocate_va_range(vma->vm,
+						 vma->node.start,
+						 vma->node.size);
+		if (ret)
+			return ret;
+	}
+
+	ret = vma->vm->bind_vma(vma, cache_level, bind_flags);
 	if (ret)
 		return ret;