[PATCH 8/8] xen/gntdev: Expose gntdev's dma-buf API for in-kernel use

From: Oleksandr Andrushchenko
Date: Fri May 25 2018 - 11:34:23 EST

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From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>

Allow creating grant device context for use by kernel modules which
require functionality, provided by gntdev. Export symbols for dma-buf
API provided by the module.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
---
drivers/xen/gntdev.c | 116 ++++++++++++++++++++++++++--------------
include/xen/grant_dev.h | 37 +++++++++++++
2 files changed, 113 insertions(+), 40 deletions(-)
create mode 100644 include/xen/grant_dev.h

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index d8b6168f2cd9..912056f3e909 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -684,14 +684,33 @@ static const struct mmu_notifier_ops gntdev_mmu_ops = {

/* ------------------------------------------------------------------ */

-static int gntdev_open(struct inode *inode, struct file *flip)
+void gntdev_free_context(struct gntdev_priv *priv)
+{
+ struct grant_map *map;
+
+ pr_debug("priv %p\n", priv);
+
+ mutex_lock(&priv->lock);
+ while (!list_empty(&priv->maps)) {
+ map = list_entry(priv->maps.next, struct grant_map, next);
+ list_del(&map->next);
+ gntdev_put_map(NULL /* already removed */, map);
+ }
+ WARN_ON(!list_empty(&priv->freeable_maps));
+
+ mutex_unlock(&priv->lock);
+
+ kfree(priv);
+}
+EXPORT_SYMBOL(gntdev_free_context);
+
+struct gntdev_priv *gntdev_alloc_context(struct device *dev)
{
struct gntdev_priv *priv;
- int ret = 0;

priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
- return -ENOMEM;
+ return ERR_PTR(-ENOMEM);

INIT_LIST_HEAD(&priv->maps);
INIT_LIST_HEAD(&priv->freeable_maps);
@@ -704,6 +723,32 @@ static int gntdev_open(struct inode *inode, struct file *flip)
INIT_LIST_HEAD(&priv->dmabuf_imp_list);
#endif

+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+ priv->dma_dev = dev;
+
+ /*
+ * The device is not spawn from a device tree, so arch_setup_dma_ops
+ * is not called, thus leaving the device with dummy DMA ops.
+ * Fix this call of_dma_configure() with a NULL node to set
+ * default DMA ops.
+ */
+ of_dma_configure(priv->dma_dev, NULL);
+#endif
+ pr_debug("priv %p\n", priv);
+
+ return priv;
+}
+EXPORT_SYMBOL(gntdev_alloc_context);
+
+static int gntdev_open(struct inode *inode, struct file *flip)
+{
+ struct gntdev_priv *priv;
+ int ret = 0;
+
+ priv = gntdev_alloc_context(gntdev_miscdev.this_device);
+ if (IS_ERR(priv))
+ return PTR_ERR(priv);
+
if (use_ptemod) {
priv->mm = get_task_mm(current);
if (!priv->mm) {
@@ -716,23 +761,11 @@ static int gntdev_open(struct inode *inode, struct file *flip)
}

if (ret) {
- kfree(priv);
+ gntdev_free_context(priv);
return ret;
}

flip->private_data = priv;
-#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
- priv->dma_dev = gntdev_miscdev.this_device;
-
- /*
- * The device is not spawn from a device tree, so arch_setup_dma_ops
- * is not called, thus leaving the device with dummy DMA ops.
- * Fix this call of_dma_configure() with a NULL node to set
- * default DMA ops.
- */
- of_dma_configure(priv->dma_dev, NULL);
-#endif
- pr_debug("priv %p\n", priv);

return 0;
}
@@ -740,22 +773,11 @@ static int gntdev_open(struct inode *inode, struct file *flip)
static int gntdev_release(struct inode *inode, struct file *flip)
{
struct gntdev_priv *priv = flip->private_data;
- struct grant_map *map;
-
- pr_debug("priv %p\n", priv);
-
- mutex_lock(&priv->lock);
- while (!list_empty(&priv->maps)) {
- map = list_entry(priv->maps.next, struct grant_map, next);
- list_del(&map->next);
- gntdev_put_map(NULL /* already removed */, map);
- }
- WARN_ON(!list_empty(&priv->freeable_maps));
- mutex_unlock(&priv->lock);

if (use_ptemod)
mmu_notifier_unregister(&priv->mn, priv->mm);
- kfree(priv);
+
+ gntdev_free_context(priv);
return 0;
}

@@ -1210,7 +1232,7 @@ dmabuf_exp_wait_obj_get_by_fd(struct gntdev_priv *priv, int fd)
return ret;
}

-static int dmabuf_exp_wait_released(struct gntdev_priv *priv, int fd,
+int gntdev_dmabuf_exp_wait_released(struct gntdev_priv *priv, int fd,
int wait_to_ms)
{
struct xen_dmabuf *xen_dmabuf;
@@ -1242,6 +1264,7 @@ static int dmabuf_exp_wait_released(struct gntdev_priv *priv, int fd,
dmabuf_exp_wait_obj_free(priv, obj);
return ret;
}
+EXPORT_SYMBOL(gntdev_dmabuf_exp_wait_released);

/* ------------------------------------------------------------------ */
/* DMA buffer export support. */
@@ -1511,7 +1534,7 @@ dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
return map;
}

-static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
+int gntdev_dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
int count, u32 domid, u32 *refs, u32 *fd)
{
struct grant_map *map;
@@ -1557,6 +1580,7 @@ static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
gntdev_remove_map(priv, map);
return ret;
}
+EXPORT_SYMBOL(gntdev_dmabuf_exp_from_refs);

/* ------------------------------------------------------------------ */
/* DMA buffer import support. */
@@ -1646,8 +1670,9 @@ static struct xen_dmabuf *dmabuf_imp_alloc_storage(int count)
return ERR_PTR(-ENOMEM);
}

-static struct xen_dmabuf *
-dmabuf_imp_to_refs(struct gntdev_priv *priv, int fd, int count, int domid)
+struct xen_dmabuf *
+gntdev_dmabuf_imp_to_refs(struct gntdev_priv *priv, int fd,
+ int count, int domid)
{
struct xen_dmabuf *xen_dmabuf, *ret;
struct dma_buf *dma_buf;
@@ -1736,6 +1761,16 @@ dmabuf_imp_to_refs(struct gntdev_priv *priv, int fd, int count, int domid)
dma_buf_put(dma_buf);
return ret;
}
+EXPORT_SYMBOL(gntdev_dmabuf_imp_to_refs);
+
+u32 *gntdev_dmabuf_imp_get_refs(struct xen_dmabuf *xen_dmabuf)
+{
+ if (xen_dmabuf)
+ return xen_dmabuf->u.imp.refs;
+
+ return NULL;
+}
+EXPORT_SYMBOL(gntdev_dmabuf_imp_get_refs);

/*
* Find the hyper dma-buf by its file descriptor and remove
@@ -1759,7 +1794,7 @@ dmabuf_imp_find_unlink(struct gntdev_priv *priv, int fd)
return ret;
}

-static int dmabuf_imp_release(struct gntdev_priv *priv, u32 fd)
+int gntdev_dmabuf_imp_release(struct gntdev_priv *priv, u32 fd)
{
struct xen_dmabuf *xen_dmabuf;
struct dma_buf_attachment *attach;
@@ -1785,6 +1820,7 @@ static int dmabuf_imp_release(struct gntdev_priv *priv, u32 fd)
dmabuf_imp_free_storage(xen_dmabuf);
return 0;
}
+EXPORT_SYMBOL(gntdev_dmabuf_imp_release);

/* ------------------------------------------------------------------ */
/* DMA buffer IOCTL support. */
@@ -1810,8 +1846,8 @@ gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv,
goto out;
}

- ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
- op.domid, refs, &op.fd);
+ ret = gntdev_dmabuf_exp_from_refs(priv, op.flags, op.count,
+ op.domid, refs, &op.fd);
if (ret)
goto out;

@@ -1832,7 +1868,7 @@ gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
if (copy_from_user(&op, u, sizeof(op)) != 0)
return -EFAULT;

- return dmabuf_exp_wait_released(priv, op.fd, op.wait_to_ms);
+ return gntdev_dmabuf_exp_wait_released(priv, op.fd, op.wait_to_ms);
}

static long
@@ -1846,7 +1882,7 @@ gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
if (copy_from_user(&op, u, sizeof(op)) != 0)
return -EFAULT;

- xen_dmabuf = dmabuf_imp_to_refs(priv, op.fd, op.count, op.domid);
+ xen_dmabuf = gntdev_dmabuf_imp_to_refs(priv, op.fd, op.count, op.domid);
if (IS_ERR(xen_dmabuf))
return PTR_ERR(xen_dmabuf);

@@ -1858,7 +1894,7 @@ gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
return 0;

out_release:
- dmabuf_imp_release(priv, op.fd);
+ gntdev_dmabuf_imp_release(priv, op.fd);
return ret;
}

@@ -1871,7 +1907,7 @@ gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
if (copy_from_user(&op, u, sizeof(op)) != 0)
return -EFAULT;

- return dmabuf_imp_release(priv, op.fd);
+ return gntdev_dmabuf_imp_release(priv, op.fd);
}
#endif

diff --git a/include/xen/grant_dev.h b/include/xen/grant_dev.h
new file mode 100644
index 000000000000..faccc9170174
--- /dev/null
+++ b/include/xen/grant_dev.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+
+/*
+ * Grant device kernel API
+ *
+ * Copyright (C) 2018 EPAM Systems Inc.
+ *
+ * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
+ */
+
+#ifndef _GRANT_DEV_H
+#define _GRANT_DEV_H
+
+#include <linux/types.h>
+
+struct device;
+struct gntdev_priv;
+#ifdef CONFIG_XEN_GNTDEV_DMABUF
+struct xen_dmabuf;
+#endif
+
+struct gntdev_priv *gntdev_alloc_context(struct device *dev);
+void gntdev_free_context(struct gntdev_priv *priv);
+
+#ifdef CONFIG_XEN_GNTDEV_DMABUF
+int gntdev_dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
+ int count, u32 domid, u32 *refs, u32 *fd);
+int gntdev_dmabuf_exp_wait_released(struct gntdev_priv *priv, int fd,
+ int wait_to_ms);
+
+struct xen_dmabuf *gntdev_dmabuf_imp_to_refs(struct gntdev_priv *priv,
+ int fd, int count, int domid);
+u32 *gntdev_dmabuf_imp_get_refs(struct xen_dmabuf *xen_dmabuf);
+int gntdev_dmabuf_imp_release(struct gntdev_priv *priv, u32 fd);
+#endif
+
+#endif
--
2.17.0

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