xen/gntdev: Implement dma-buf export functionality
1. Create a dma-buf from grant references provided by the foreign domain. By default dma-buf is backed by system memory pages, but by providing GNTDEV_DMA_FLAG_XXX flags it can also be created as a DMA write-combine/coherent buffer, e.g. allocated with corresponding dma_alloc_xxx API. Export the resulting buffer as a new dma-buf. 2. Implement waiting for the dma-buf to be released: block until the dma-buf with the file descriptor provided is released. If within the time-out provided the buffer is not released then -ETIMEDOUT error is returned. If the buffer with the file descriptor does not exist or has already been released, then -ENOENT is returned. For valid file descriptors this must not be treated as error. 3. Make gntdev's common code and structures available to dma-buf. [boris: added 'args.fd = -1' to dmabuf_exp_from_refs() to avoid an unnecessary warning about it not being initialized on i386 with gcc 8.1.1] Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
This commit is contained in:
Oleksandr Andrushchenko
Boris Ostrovsky
parent
932d656217
commit
a240d6e42e
@ -3,11 +3,14 @@
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/*
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* Xen dma-buf functionality for gntdev.
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*
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* DMA buffer implementation is based on drivers/gpu/drm/drm_prime.c.
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*
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* Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
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*/
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/dma-buf.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/uaccess.h>
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@ -18,6 +21,39 @@
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#include "gntdev-common.h"
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#include "gntdev-dmabuf.h"
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struct gntdev_dmabuf {
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struct gntdev_dmabuf_priv *priv;
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struct dma_buf *dmabuf;
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struct list_head next;
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int fd;
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union {
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struct {
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/* Exported buffers are reference counted. */
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struct kref refcount;
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struct gntdev_priv *priv;
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struct gntdev_grant_map *map;
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} exp;
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} u;
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/* Number of pages this buffer has. */
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int nr_pages;
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/* Pages of this buffer. */
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struct page **pages;
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};
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struct gntdev_dmabuf_wait_obj {
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struct list_head next;
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struct gntdev_dmabuf *gntdev_dmabuf;
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struct completion completion;
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};
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struct gntdev_dmabuf_attachment {
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struct sg_table *sgt;
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enum dma_data_direction dir;
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};
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struct gntdev_dmabuf_priv {
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/* List of exported DMA buffers. */
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struct list_head exp_list;
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@ -31,17 +67,427 @@ struct gntdev_dmabuf_priv {
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/* Implementation of wait for exported DMA buffer to be released. */
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static void dmabuf_exp_release(struct kref *kref);
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static struct gntdev_dmabuf_wait_obj *
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dmabuf_exp_wait_obj_new(struct gntdev_dmabuf_priv *priv,
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struct gntdev_dmabuf *gntdev_dmabuf)
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{
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struct gntdev_dmabuf_wait_obj *obj;
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obj = kzalloc(sizeof(*obj), GFP_KERNEL);
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if (!obj)
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return ERR_PTR(-ENOMEM);
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init_completion(&obj->completion);
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obj->gntdev_dmabuf = gntdev_dmabuf;
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mutex_lock(&priv->lock);
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list_add(&obj->next, &priv->exp_wait_list);
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/* Put our reference and wait for gntdev_dmabuf's release to fire. */
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kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
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mutex_unlock(&priv->lock);
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return obj;
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}
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static void dmabuf_exp_wait_obj_free(struct gntdev_dmabuf_priv *priv,
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struct gntdev_dmabuf_wait_obj *obj)
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{
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mutex_lock(&priv->lock);
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list_del(&obj->next);
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mutex_unlock(&priv->lock);
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kfree(obj);
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}
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static int dmabuf_exp_wait_obj_wait(struct gntdev_dmabuf_wait_obj *obj,
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u32 wait_to_ms)
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{
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if (wait_for_completion_timeout(&obj->completion,
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msecs_to_jiffies(wait_to_ms)) <= 0)
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return -ETIMEDOUT;
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return 0;
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}
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static void dmabuf_exp_wait_obj_signal(struct gntdev_dmabuf_priv *priv,
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struct gntdev_dmabuf *gntdev_dmabuf)
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{
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struct gntdev_dmabuf_wait_obj *obj;
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list_for_each_entry(obj, &priv->exp_wait_list, next)
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if (obj->gntdev_dmabuf == gntdev_dmabuf) {
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pr_debug("Found gntdev_dmabuf in the wait list, wake\n");
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complete_all(&obj->completion);
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break;
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}
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}
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static struct gntdev_dmabuf *
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dmabuf_exp_wait_obj_get_dmabuf(struct gntdev_dmabuf_priv *priv, int fd)
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{
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struct gntdev_dmabuf *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
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mutex_lock(&priv->lock);
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list_for_each_entry(gntdev_dmabuf, &priv->exp_list, next)
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if (gntdev_dmabuf->fd == fd) {
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pr_debug("Found gntdev_dmabuf in the wait list\n");
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kref_get(&gntdev_dmabuf->u.exp.refcount);
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ret = gntdev_dmabuf;
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break;
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}
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mutex_unlock(&priv->lock);
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return ret;
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}
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static int dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd,
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int wait_to_ms)
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{
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return -EINVAL;
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struct gntdev_dmabuf *gntdev_dmabuf;
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struct gntdev_dmabuf_wait_obj *obj;
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int ret;
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pr_debug("Will wait for dma-buf with fd %d\n", fd);
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/*
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* Try to find the DMA buffer: if not found means that
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* either the buffer has already been released or file descriptor
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* provided is wrong.
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*/
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gntdev_dmabuf = dmabuf_exp_wait_obj_get_dmabuf(priv, fd);
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if (IS_ERR(gntdev_dmabuf))
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return PTR_ERR(gntdev_dmabuf);
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/*
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* gntdev_dmabuf still exists and is reference count locked by us now,
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* so prepare to wait: allocate wait object and add it to the wait list,
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* so we can find it on release.
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*/
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obj = dmabuf_exp_wait_obj_new(priv, gntdev_dmabuf);
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if (IS_ERR(obj))
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return PTR_ERR(obj);
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ret = dmabuf_exp_wait_obj_wait(obj, wait_to_ms);
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dmabuf_exp_wait_obj_free(priv, obj);
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return ret;
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}
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/* DMA buffer export support. */
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static struct sg_table *
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dmabuf_pages_to_sgt(struct page **pages, unsigned int nr_pages)
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{
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struct sg_table *sgt;
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int ret;
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sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
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if (!sgt) {
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ret = -ENOMEM;
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goto out;
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}
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ret = sg_alloc_table_from_pages(sgt, pages, nr_pages, 0,
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nr_pages << PAGE_SHIFT,
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GFP_KERNEL);
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if (ret)
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goto out;
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return sgt;
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out:
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kfree(sgt);
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return ERR_PTR(ret);
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}
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static int dmabuf_exp_ops_attach(struct dma_buf *dma_buf,
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struct device *target_dev,
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struct dma_buf_attachment *attach)
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{
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struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach;
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gntdev_dmabuf_attach = kzalloc(sizeof(*gntdev_dmabuf_attach),
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GFP_KERNEL);
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if (!gntdev_dmabuf_attach)
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return -ENOMEM;
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gntdev_dmabuf_attach->dir = DMA_NONE;
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attach->priv = gntdev_dmabuf_attach;
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return 0;
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}
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static void dmabuf_exp_ops_detach(struct dma_buf *dma_buf,
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struct dma_buf_attachment *attach)
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{
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struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
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if (gntdev_dmabuf_attach) {
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struct sg_table *sgt = gntdev_dmabuf_attach->sgt;
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if (sgt) {
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if (gntdev_dmabuf_attach->dir != DMA_NONE)
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dma_unmap_sg_attrs(attach->dev, sgt->sgl,
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sgt->nents,
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gntdev_dmabuf_attach->dir,
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DMA_ATTR_SKIP_CPU_SYNC);
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sg_free_table(sgt);
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}
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kfree(sgt);
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kfree(gntdev_dmabuf_attach);
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attach->priv = NULL;
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}
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}
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static struct sg_table *
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dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach,
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enum dma_data_direction dir)
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{
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struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
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struct gntdev_dmabuf *gntdev_dmabuf = attach->dmabuf->priv;
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struct sg_table *sgt;
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pr_debug("Mapping %d pages for dev %p\n", gntdev_dmabuf->nr_pages,
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attach->dev);
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if (dir == DMA_NONE || !gntdev_dmabuf_attach)
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return ERR_PTR(-EINVAL);
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/* Return the cached mapping when possible. */
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if (gntdev_dmabuf_attach->dir == dir)
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return gntdev_dmabuf_attach->sgt;
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/*
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* Two mappings with different directions for the same attachment are
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* not allowed.
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*/
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if (gntdev_dmabuf_attach->dir != DMA_NONE)
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return ERR_PTR(-EBUSY);
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sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages,
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gntdev_dmabuf->nr_pages);
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if (!IS_ERR(sgt)) {
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if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
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DMA_ATTR_SKIP_CPU_SYNC)) {
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sg_free_table(sgt);
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kfree(sgt);
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sgt = ERR_PTR(-ENOMEM);
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} else {
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gntdev_dmabuf_attach->sgt = sgt;
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gntdev_dmabuf_attach->dir = dir;
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}
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}
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if (IS_ERR(sgt))
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pr_debug("Failed to map sg table for dev %p\n", attach->dev);
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return sgt;
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}
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static void dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment *attach,
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struct sg_table *sgt,
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enum dma_data_direction dir)
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{
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/* Not implemented. The unmap is done at dmabuf_exp_ops_detach(). */
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}
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static void dmabuf_exp_release(struct kref *kref)
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{
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struct gntdev_dmabuf *gntdev_dmabuf =
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container_of(kref, struct gntdev_dmabuf, u.exp.refcount);
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dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf);
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list_del(&gntdev_dmabuf->next);
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kfree(gntdev_dmabuf);
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}
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static void dmabuf_exp_remove_map(struct gntdev_priv *priv,
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struct gntdev_grant_map *map)
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{
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mutex_lock(&priv->lock);
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list_del(&map->next);
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gntdev_put_map(NULL /* already removed */, map);
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mutex_unlock(&priv->lock);
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}
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static void dmabuf_exp_ops_release(struct dma_buf *dma_buf)
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{
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struct gntdev_dmabuf *gntdev_dmabuf = dma_buf->priv;
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struct gntdev_dmabuf_priv *priv = gntdev_dmabuf->priv;
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dmabuf_exp_remove_map(gntdev_dmabuf->u.exp.priv,
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gntdev_dmabuf->u.exp.map);
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mutex_lock(&priv->lock);
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kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
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mutex_unlock(&priv->lock);
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}
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static void *dmabuf_exp_ops_kmap(struct dma_buf *dma_buf,
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unsigned long page_num)
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{
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/* Not implemented. */
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return NULL;
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}
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static void dmabuf_exp_ops_kunmap(struct dma_buf *dma_buf,
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unsigned long page_num, void *addr)
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{
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/* Not implemented. */
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}
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static int dmabuf_exp_ops_mmap(struct dma_buf *dma_buf,
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struct vm_area_struct *vma)
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{
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/* Not implemented. */
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return 0;
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}
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static const struct dma_buf_ops dmabuf_exp_ops = {
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.attach = dmabuf_exp_ops_attach,
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.detach = dmabuf_exp_ops_detach,
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.map_dma_buf = dmabuf_exp_ops_map_dma_buf,
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.unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
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.release = dmabuf_exp_ops_release,
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.map = dmabuf_exp_ops_kmap,
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.unmap = dmabuf_exp_ops_kunmap,
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.mmap = dmabuf_exp_ops_mmap,
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};
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struct gntdev_dmabuf_export_args {
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struct gntdev_priv *priv;
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struct gntdev_grant_map *map;
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struct gntdev_dmabuf_priv *dmabuf_priv;
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struct device *dev;
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int count;
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struct page **pages;
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u32 fd;
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};
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static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
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{
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DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
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struct gntdev_dmabuf *gntdev_dmabuf;
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int ret;
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gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
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if (!gntdev_dmabuf)
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return -ENOMEM;
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kref_init(&gntdev_dmabuf->u.exp.refcount);
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gntdev_dmabuf->priv = args->dmabuf_priv;
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gntdev_dmabuf->nr_pages = args->count;
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gntdev_dmabuf->pages = args->pages;
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gntdev_dmabuf->u.exp.priv = args->priv;
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gntdev_dmabuf->u.exp.map = args->map;
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exp_info.exp_name = KBUILD_MODNAME;
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if (args->dev->driver && args->dev->driver->owner)
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exp_info.owner = args->dev->driver->owner;
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else
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exp_info.owner = THIS_MODULE;
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exp_info.ops = &dmabuf_exp_ops;
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exp_info.size = args->count << PAGE_SHIFT;
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exp_info.flags = O_RDWR;
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exp_info.priv = gntdev_dmabuf;
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gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
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if (IS_ERR(gntdev_dmabuf->dmabuf)) {
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ret = PTR_ERR(gntdev_dmabuf->dmabuf);
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gntdev_dmabuf->dmabuf = NULL;
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goto fail;
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}
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ret = dma_buf_fd(gntdev_dmabuf->dmabuf, O_CLOEXEC);
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if (ret < 0)
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goto fail;
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gntdev_dmabuf->fd = ret;
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args->fd = ret;
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pr_debug("Exporting DMA buffer with fd %d\n", ret);
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mutex_lock(&args->dmabuf_priv->lock);
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list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
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mutex_unlock(&args->dmabuf_priv->lock);
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return 0;
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fail:
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if (gntdev_dmabuf->dmabuf)
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dma_buf_put(gntdev_dmabuf->dmabuf);
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kfree(gntdev_dmabuf);
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return ret;
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}
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static struct gntdev_grant_map *
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dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
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int count)
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{
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struct gntdev_grant_map *map;
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if (unlikely(count <= 0))
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return ERR_PTR(-EINVAL);
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if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
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(dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
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pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
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return ERR_PTR(-EINVAL);
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}
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map = gntdev_alloc_map(priv, count, dmabuf_flags);
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if (!map)
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return ERR_PTR(-ENOMEM);
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if (unlikely(gntdev_account_mapped_pages(count))) {
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pr_debug("can't map %d pages: over limit\n", count);
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gntdev_put_map(NULL, map);
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return ERR_PTR(-ENOMEM);
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}
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return map;
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}
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static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
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int count, u32 domid, u32 *refs, u32 *fd)
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{
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*fd = -1;
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return -EINVAL;
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struct gntdev_grant_map *map;
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struct gntdev_dmabuf_export_args args;
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int i, ret;
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|
||||
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. */
|
||||
@ -168,6 +614,10 @@ struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void)
|
||||
if (!priv)
|
||||
return ERR_PTR(-ENOMEM);
|
||||
|
||||
mutex_init(&priv->lock);
|
||||
INIT_LIST_HEAD(&priv->exp_list);
|
||||
INIT_LIST_HEAD(&priv->exp_wait_list);
|
||||
|
||||
return priv;
|
||||
}
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user