[PATCH 05/11] drm/i915: Support for creating Stolen memory backed objects

[ankitprasad.r.sharma@intel.com]

From: Ankitprasad Sharma <ankitprasad.r.sharma@intel.com>

Extend the drm_i915_gem_create structure to add support for
creating Stolen memory backed objects. Added a new flag through
which user can specify the preference to allocate the object from
stolen memory, which if set, an attempt will be made to allocate
the object from stolen memory subject to the availability of
free space in the stolen region.

v2: Rebased to the latest drm-intel-nightly (Ankit)

v3: Changed versioning of GEM_CREATE param, added new comments (Tvrtko)

v4: Changed size from 32b to 64b to prevent userspace overflow (Tvrtko)
Corrected function arguments ordering (Chris)

v5: Corrected function name (Chris)

v6: Updated datatype for flags to keep sizeof(drm_i915_gem_create) u64
aligned (Chris)

v7: Use first 8 bits of gem_create flags for placement (Chris), Add helper
function for object allocation from stolen region (Ankit)

v8: Added comment explaining STOLEN placement flag (Chris)

Testcase: igt/gem_stolen

Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sharma@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_dma.c        |  3 +++
 drivers/gpu/drm/i915/i915_drv.h        |  2 +-
 drivers/gpu/drm/i915/i915_gem.c        | 49 ++++++++++++++++++++++++++++++----
 drivers/gpu/drm/i915/i915_gem_stolen.c |  4 +--
 include/uapi/drm/i915_drm.h            | 41 ++++++++++++++++++++++++++++
 5 files changed, 91 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 07edaed..83ae436 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -231,6 +231,9 @@ static int i915_getparam(struct drm_device *dev, void *data,
 	case I915_PARAM_HAS_EXEC_SOFTPIN:
 		value = 1;
 		break;
+	case I915_PARAM_CREATE_VERSION:
+		value = 2;
+		break;
 	default:
 		DRM_DEBUG("Unknown parameter %d\n", param->param);
 		return -EINVAL;
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 96eea3d..c92cb60 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3523,7 +3523,7 @@ void i915_gem_stolen_remove_node(struct drm_i915_private *dev_priv,
 int i915_gem_init_stolen(struct drm_device *dev);
 void i915_gem_cleanup_stolen(struct drm_device *dev);
 struct drm_i915_gem_object *
-i915_gem_object_create_stolen(struct drm_device *dev, u32 size);
+i915_gem_object_create_stolen(struct drm_device *dev, u64 size);
 struct drm_i915_gem_object *
 i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 					       u32 stolen_offset,
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d658d46..28c7e28 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -384,10 +384,36 @@ void i915_gem_object_free(struct drm_i915_gem_object *obj)
 	kmem_cache_free(dev_priv->objects, obj);
 }
 
+static struct drm_i915_gem_object *
+i915_gem_alloc_object_stolen(struct drm_device *dev, size_t size)
+{
+	struct drm_i915_gem_object *obj;
+	int ret;
+
+	mutex_lock(&dev->struct_mutex);
+	obj = i915_gem_object_create_stolen(dev, size);
+	if (!obj) {
+		mutex_unlock(&dev->struct_mutex);
+		return NULL;
+	}
+
+	/* Always clear fresh buffers before handing to userspace */
+	ret = i915_gem_object_clear(obj);
+	if (ret) {
+		drm_gem_object_unreference(&obj->base);
+		mutex_unlock(&dev->struct_mutex);
+		return NULL;
+	}
+
+	mutex_unlock(&dev->struct_mutex);
+	return obj;
+}
+
 static int
 i915_gem_create(struct drm_file *file,
 		struct drm_device *dev,
 		uint64_t size,
+		uint64_t flags,
 		uint32_t *handle_p)
 {
 	struct drm_i915_gem_object *obj;
@@ -398,10 +424,23 @@ i915_gem_create(struct drm_file *file,
 	if (size == 0)
 		return -EINVAL;
 
+	if (flags & __I915_CREATE_UNKNOWN_FLAGS)
+		return -EINVAL;
+
 	/* Allocate the new object */
-	obj = i915_gem_object_create(dev, size);
-	if (IS_ERR(obj))
-		return PTR_ERR(obj);
+	switch (flags & I915_CREATE_PLACEMENT_MASK) {
+	case I915_CREATE_PLACEMENT_NORMAL:
+		obj = i915_gem_object_create(dev, size);
+		break;
+	case I915_CREATE_PLACEMENT_STOLEN:
+		obj = i915_gem_alloc_object_stolen(dev, size);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (IS_ERR_OR_NULL(obj))
+		return -ENOMEM;
 
 	ret = drm_gem_handle_create(file, &obj->base, &handle);
 	/* drop reference from allocate - handle holds it now */
@@ -422,7 +461,7 @@ i915_gem_dumb_create(struct drm_file *file,
 	args->pitch = ALIGN(args->width * DIV_ROUND_UP(args->bpp, 8), 64);
 	args->size = args->pitch * args->height;
 	return i915_gem_create(file, dev,
-			       args->size, &args->handle);
+			       args->size, 0, &args->handle);
 }
 
 /**
@@ -438,7 +477,7 @@ i915_gem_create_ioctl(struct drm_device *dev, void *data,
 	struct drm_i915_gem_create *args = data;
 
 	return i915_gem_create(file, dev,
-			       args->size, &args->handle);
+			       args->size, args->flags, &args->handle);
 }
 
 static inline int
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index f9253f2..81d5b6b 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -597,7 +597,7 @@ cleanup:
 }
 
 struct drm_i915_gem_object *
-i915_gem_object_create_stolen(struct drm_device *dev, u32 size)
+i915_gem_object_create_stolen(struct drm_device *dev, u64 size)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_gem_object *obj;
@@ -607,7 +607,7 @@ i915_gem_object_create_stolen(struct drm_device *dev, u32 size)
 	if (!drm_mm_initialized(&dev_priv->mm.stolen))
 		return NULL;
 
-	DRM_DEBUG_KMS("creating stolen object: size=%x\n", size);
+	DRM_DEBUG_KMS("creating stolen object: size=%llx\n", size);
 	if (size == 0)
 		return NULL;
 
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index c17d63d..ceff4c1 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -361,6 +361,7 @@ typedef struct drm_i915_irq_wait {
 #define I915_PARAM_HAS_GPU_RESET	 35
 #define I915_PARAM_HAS_RESOURCE_STREAMER 36
 #define I915_PARAM_HAS_EXEC_SOFTPIN	 37
+#define I915_PARAM_CREATE_VERSION	 38
 
 typedef struct drm_i915_getparam {
 	__s32 param;
@@ -460,6 +461,46 @@ struct drm_i915_gem_create {
 	 */
 	__u32 handle;
 	__u32 pad;
+	/**
+	 * Requested flags (currently used for placement
+	 * (which memory domain))
+	 *
+	 * You can request that the object be created from special memory
+	 * rather than regular system pages using this parameter. Such
+	 * irregular objects may have certain restrictions (such as CPU
+	 * access to a stolen object is verboten).
+	 *
+	 * This can be used in the future for other purposes too
+	 * e.g. specifying tiling/caching/madvise
+	 */
+	__u64 flags;
+#define I915_CREATE_PLACEMENT_NORMAL 	0 /* standard swappable bo  */
+/* Allocate the object from memory reserved for the igfx (stolen).
+ *
+ * Objects allocated from stolen are restricted in the API they can use,
+ * as direct CPU access to stolen memory is prohibited by the system.
+ * This means that you cannot use a regular CPU mmap (either using WB
+ * or with the WC extension). You can still use a GTT mmap, pwrite,
+ * pread and pass it around for use by execbuffer and between processes
+ * like normal.
+ *
+ * Stolen memory is a very limited resource and certain functions of the
+ * hardware can only work from within stolen memory. Userspace's
+ * allocations may be evicted from stolen and moved to normal memory as
+ * required. If the allocation is marked as purgeable (using madvise),
+ * the allocation will be dropped and further access to the object's
+ * backing storage will result in -EFAULT. Stolen objects will also be
+ * migrated to normal memory across suspend and resume, as the stolen
+ * memory is not preserved.
+ *
+ * Stolen memory is regarded as a resource placement hint, most suitable
+ * for medium-sized buffers that are only accessed by the GPU and can be
+ * discarded.
+ */
+#define I915_CREATE_PLACEMENT_STOLEN 	1 /* Cannot use CPU mmaps */
+
+#define I915_CREATE_PLACEMENT_MASK	0xff
+#define __I915_CREATE_UNKNOWN_FLAGS	~I915_CREATE_PLACEMENT_MASK
 };
 
 struct drm_i915_gem_pread {
-- 
1.9.1

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