v4.19.13 snapshot.
diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
new file mode 100644
index 0000000..cba6b58
--- /dev/null
+++ b/drivers/xen/gntdev-dmabuf.c
@@ -0,0 +1,856 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Xen dma-buf functionality for gntdev.
+ *
+ * DMA buffer implementation is based on drivers/gpu/drm/drm_prime.c.
+ *
+ * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/dma-buf.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+
+#include <xen/xen.h>
+#include <xen/grant_table.h>
+
+#include "gntdev-common.h"
+#include "gntdev-dmabuf.h"
+
+#ifndef GRANT_INVALID_REF
+/*
+ * Note on usage of grant reference 0 as invalid grant reference:
+ * grant reference 0 is valid, but never exposed to a driver,
+ * because of the fact it is already in use/reserved by the PV console.
+ */
+#define GRANT_INVALID_REF 0
+#endif
+
+struct gntdev_dmabuf {
+ struct gntdev_dmabuf_priv *priv;
+ struct dma_buf *dmabuf;
+ struct list_head next;
+ int fd;
+
+ union {
+ struct {
+ /* Exported buffers are reference counted. */
+ struct kref refcount;
+
+ struct gntdev_priv *priv;
+ struct gntdev_grant_map *map;
+ } exp;
+ struct {
+ /* Granted references of the imported buffer. */
+ grant_ref_t *refs;
+ /* Scatter-gather table of the imported buffer. */
+ struct sg_table *sgt;
+ /* dma-buf attachment of the imported buffer. */
+ struct dma_buf_attachment *attach;
+ } imp;
+ } u;
+
+ /* Number of pages this buffer has. */
+ int nr_pages;
+ /* Pages of this buffer. */
+ struct page **pages;
+};
+
+struct gntdev_dmabuf_wait_obj {
+ struct list_head next;
+ struct gntdev_dmabuf *gntdev_dmabuf;
+ struct completion completion;
+};
+
+struct gntdev_dmabuf_attachment {
+ struct sg_table *sgt;
+ enum dma_data_direction dir;
+};
+
+struct gntdev_dmabuf_priv {
+ /* List of exported DMA buffers. */
+ struct list_head exp_list;
+ /* List of wait objects. */
+ struct list_head exp_wait_list;
+ /* List of imported DMA buffers. */
+ struct list_head imp_list;
+ /* This is the lock which protects dma_buf_xxx lists. */
+ struct mutex lock;
+};
+
+/* DMA buffer export support. */
+
+/* Implementation of wait for exported DMA buffer to be released. */
+
+static void dmabuf_exp_release(struct kref *kref);
+
+static struct gntdev_dmabuf_wait_obj *
+dmabuf_exp_wait_obj_new(struct gntdev_dmabuf_priv *priv,
+ struct gntdev_dmabuf *gntdev_dmabuf)
+{
+ struct gntdev_dmabuf_wait_obj *obj;
+
+ obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+ if (!obj)
+ return ERR_PTR(-ENOMEM);
+
+ init_completion(&obj->completion);
+ obj->gntdev_dmabuf = gntdev_dmabuf;
+
+ mutex_lock(&priv->lock);
+ list_add(&obj->next, &priv->exp_wait_list);
+ /* Put our reference and wait for gntdev_dmabuf's release to fire. */
+ kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
+ mutex_unlock(&priv->lock);
+ return obj;
+}
+
+static void dmabuf_exp_wait_obj_free(struct gntdev_dmabuf_priv *priv,
+ struct gntdev_dmabuf_wait_obj *obj)
+{
+ mutex_lock(&priv->lock);
+ list_del(&obj->next);
+ mutex_unlock(&priv->lock);
+ kfree(obj);
+}
+
+static int dmabuf_exp_wait_obj_wait(struct gntdev_dmabuf_wait_obj *obj,
+ u32 wait_to_ms)
+{
+ if (wait_for_completion_timeout(&obj->completion,
+ msecs_to_jiffies(wait_to_ms)) <= 0)
+ return -ETIMEDOUT;
+
+ return 0;
+}
+
+static void dmabuf_exp_wait_obj_signal(struct gntdev_dmabuf_priv *priv,
+ struct gntdev_dmabuf *gntdev_dmabuf)
+{
+ struct gntdev_dmabuf_wait_obj *obj;
+
+ list_for_each_entry(obj, &priv->exp_wait_list, next)
+ if (obj->gntdev_dmabuf == gntdev_dmabuf) {
+ pr_debug("Found gntdev_dmabuf in the wait list, wake\n");
+ complete_all(&obj->completion);
+ break;
+ }
+}
+
+static struct gntdev_dmabuf *
+dmabuf_exp_wait_obj_get_dmabuf(struct gntdev_dmabuf_priv *priv, int fd)
+{
+ struct gntdev_dmabuf *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
+
+ mutex_lock(&priv->lock);
+ list_for_each_entry(gntdev_dmabuf, &priv->exp_list, next)
+ if (gntdev_dmabuf->fd == fd) {
+ pr_debug("Found gntdev_dmabuf in the wait list\n");
+ kref_get(&gntdev_dmabuf->u.exp.refcount);
+ ret = gntdev_dmabuf;
+ break;
+ }
+ mutex_unlock(&priv->lock);
+ return ret;
+}
+
+static int dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd,
+ int wait_to_ms)
+{
+ struct gntdev_dmabuf *gntdev_dmabuf;
+ struct gntdev_dmabuf_wait_obj *obj;
+ int ret;
+
+ pr_debug("Will wait for dma-buf with fd %d\n", fd);
+ /*
+ * Try to find the DMA buffer: if not found means that
+ * either the buffer has already been released or file descriptor
+ * provided is wrong.
+ */
+ gntdev_dmabuf = dmabuf_exp_wait_obj_get_dmabuf(priv, fd);
+ if (IS_ERR(gntdev_dmabuf))
+ return PTR_ERR(gntdev_dmabuf);
+
+ /*
+ * gntdev_dmabuf still exists and is reference count locked by us now,
+ * so prepare to wait: allocate wait object and add it to the wait list,
+ * so we can find it on release.
+ */
+ obj = dmabuf_exp_wait_obj_new(priv, gntdev_dmabuf);
+ if (IS_ERR(obj))
+ return PTR_ERR(obj);
+
+ ret = dmabuf_exp_wait_obj_wait(obj, wait_to_ms);
+ dmabuf_exp_wait_obj_free(priv, obj);
+ return ret;
+}
+
+/* DMA buffer export support. */
+
+static struct sg_table *
+dmabuf_pages_to_sgt(struct page **pages, unsigned int nr_pages)
+{
+ struct sg_table *sgt;
+ int ret;
+
+ sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
+ if (!sgt) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ ret = sg_alloc_table_from_pages(sgt, pages, nr_pages, 0,
+ nr_pages << PAGE_SHIFT,
+ GFP_KERNEL);
+ if (ret)
+ goto out;
+
+ return sgt;
+
+out:
+ kfree(sgt);
+ return ERR_PTR(ret);
+}
+
+static int dmabuf_exp_ops_attach(struct dma_buf *dma_buf,
+ struct dma_buf_attachment *attach)
+{
+ struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach;
+
+ gntdev_dmabuf_attach = kzalloc(sizeof(*gntdev_dmabuf_attach),
+ GFP_KERNEL);
+ if (!gntdev_dmabuf_attach)
+ return -ENOMEM;
+
+ gntdev_dmabuf_attach->dir = DMA_NONE;
+ attach->priv = gntdev_dmabuf_attach;
+ return 0;
+}
+
+static void dmabuf_exp_ops_detach(struct dma_buf *dma_buf,
+ struct dma_buf_attachment *attach)
+{
+ struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
+
+ if (gntdev_dmabuf_attach) {
+ struct sg_table *sgt = gntdev_dmabuf_attach->sgt;
+
+ if (sgt) {
+ if (gntdev_dmabuf_attach->dir != DMA_NONE)
+ dma_unmap_sg_attrs(attach->dev, sgt->sgl,
+ sgt->nents,
+ gntdev_dmabuf_attach->dir,
+ DMA_ATTR_SKIP_CPU_SYNC);
+ sg_free_table(sgt);
+ }
+
+ kfree(sgt);
+ kfree(gntdev_dmabuf_attach);
+ attach->priv = NULL;
+ }
+}
+
+static struct sg_table *
+dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach,
+ enum dma_data_direction dir)
+{
+ struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
+ struct gntdev_dmabuf *gntdev_dmabuf = attach->dmabuf->priv;
+ struct sg_table *sgt;
+
+ pr_debug("Mapping %d pages for dev %p\n", gntdev_dmabuf->nr_pages,
+ attach->dev);
+
+ if (dir == DMA_NONE || !gntdev_dmabuf_attach)
+ return ERR_PTR(-EINVAL);
+
+ /* Return the cached mapping when possible. */
+ if (gntdev_dmabuf_attach->dir == dir)
+ return gntdev_dmabuf_attach->sgt;
+
+ /*
+ * Two mappings with different directions for the same attachment are
+ * not allowed.
+ */
+ if (gntdev_dmabuf_attach->dir != DMA_NONE)
+ return ERR_PTR(-EBUSY);
+
+ sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages,
+ gntdev_dmabuf->nr_pages);
+ if (!IS_ERR(sgt)) {
+ if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
+ DMA_ATTR_SKIP_CPU_SYNC)) {
+ sg_free_table(sgt);
+ kfree(sgt);
+ sgt = ERR_PTR(-ENOMEM);
+ } else {
+ gntdev_dmabuf_attach->sgt = sgt;
+ gntdev_dmabuf_attach->dir = dir;
+ }
+ }
+ if (IS_ERR(sgt))
+ pr_debug("Failed to map sg table for dev %p\n", attach->dev);
+ return sgt;
+}
+
+static void dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment *attach,
+ struct sg_table *sgt,
+ enum dma_data_direction dir)
+{
+ /* Not implemented. The unmap is done at dmabuf_exp_ops_detach(). */
+}
+
+static void dmabuf_exp_release(struct kref *kref)
+{
+ struct gntdev_dmabuf *gntdev_dmabuf =
+ container_of(kref, struct gntdev_dmabuf, u.exp.refcount);
+
+ dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf);
+ list_del(&gntdev_dmabuf->next);
+ kfree(gntdev_dmabuf);
+}
+
+static void dmabuf_exp_remove_map(struct gntdev_priv *priv,
+ struct gntdev_grant_map *map)
+{
+ mutex_lock(&priv->lock);
+ list_del(&map->next);
+ gntdev_put_map(NULL /* already removed */, map);
+ mutex_unlock(&priv->lock);
+}
+
+static void dmabuf_exp_ops_release(struct dma_buf *dma_buf)
+{
+ struct gntdev_dmabuf *gntdev_dmabuf = dma_buf->priv;
+ struct gntdev_dmabuf_priv *priv = gntdev_dmabuf->priv;
+
+ dmabuf_exp_remove_map(gntdev_dmabuf->u.exp.priv,
+ gntdev_dmabuf->u.exp.map);
+ mutex_lock(&priv->lock);
+ kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
+ mutex_unlock(&priv->lock);
+}
+
+static void *dmabuf_exp_ops_kmap(struct dma_buf *dma_buf,
+ unsigned long page_num)
+{
+ /* Not implemented. */
+ return NULL;
+}
+
+static void dmabuf_exp_ops_kunmap(struct dma_buf *dma_buf,
+ unsigned long page_num, void *addr)
+{
+ /* Not implemented. */
+}
+
+static int dmabuf_exp_ops_mmap(struct dma_buf *dma_buf,
+ struct vm_area_struct *vma)
+{
+ /* Not implemented. */
+ return 0;
+}
+
+static const struct dma_buf_ops dmabuf_exp_ops = {
+ .attach = dmabuf_exp_ops_attach,
+ .detach = dmabuf_exp_ops_detach,
+ .map_dma_buf = dmabuf_exp_ops_map_dma_buf,
+ .unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
+ .release = dmabuf_exp_ops_release,
+ .map = dmabuf_exp_ops_kmap,
+ .unmap = dmabuf_exp_ops_kunmap,
+ .mmap = dmabuf_exp_ops_mmap,
+};
+
+struct gntdev_dmabuf_export_args {
+ struct gntdev_priv *priv;
+ struct gntdev_grant_map *map;
+ struct gntdev_dmabuf_priv *dmabuf_priv;
+ struct device *dev;
+ int count;
+ struct page **pages;
+ u32 fd;
+};
+
+static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
+{
+ DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
+ struct gntdev_dmabuf *gntdev_dmabuf;
+ int ret;
+
+ gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
+ if (!gntdev_dmabuf)
+ return -ENOMEM;
+
+ kref_init(&gntdev_dmabuf->u.exp.refcount);
+
+ gntdev_dmabuf->priv = args->dmabuf_priv;
+ gntdev_dmabuf->nr_pages = args->count;
+ gntdev_dmabuf->pages = args->pages;
+ gntdev_dmabuf->u.exp.priv = args->priv;
+ gntdev_dmabuf->u.exp.map = args->map;
+
+ exp_info.exp_name = KBUILD_MODNAME;
+ if (args->dev->driver && args->dev->driver->owner)
+ exp_info.owner = args->dev->driver->owner;
+ else
+ exp_info.owner = THIS_MODULE;
+ exp_info.ops = &dmabuf_exp_ops;
+ exp_info.size = args->count << PAGE_SHIFT;
+ exp_info.flags = O_RDWR;
+ exp_info.priv = gntdev_dmabuf;
+
+ gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
+ if (IS_ERR(gntdev_dmabuf->dmabuf)) {
+ ret = PTR_ERR(gntdev_dmabuf->dmabuf);
+ gntdev_dmabuf->dmabuf = NULL;
+ goto fail;
+ }
+
+ ret = dma_buf_fd(gntdev_dmabuf->dmabuf, O_CLOEXEC);
+ if (ret < 0)
+ goto fail;
+
+ gntdev_dmabuf->fd = ret;
+ args->fd = ret;
+
+ pr_debug("Exporting DMA buffer with fd %d\n", ret);
+
+ mutex_lock(&args->dmabuf_priv->lock);
+ list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
+ mutex_unlock(&args->dmabuf_priv->lock);
+ return 0;
+
+fail:
+ if (gntdev_dmabuf->dmabuf)
+ dma_buf_put(gntdev_dmabuf->dmabuf);
+ kfree(gntdev_dmabuf);
+ return ret;
+}
+
+static struct gntdev_grant_map *
+dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
+ int count)
+{
+ struct gntdev_grant_map *map;
+
+ if (unlikely(count <= 0))
+ return ERR_PTR(-EINVAL);
+
+ if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
+ (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
+ pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
+ return ERR_PTR(-EINVAL);
+ }
+
+ map = gntdev_alloc_map(priv, count, dmabuf_flags);
+ if (!map)
+ return ERR_PTR(-ENOMEM);
+
+ if (unlikely(gntdev_account_mapped_pages(count))) {
+ pr_debug("can't map %d pages: over limit\n", count);
+ gntdev_put_map(NULL, map);
+ return ERR_PTR(-ENOMEM);
+ }
+ return map;
+}
+
+static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
+ int count, u32 domid, u32 *refs, u32 *fd)
+{
+ struct gntdev_grant_map *map;
+ struct gntdev_dmabuf_export_args args;
+ int i, ret;
+
+ map = dmabuf_exp_alloc_backing_storage(priv, flags, count);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
+
+ for (i = 0; i < count; i++) {
+ map->grants[i].domid = domid;
+ map->grants[i].ref = refs[i];
+ }
+
+ mutex_lock(&priv->lock);
+ gntdev_add_map(priv, map);
+ mutex_unlock(&priv->lock);
+
+ map->flags |= GNTMAP_host_map;
+#if defined(CONFIG_X86)
+ map->flags |= GNTMAP_device_map;
+#endif
+
+ ret = gntdev_map_grant_pages(map);
+ if (ret < 0)
+ goto out;
+
+ args.priv = priv;
+ args.map = map;
+ args.dev = priv->dma_dev;
+ args.dmabuf_priv = priv->dmabuf_priv;
+ args.count = map->count;
+ args.pages = map->pages;
+ args.fd = -1; /* Shut up unnecessary gcc warning for i386 */
+
+ ret = dmabuf_exp_from_pages(&args);
+ if (ret < 0)
+ goto out;
+
+ *fd = args.fd;
+ return 0;
+
+out:
+ dmabuf_exp_remove_map(priv, map);
+ return ret;
+}
+
+/* DMA buffer import support. */
+
+static int
+dmabuf_imp_grant_foreign_access(struct page **pages, u32 *refs,
+ int count, int domid)
+{
+ grant_ref_t priv_gref_head;
+ int i, ret;
+
+ ret = gnttab_alloc_grant_references(count, &priv_gref_head);
+ if (ret < 0) {
+ pr_debug("Cannot allocate grant references, ret %d\n", ret);
+ return ret;
+ }
+
+ for (i = 0; i < count; i++) {
+ int cur_ref;
+
+ cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
+ if (cur_ref < 0) {
+ ret = cur_ref;
+ pr_debug("Cannot claim grant reference, ret %d\n", ret);
+ goto out;
+ }
+
+ gnttab_grant_foreign_access_ref(cur_ref, domid,
+ xen_page_to_gfn(pages[i]), 0);
+ refs[i] = cur_ref;
+ }
+
+ return 0;
+
+out:
+ gnttab_free_grant_references(priv_gref_head);
+ return ret;
+}
+
+static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
+{
+ int i;
+
+ for (i = 0; i < count; i++)
+ if (refs[i] != GRANT_INVALID_REF)
+ gnttab_end_foreign_access(refs[i], 0, 0UL);
+}
+
+static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
+{
+ kfree(gntdev_dmabuf->pages);
+ kfree(gntdev_dmabuf->u.imp.refs);
+ kfree(gntdev_dmabuf);
+}
+
+static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
+{
+ struct gntdev_dmabuf *gntdev_dmabuf;
+ int i;
+
+ gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
+ if (!gntdev_dmabuf)
+ goto fail_no_free;
+
+ gntdev_dmabuf->u.imp.refs = kcalloc(count,
+ sizeof(gntdev_dmabuf->u.imp.refs[0]),
+ GFP_KERNEL);
+ if (!gntdev_dmabuf->u.imp.refs)
+ goto fail;
+
+ gntdev_dmabuf->pages = kcalloc(count,
+ sizeof(gntdev_dmabuf->pages[0]),
+ GFP_KERNEL);
+ if (!gntdev_dmabuf->pages)
+ goto fail;
+
+ gntdev_dmabuf->nr_pages = count;
+
+ for (i = 0; i < count; i++)
+ gntdev_dmabuf->u.imp.refs[i] = GRANT_INVALID_REF;
+
+ return gntdev_dmabuf;
+
+fail:
+ dmabuf_imp_free_storage(gntdev_dmabuf);
+fail_no_free:
+ return ERR_PTR(-ENOMEM);
+}
+
+static struct gntdev_dmabuf *
+dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
+ int fd, int count, int domid)
+{
+ struct gntdev_dmabuf *gntdev_dmabuf, *ret;
+ struct dma_buf *dma_buf;
+ struct dma_buf_attachment *attach;
+ struct sg_table *sgt;
+ struct sg_page_iter sg_iter;
+ int i;
+
+ dma_buf = dma_buf_get(fd);
+ if (IS_ERR(dma_buf))
+ return ERR_CAST(dma_buf);
+
+ gntdev_dmabuf = dmabuf_imp_alloc_storage(count);
+ if (IS_ERR(gntdev_dmabuf)) {
+ ret = gntdev_dmabuf;
+ goto fail_put;
+ }
+
+ gntdev_dmabuf->priv = priv;
+ gntdev_dmabuf->fd = fd;
+
+ attach = dma_buf_attach(dma_buf, dev);
+ if (IS_ERR(attach)) {
+ ret = ERR_CAST(attach);
+ goto fail_free_obj;
+ }
+
+ gntdev_dmabuf->u.imp.attach = attach;
+
+ sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
+ if (IS_ERR(sgt)) {
+ ret = ERR_CAST(sgt);
+ goto fail_detach;
+ }
+
+ /* Check number of pages that imported buffer has. */
+ if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) {
+ ret = ERR_PTR(-EINVAL);
+ pr_debug("DMA buffer has %zu pages, user-space expects %d\n",
+ attach->dmabuf->size, gntdev_dmabuf->nr_pages);
+ goto fail_unmap;
+ }
+
+ gntdev_dmabuf->u.imp.sgt = sgt;
+
+ /* Now convert sgt to array of pages and check for page validity. */
+ i = 0;
+ for_each_sg_page(sgt->sgl, &sg_iter, sgt->nents, 0) {
+ struct page *page = sg_page_iter_page(&sg_iter);
+ /*
+ * Check if page is valid: this can happen if we are given
+ * a page from VRAM or other resources which are not backed
+ * by a struct page.
+ */
+ if (!pfn_valid(page_to_pfn(page))) {
+ ret = ERR_PTR(-EINVAL);
+ goto fail_unmap;
+ }
+
+ gntdev_dmabuf->pages[i++] = page;
+ }
+
+ ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gntdev_dmabuf->pages,
+ gntdev_dmabuf->u.imp.refs,
+ count, domid));
+ if (IS_ERR(ret))
+ goto fail_end_access;
+
+ pr_debug("Imported DMA buffer with fd %d\n", fd);
+
+ mutex_lock(&priv->lock);
+ list_add(&gntdev_dmabuf->next, &priv->imp_list);
+ mutex_unlock(&priv->lock);
+
+ return gntdev_dmabuf;
+
+fail_end_access:
+ dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs, count);
+fail_unmap:
+ dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
+fail_detach:
+ dma_buf_detach(dma_buf, attach);
+fail_free_obj:
+ dmabuf_imp_free_storage(gntdev_dmabuf);
+fail_put:
+ dma_buf_put(dma_buf);
+ return ret;
+}
+
+/*
+ * Find the hyper dma-buf by its file descriptor and remove
+ * it from the buffer's list.
+ */
+static struct gntdev_dmabuf *
+dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv *priv, int fd)
+{
+ struct gntdev_dmabuf *q, *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
+
+ mutex_lock(&priv->lock);
+ list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next) {
+ if (gntdev_dmabuf->fd == fd) {
+ pr_debug("Found gntdev_dmabuf in the import list\n");
+ ret = gntdev_dmabuf;
+ list_del(&gntdev_dmabuf->next);
+ break;
+ }
+ }
+ mutex_unlock(&priv->lock);
+ return ret;
+}
+
+static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
+{
+ struct gntdev_dmabuf *gntdev_dmabuf;
+ struct dma_buf_attachment *attach;
+ struct dma_buf *dma_buf;
+
+ gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
+ if (IS_ERR(gntdev_dmabuf))
+ return PTR_ERR(gntdev_dmabuf);
+
+ pr_debug("Releasing DMA buffer with fd %d\n", fd);
+
+ dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
+ gntdev_dmabuf->nr_pages);
+
+ attach = gntdev_dmabuf->u.imp.attach;
+
+ if (gntdev_dmabuf->u.imp.sgt)
+ dma_buf_unmap_attachment(attach, gntdev_dmabuf->u.imp.sgt,
+ DMA_BIDIRECTIONAL);
+ dma_buf = attach->dmabuf;
+ dma_buf_detach(attach->dmabuf, attach);
+ dma_buf_put(dma_buf);
+
+ dmabuf_imp_free_storage(gntdev_dmabuf);
+ return 0;
+}
+
+/* DMA buffer IOCTL support. */
+
+long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
+ struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
+{
+ struct ioctl_gntdev_dmabuf_exp_from_refs op;
+ u32 *refs;
+ long ret;
+
+ if (use_ptemod) {
+ pr_debug("Cannot provide dma-buf: use_ptemode %d\n",
+ use_ptemod);
+ return -EINVAL;
+ }
+
+ if (copy_from_user(&op, u, sizeof(op)) != 0)
+ return -EFAULT;
+
+ if (unlikely(op.count <= 0))
+ return -EINVAL;
+
+ refs = kcalloc(op.count, sizeof(*refs), GFP_KERNEL);
+ if (!refs)
+ return -ENOMEM;
+
+ if (copy_from_user(refs, u->refs, sizeof(*refs) * op.count) != 0) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
+ op.domid, refs, &op.fd);
+ if (ret)
+ goto out;
+
+ if (copy_to_user(u, &op, sizeof(op)) != 0)
+ ret = -EFAULT;
+
+out:
+ kfree(refs);
+ return ret;
+}
+
+long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
+ struct ioctl_gntdev_dmabuf_exp_wait_released __user *u)
+{
+ struct ioctl_gntdev_dmabuf_exp_wait_released op;
+
+ if (copy_from_user(&op, u, sizeof(op)) != 0)
+ return -EFAULT;
+
+ return dmabuf_exp_wait_released(priv->dmabuf_priv, op.fd,
+ op.wait_to_ms);
+}
+
+long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
+ struct ioctl_gntdev_dmabuf_imp_to_refs __user *u)
+{
+ struct ioctl_gntdev_dmabuf_imp_to_refs op;
+ struct gntdev_dmabuf *gntdev_dmabuf;
+ long ret;
+
+ if (copy_from_user(&op, u, sizeof(op)) != 0)
+ return -EFAULT;
+
+ if (unlikely(op.count <= 0))
+ return -EINVAL;
+
+ gntdev_dmabuf = dmabuf_imp_to_refs(priv->dmabuf_priv,
+ priv->dma_dev, op.fd,
+ op.count, op.domid);
+ if (IS_ERR(gntdev_dmabuf))
+ return PTR_ERR(gntdev_dmabuf);
+
+ if (copy_to_user(u->refs, gntdev_dmabuf->u.imp.refs,
+ sizeof(*u->refs) * op.count) != 0) {
+ ret = -EFAULT;
+ goto out_release;
+ }
+ return 0;
+
+out_release:
+ dmabuf_imp_release(priv->dmabuf_priv, op.fd);
+ return ret;
+}
+
+long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
+ struct ioctl_gntdev_dmabuf_imp_release __user *u)
+{
+ struct ioctl_gntdev_dmabuf_imp_release op;
+
+ if (copy_from_user(&op, u, sizeof(op)) != 0)
+ return -EFAULT;
+
+ return dmabuf_imp_release(priv->dmabuf_priv, op.fd);
+}
+
+struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void)
+{
+ struct gntdev_dmabuf_priv *priv;
+
+ priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return ERR_PTR(-ENOMEM);
+
+ mutex_init(&priv->lock);
+ INIT_LIST_HEAD(&priv->exp_list);
+ INIT_LIST_HEAD(&priv->exp_wait_list);
+ INIT_LIST_HEAD(&priv->imp_list);
+
+ return priv;
+}
+
+void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
+{
+ kfree(priv);
+}