drm/i915: introduce intel_memory_region

Support memory regions, as defined by a given (start, end), and allow
creating GEM objects which are backed by said region. The immediate goal
here is to have something to represent our device memory, but later on
we also want to represent every memory domain with a region, so stolen,
shmem, and of course device. At some point we are probably going to want
use a common struct here, such that we are better aligned with say TTM.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191008160116.18379-2-matthew.auld@intel.com

1 files changed, 145 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_region.c b/drivers/gpu/drm/i915/gem/i915_gem_region.c
new file mode 100644
index 000000000000..6588e3c99e5d
--- /dev/null
+++ b/drivers/gpu/drm/i915/gem/i915_gem_region.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2019 Intel Corporation
+ */
+
+#include "intel_memory_region.h"
+#include "i915_gem_region.h"
+#include "i915_drv.h"
+
+void
+i915_gem_object_put_pages_buddy(struct drm_i915_gem_object *obj,
+				struct sg_table *pages)
+{
+	__intel_memory_region_put_pages_buddy(obj->mm.region, &obj->mm.blocks);
+
+	obj->mm.dirty = false;
+	sg_free_table(pages);
+	kfree(pages);
+}
+
+int
+i915_gem_object_get_pages_buddy(struct drm_i915_gem_object *obj)
+{
+	struct intel_memory_region *mem = obj->mm.region;
+	struct list_head *blocks = &obj->mm.blocks;
+	unsigned int flags = I915_ALLOC_MIN_PAGE_SIZE;
+	resource_size_t size = obj->base.size;
+	resource_size_t prev_end;
+	struct i915_buddy_block *block;
+	struct sg_table *st;
+	struct scatterlist *sg;
+	unsigned int sg_page_sizes;
+	int ret;
+
+	st = kmalloc(sizeof(*st), GFP_KERNEL);
+	if (!st)
+		return -ENOMEM;
+
+	if (sg_alloc_table(st, size >> ilog2(mem->mm.chunk_size), GFP_KERNEL)) {
+		kfree(st);
+		return -ENOMEM;
+	}
+
+	ret = __intel_memory_region_get_pages_buddy(mem, size, flags, blocks);
+	if (ret)
+		goto err_free_sg;
+
+	GEM_BUG_ON(list_empty(blocks));
+
+	sg = st->sgl;
+	st->nents = 0;
+	sg_page_sizes = 0;
+	prev_end = (resource_size_t)-1;
+
+	list_for_each_entry(block, blocks, link) {
+		u64 block_size, offset;
+
+		block_size = i915_buddy_block_size(&mem->mm, block);
+		offset = i915_buddy_block_offset(block);
+
+		GEM_BUG_ON(overflows_type(block_size, sg->length));
+
+		if (offset != prev_end ||
+		    add_overflows_t(typeof(sg->length), sg->length, block_size)) {
+			if (st->nents) {
+				sg_page_sizes |= sg->length;
+				sg = __sg_next(sg);
+			}
+
+			sg_dma_address(sg) = mem->region.start + offset;
+			sg_dma_len(sg) = block_size;
+
+			sg->length = block_size;
+
+			st->nents++;
+		} else {
+			sg->length += block_size;
+			sg_dma_len(sg) += block_size;
+		}
+
+		prev_end = offset + block_size;
+	};
+
+	sg_page_sizes |= sg->length;
+	sg_mark_end(sg);
+	i915_sg_trim(st);
+
+	__i915_gem_object_set_pages(obj, st, sg_page_sizes);
+
+	return 0;
+
+err_free_sg:
+	sg_free_table(st);
+	kfree(st);
+	return ret;
+}
+
+void i915_gem_object_init_memory_region(struct drm_i915_gem_object *obj,
+					struct intel_memory_region *mem)
+{
+	INIT_LIST_HEAD(&obj->mm.blocks);
+	obj->mm.region = intel_memory_region_get(mem);
+}
+
+void i915_gem_object_release_memory_region(struct drm_i915_gem_object *obj)
+{
+	intel_memory_region_put(obj->mm.region);
+}
+
+struct drm_i915_gem_object *
+i915_gem_object_create_region(struct intel_memory_region *mem,
+			      resource_size_t size,
+			      unsigned int flags)
+{
+	struct drm_i915_gem_object *obj;
+
+	/*
+	 * NB: Our use of resource_size_t for the size stems from using struct
+	 * resource for the mem->region. We might need to revisit this in the
+	 * future.
+	 */
+
+	if (!mem)
+		return ERR_PTR(-ENODEV);
+
+	size = round_up(size, mem->min_page_size);
+
+	GEM_BUG_ON(!size);
+	GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_MIN_ALIGNMENT));
+
+	/*
+	 * XXX: There is a prevalence of the assumption that we fit the
+	 * object's page count inside a 32bit _signed_ variable. Let's document
+	 * this and catch if we ever need to fix it. In the meantime, if you do
+	 * spot such a local variable, please consider fixing!
+	 */
+
+	if (size >> PAGE_SHIFT > INT_MAX)
+		return ERR_PTR(-E2BIG);
+
+	if (overflows_type(size, obj->base.size))
+		return ERR_PTR(-E2BIG);
+
+	return mem->ops->create_object(mem, size, flags);
+}