i915_gem_dmabuf.c

/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright 2012 Red Hat Inc
 */

#include <linux/dma-buf.h>
#include <linux/highmem.h>
#include <linux/dma-resv.h>

#include "i915_drv.h"
#include "i915_gem_object.h"
#include "i915_scatterlist.h"

I915_SELFTEST_DECLARE(static bool force_different_devices;)

static struct drm_i915_gem_object *dma_buf_to_obj(struct dma_buf *buf)
{
	return to_intel_bo(buf->priv);
}

static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachment,
					     enum dma_data_direction dir)
{
	struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment->dmabuf);
	struct sg_table *st;
	struct scatterlist *src, *dst;
	int ret, i;

	/* Copy sg so that we make an independent mapping */
	st = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
	if (st == NULL) {
		ret = -ENOMEM;
		goto err;
	}

	ret = sg_alloc_table(st, obj->mm.pages->nents, GFP_KERNEL);
	if (ret)
		goto err_free;

	src = obj->mm.pages->sgl;
	dst = st->sgl;
	for (i = 0; i < obj->mm.pages->nents; i++) {
		sg_set_page(dst, sg_page(src), src->length, 0);
		dst = sg_next(dst);
		src = sg_next(src);
	}

	ret = dma_map_sgtable(attachment->dev, st, dir, DMA_ATTR_SKIP_CPU_SYNC);
	if (ret)
		goto err_free_sg;

	return st;

err_free_sg:
	sg_free_table(st);
err_free:
	kfree(st);
err:
	return ERR_PTR(ret);
}

static void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
				   struct sg_table *sg,
				   enum dma_data_direction dir)
{
	dma_unmap_sgtable(attachment->dev, sg, dir, DMA_ATTR_SKIP_CPU_SYNC);
	sg_free_table(sg);
	kfree(sg);
}

static int i915_gem_dmabuf_vmap(struct dma_buf *dma_buf, struct dma_buf_map *map)
{
	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
	void *vaddr;

	vaddr = i915_gem_object_pin_map_unlocked(obj, I915_MAP_WB);
	if (IS_ERR(vaddr))
		return PTR_ERR(vaddr);

	dma_buf_map_set_vaddr(map, vaddr);

	return 0;
}

static void i915_gem_dmabuf_vunmap(struct dma_buf *dma_buf, struct dma_buf_map *map)
{
	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);

	i915_gem_object_flush_map(obj);
	i915_gem_object_unpin_map(obj);
}

static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
{
	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
	int ret;

	if (obj->base.size < vma->vm_end - vma->vm_start)
		return -EINVAL;

	if (!obj->base.filp)
		return -ENODEV;

	ret = call_mmap(obj->base.filp, vma);
	if (ret)
		return ret;

	vma_set_file(vma, obj->base.filp);

	return 0;
}

static int i915_gem_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)
{
	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
	bool write = (direction == DMA_BIDIRECTIONAL || direction == DMA_TO_DEVICE);
	struct i915_gem_ww_ctx ww;
	int err;

	i915_gem_ww_ctx_init(&ww, true);
retry:
	err = i915_gem_object_lock(obj, &ww);
	if (!err)
		err = i915_gem_object_pin_pages(obj);
	if (!err) {
		err = i915_gem_object_set_to_cpu_domain(obj, write);
		i915_gem_object_unpin_pages(obj);
	}
	if (err == -EDEADLK) {
		err = i915_gem_ww_ctx_backoff(&ww);
		if (!err)
			goto retry;
	}
	i915_gem_ww_ctx_fini(&ww);
	return err;
}

static int i915_gem_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)
{
	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
	struct i915_gem_ww_ctx ww;
	int err;

	i915_gem_ww_ctx_init(&ww, true);
retry:
	err = i915_gem_object_lock(obj, &ww);
	if (!err)
		err = i915_gem_object_pin_pages(obj);
	if (!err) {
		err = i915_gem_object_set_to_gtt_domain(obj, false);
		i915_gem_object_unpin_pages(obj);
	}
	if (err == -EDEADLK) {
		err = i915_gem_ww_ctx_backoff(&ww);
		if (!err)
			goto retry;
	}
	i915_gem_ww_ctx_fini(&ww);
	return err;
}

/**
 * i915_gem_dmabuf_attach - Do any extra attach work necessary
 * @dmabuf: imported dma-buf
 * @attach: new attach to do work on
 *
 */
static int i915_gem_dmabuf_attach(struct dma_buf *dmabuf,
				  struct dma_buf_attachment *attach)
{
	struct drm_i915_gem_object *obj = dma_buf_to_obj(dmabuf);

	assert_object_held(obj);
	return i915_gem_object_pin_pages(obj);
}

static void i915_gem_dmabuf_detach(struct dma_buf *dmabuf,
				   struct dma_buf_attachment *attach)
{
	struct drm_i915_gem_object *obj = dma_buf_to_obj(dmabuf);

	i915_gem_object_unpin_pages(obj);
}

static const struct dma_buf_ops i915_dmabuf_ops =  {
	.attach = i915_gem_dmabuf_attach,
	.detach = i915_gem_dmabuf_detach,
	.map_dma_buf = i915_gem_map_dma_buf,
	.unmap_dma_buf = i915_gem_unmap_dma_buf,
	.release = drm_gem_dmabuf_release,
	.mmap = i915_gem_dmabuf_mmap,
	.vmap = i915_gem_dmabuf_vmap,
	.vunmap = i915_gem_dmabuf_vunmap,
	.begin_cpu_access = i915_gem_begin_cpu_access,
	.end_cpu_access = i915_gem_end_cpu_access,
};

struct dma_buf *i915_gem_prime_export(struct drm_gem_object *gem_obj, int flags)
{
	struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);
	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);

	exp_info.ops = &i915_dmabuf_ops;
	exp_info.size = gem_obj->size;
	exp_info.flags = flags;
	exp_info.priv = gem_obj;
	exp_info.resv = obj->base.resv;

	if (obj->ops->dmabuf_export) {
		int ret = obj->ops->dmabuf_export(obj);
		if (ret)
			return ERR_PTR(ret);
	}

	return drm_gem_dmabuf_export(gem_obj->dev, &exp_info);
}

static int i915_gem_object_get_pages_dmabuf(struct drm_i915_gem_object *obj)
{
	struct sg_table *pages;
	unsigned int sg_page_sizes;

	assert_object_held(obj);

	pages = dma_buf_map_attachment(obj->base.import_attach,
				       DMA_BIDIRECTIONAL);
	if (IS_ERR(pages))
		return PTR_ERR(pages);

	sg_page_sizes = i915_sg_dma_sizes(pages->sgl);

	__i915_gem_object_set_pages(obj, pages, sg_page_sizes);

	return 0;
}

static void i915_gem_object_put_pages_dmabuf(struct drm_i915_gem_object *obj,
					     struct sg_table *pages)
{
	dma_buf_unmap_attachment(obj->base.import_attach, pages,
				 DMA_BIDIRECTIONAL);
}

static const struct drm_i915_gem_object_ops i915_gem_object_dmabuf_ops = {
	.name = "i915_gem_object_dmabuf",
	.get_pages = i915_gem_object_get_pages_dmabuf,
	.put_pages = i915_gem_object_put_pages_dmabuf,
};

struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
					     struct dma_buf *dma_buf)
{
	static struct lock_class_key lock_class;
	struct dma_buf_attachment *attach;
	struct drm_i915_gem_object *obj;
	int ret;

	/* is this one of own objects? */
	if (dma_buf->ops == &i915_dmabuf_ops) {
		obj = dma_buf_to_obj(dma_buf);
		/* is it from our device? */
		if (obj->base.dev == dev &&
		    !I915_SELFTEST_ONLY(force_different_devices)) {
			/*
			 * Importing dmabuf exported from out own gem increases
			 * refcount on gem itself instead of f_count of dmabuf.
			 */
			return &i915_gem_object_get(obj)->base;
		}
	}

	if (i915_gem_object_size_2big(dma_buf->size))
		return ERR_PTR(-E2BIG);

	/* need to attach */
	attach = dma_buf_attach(dma_buf, dev->dev);
	if (IS_ERR(attach))
		return ERR_CAST(attach);

	get_dma_buf(dma_buf);

	obj = i915_gem_object_alloc();
	if (obj == NULL) {
		ret = -ENOMEM;
		goto fail_detach;
	}

	drm_gem_private_object_init(dev, &obj->base, dma_buf->size);
	i915_gem_object_init(obj, &i915_gem_object_dmabuf_ops, &lock_class, 0);
	obj->base.import_attach = attach;
	obj->base.resv = dma_buf->resv;

	/* We use GTT as shorthand for a coherent domain, one that is
	 * neither in the GPU cache nor in the CPU cache, where all
	 * writes are immediately visible in memory. (That's not strictly
	 * true, but it's close! There are internal buffers such as the
	 * write-combined buffer or a delay through the chipset for GTT
	 * writes that do require us to treat GTT as a separate cache domain.)
	 */
	obj->read_domains = I915_GEM_DOMAIN_GTT;
	obj->write_domain = 0;

	return &obj->base;

fail_detach:
	dma_buf_detach(dma_buf, attach);
	dma_buf_put(dma_buf);

	return ERR_PTR(ret);
}

#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftests/mock_dmabuf.c"
#include "selftests/i915_gem_dmabuf.c"
#endif