drm/i915/lmem: Verify checks for lmem residency

Since objects can be migrated or evicted when not pinned or locked,
update the checks for lmem residency or future residency so that
the value returned is not immediately stale.

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210610070152.572423-3-thomas.hellstrom@linux.intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 362bff9beb5ce28d44b1fccd87adef1852e05696..6be1b31af07b83763dac4e7f32ee033c21515acb 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -11771,7 +11771,7 @@ intel_user_framebuffer_create(struct drm_device *dev,
 
        /* object is backed with LMEM for discrete */
        i915 = to_i915(obj->base.dev);
-       if (HAS_LMEM(i915) && !i915_gem_object_is_lmem(obj)) {
+       if (HAS_LMEM(i915) && !i915_gem_object_validates_to_lmem(obj)) {
                /* object is "remote", not in local memory */
                i915_gem_object_put(obj);
                return ERR_PTR(-EREMOTE);

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_lmem.c b/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
index 2b8cd15de1d961a6018a53d3bcaa64f5600b0f8e..d539dffa15547958963bc2a4c501f753d155cec8 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
@@ -23,10 +23,50 @@ i915_gem_object_lmem_io_map(struct drm_i915_gem_object *obj,
        return io_mapping_map_wc(&obj->mm.region->iomap, offset, size);
 }
 
+/**
+ * i915_gem_object_validates_to_lmem - Whether the object is resident in
+ * lmem when pages are present.
+ * @obj: The object to check.
+ *
+ * Migratable objects residency may change from under us if the object is
+ * not pinned or locked. This function is intended to be used to check whether
+ * the object can only reside in lmem when pages are present.
+ *
+ * Return: Whether the object is always resident in lmem when pages are
+ * present.
+ */
+bool i915_gem_object_validates_to_lmem(struct drm_i915_gem_object *obj)
+{
+       struct intel_memory_region *mr = READ_ONCE(obj->mm.region);
+
+       return !i915_gem_object_migratable(obj) &&
+               mr && (mr->type == INTEL_MEMORY_LOCAL ||
+                      mr->type == INTEL_MEMORY_STOLEN_LOCAL);
+}
+
+/**
+ * i915_gem_object_is_lmem - Whether the object is resident in
+ * lmem
+ * @obj: The object to check.
+ *
+ * Even if an object is allowed to migrate and change memory region,
+ * this function checks whether it will always be present in lmem when
+ * valid *or* if that's not the case, whether it's currently resident in lmem.
+ * For migratable and evictable objects, the latter only makes sense when
+ * the object is locked.
+ *
+ * Return: Whether the object migratable but resident in lmem, or not
+ * migratable and will be present in lmem when valid.
+ */
 bool i915_gem_object_is_lmem(struct drm_i915_gem_object *obj)
 {
-       struct intel_memory_region *mr = obj->mm.region;
+       struct intel_memory_region *mr = READ_ONCE(obj->mm.region);
 
+#ifdef CONFIG_LOCKDEP
+       if (i915_gem_object_migratable(obj) &&
+           i915_gem_object_evictable(obj))
+               assert_object_held(obj);
+#endif
        return mr && (mr->type == INTEL_MEMORY_LOCAL ||
                      mr->type == INTEL_MEMORY_STOLEN_LOCAL);
 }

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
index 16eac5ea9238e733f1dc35c301e2a510bca6aeb9..cf18c430d51fad256101458fdccafa11d5fc2fb2 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
@@ -457,6 +457,24 @@ bool i915_gem_object_evictable(struct drm_i915_gem_object *obj)
        return pin_count == 0;
 }
 
+/**
+ * i915_gem_object_migratable - Whether the object is migratable out of the
+ * current region.
+ * @obj: Pointer to the object.
+ *
+ * Return: Whether the object is allowed to be resident in other
+ * regions than the current while pages are present.
+ */
+bool i915_gem_object_migratable(struct drm_i915_gem_object *obj)
+{
+       struct intel_memory_region *mr = READ_ONCE(obj->mm.region);
+
+       if (!mr)
+               return false;
+
+       return obj->mm.n_placements > 1;
+}
+
 void i915_gem_init__objects(struct drm_i915_private *i915)
 {
        INIT_WORK(&i915->mm.free_work, __i915_gem_free_work);

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index 5ae32ea99ee5ba400288cea3598f85f6da3acfbd..f8ce1483d1810f9d1fd22310fac77f0be9923265 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -596,6 +596,10 @@ void __i915_gem_free_object(struct drm_i915_gem_object *obj);
 
 bool i915_gem_object_evictable(struct drm_i915_gem_object *obj);
 
+bool i915_gem_object_migratable(struct drm_i915_gem_object *obj);
+
+bool i915_gem_object_validates_to_lmem(struct drm_i915_gem_object *obj);
+
 #ifdef CONFIG_MMU_NOTIFIER
 static inline bool
 i915_gem_object_is_userptr(struct drm_i915_gem_object *obj)