[PATCH 01/19] drm/i915: don't do allocate_va_range again on pin update

[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 that 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>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
 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 ac2b8f64c770..c8dd8835ed8e 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_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