Commit a240d6e4 authored by Oleksandr Andrushchenko's avatar Oleksandr Andrushchenko Committed by Boris Ostrovsky

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: default avatarOleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
parent 932d6562
...@@ -3,11 +3,14 @@ ...@@ -3,11 +3,14 @@
/* /*
* Xen dma-buf functionality for gntdev. * 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. * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
*/ */
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/errno.h> #include <linux/errno.h>
#include <linux/dma-buf.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/types.h> #include <linux/types.h>
#include <linux/uaccess.h> #include <linux/uaccess.h>
...@@ -18,6 +21,39 @@ ...@@ -18,6 +21,39 @@
#include "gntdev-common.h" #include "gntdev-common.h"
#include "gntdev-dmabuf.h" #include "gntdev-dmabuf.h"
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;
} 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 { struct gntdev_dmabuf_priv {
/* List of exported DMA buffers. */ /* List of exported DMA buffers. */
struct list_head exp_list; struct list_head exp_list;
...@@ -31,17 +67,427 @@ struct gntdev_dmabuf_priv { ...@@ -31,17 +67,427 @@ struct gntdev_dmabuf_priv {
/* Implementation of wait for exported DMA buffer to be released. */ /* 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, static int dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd,
int wait_to_ms) int wait_to_ms)
{ {
return -EINVAL; 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 device *target_dev,
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, static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
int count, u32 domid, u32 *refs, u32 *fd) int count, u32 domid, u32 *refs, u32 *fd)
{ {
*fd = -1; struct gntdev_grant_map *map;
return -EINVAL; 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. */ /* DMA buffer import support. */
...@@ -168,6 +614,10 @@ struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void) ...@@ -168,6 +614,10 @@ struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void)
if (!priv) if (!priv)
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
mutex_init(&priv->lock);
INIT_LIST_HEAD(&priv->exp_list);
INIT_LIST_HEAD(&priv->exp_wait_list);
return priv; return priv;
} }
......
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