[PATCH 05/17] drm/i915: don't call allocate_range_va_range when already bound

[Matthew Auld]

If a vma is already bound to a ppgtt, we incorrectly call
allocate_va_range again when doing a pin update, which will result in
over accounting within our paging structures, such when we do unbind
something we don't actually destroy the structures and end up
inadvertently recycling them. In reality this probably isn't too bad,
but once we start touching PDEs and PDPEs for 64K/2M/1G pages this
apparent recycling will manifest into lots of really, really subtle
bugs.

Fixes: ff685975d97f ("drm/i915: Move allocate_va_range to GTT")
Signed-off-by: Matthew Auld <matthew.auld at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 8bab4aea63e6..ae89647e9fed 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -191,11 +191,15 @@ static int ppgtt_bind_vma(struct i915_vma *vma,
 			  u32 unused)
 {
 	u32 pte_flags;
+	u32 vma_flags = vma->flags & (I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND);
 	int ret;
 
-	ret = vma->vm->allocate_va_range(vma->vm, vma->node.start, vma->size);
-	if (ret)
-		return ret;
+	if (vma_flags == 0) {
+		ret = vma->vm->allocate_va_range(vma->vm, vma->node.start,
+						 vma->size);
+		if (ret)
+			return ret;
+	}
 
 	vma->pages = vma->obj->mm.pages;
 
@@ -2288,6 +2292,7 @@ static int aliasing_gtt_bind_vma(struct i915_vma *vma,
 {
 	struct drm_i915_private *i915 = vma->vm->i915;
 	u32 pte_flags;
+	u32 vma_flags = vma->flags & (I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND);
 	int ret;
 
 	if (unlikely(!vma->pages)) {
@@ -2304,7 +2309,7 @@ static int aliasing_gtt_bind_vma(struct i915_vma *vma,
 	if (flags & I915_VMA_LOCAL_BIND) {
 		struct i915_hw_ppgtt *appgtt = i915->mm.aliasing_ppgtt;
 
-		if (appgtt->base.allocate_va_range) {
+		if (vma_flags == 0 && appgtt->base.allocate_va_range) {
 			ret = appgtt->base.allocate_va_range(&appgtt->base,
 							     vma->node.start,
 							     vma->node.size);
@@ -2328,7 +2333,7 @@ static int aliasing_gtt_bind_vma(struct i915_vma *vma,
 	return 0;
 
 err_pages:
-	if (!(vma->flags & (I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND))) {
+	if (vma_flags == 0) {
 		if (vma->pages != vma->obj->mm.pages) {
 			GEM_BUG_ON(!vma->pages);
 			sg_free_table(vma->pages);
-- 
2.9.3