Re: [PATCH 5/8] xen/gntdev: Add initial support for dma-buf UAPI

2018-05-30 Thread Boris Ostrovsky 
On 05/25/2018 11:33 AM, Oleksandr Andrushchenko wrote:

>  
> +/*
> + * Create a dma-buf [1] from grant references @refs of count @count provided
> + * by the foreign domain @domid with flags @flags.
> + *
> + * By default dma-buf is backed by system memory pages, but by providing
> + * one of the GNTDEV_DMA_FLAG_XXX flags it can also be created as
> + * a DMA write-combine or coherent buffer, e.g. allocated with dma_alloc_wc/
> + * dma_alloc_coherent.
> + *
> + * Returns 0 if dma-buf was successfully created and the corresponding
> + * dma-buf's file descriptor is returned in @fd.
> + *
> + * [1] 
> https://elixir.bootlin.com/linux/latest/source/Documentation/driver-api/dma-buf.rst


Documentation/driver-api/dma-buf.rst.


-boris
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Re: [PATCH 5/8] xen/gntdev: Add initial support for dma-buf UAPI

2018-05-30 Thread Oleksandr Andrushchenko 

On 05/30/2018 01:34 AM, Boris Ostrovsky wrote:

On 05/25/2018 11:33 AM, Oleksandr Andrushchenko wrote:

  
+/*

+ * Create a dma-buf [1] from grant references @refs of count @count provided
+ * by the foreign domain @domid with flags @flags.
+ *
+ * By default dma-buf is backed by system memory pages, but by providing
+ * one of the GNTDEV_DMA_FLAG_XXX flags it can also be created as
+ * a DMA write-combine or coherent buffer, e.g. allocated with dma_alloc_wc/
+ * dma_alloc_coherent.
+ *
+ * Returns 0 if dma-buf was successfully created and the corresponding
+ * dma-buf's file descriptor is returned in @fd.
+ *
+ * [1] 
https://elixir.bootlin.com/linux/latest/source/Documentation/driver-api/dma-buf.rst


Documentation/driver-api/dma-buf.rst.


Indeed ;)

-boris

Thank you,
Oleksandr
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Re: [PATCH 5/8] xen/gntdev: Add initial support for dma-buf UAPI

2018-05-30 Thread Oleksandr Andrushchenko 

On 05/25/2018 06:33 PM, Oleksandr Andrushchenko wrote:

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 3431fe210624..eaf63a2c7ae6 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -152,6 +152,16 @@ config XEN_GNTDEV
help
  Allows userspace processes to use grants.
  
+config XEN_GNTDEV_DMABUF

+   bool "Add support for dma-buf grant access device driver extension"
+   depends on XEN_GNTDEV && XEN_GRANT_DMA_ALLOC
This must be "depends on XEN_GNTDEV && XEN_GRANT_DMA_ALLOC && 
*DMA_SHARED_BUFFER*"

+   help
+ Allows userspace processes and kernel modules to use Xen backed
+ dma-buf implementation. With this extension grant references to
+ the pages of an imported dma-buf can be exported for other domain
+ use and grant references coming from a foreign domain can be
+ converted into a local dma-buf for local export.
+



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[PATCH 5/8] xen/gntdev: Add initial support for dma-buf UAPI

2018-05-25 Thread Oleksandr Andrushchenko 
From: Oleksandr Andrushchenko 

Add UAPI and IOCTLs for dma-buf grant device driver extension:
the extension allows userspace processes and kernel modules to
use Xen backed dma-buf implementation. With this extension grant
references to the pages of an imported dma-buf can be exported
for other domain use and grant references coming from a foreign
domain can be converted into a local dma-buf for local export.
Implement basic initialization and stubs for Xen DMA buffers'
support.

Signed-off-by: Oleksandr Andrushchenko 
---
 drivers/xen/Kconfig   |  10 +++
 drivers/xen/gntdev.c  | 148 ++
 include/uapi/xen/gntdev.h |  91 +++
 3 files changed, 249 insertions(+)

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 3431fe210624..eaf63a2c7ae6 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -152,6 +152,16 @@ config XEN_GNTDEV
help
  Allows userspace processes to use grants.
 
+config XEN_GNTDEV_DMABUF
+   bool "Add support for dma-buf grant access device driver extension"
+   depends on XEN_GNTDEV && XEN_GRANT_DMA_ALLOC
+   help
+ Allows userspace processes and kernel modules to use Xen backed
+ dma-buf implementation. With this extension grant references to
+ the pages of an imported dma-buf can be exported for other domain
+ use and grant references coming from a foreign domain can be
+ converted into a local dma-buf for local export.
+
 config XEN_GRANT_DEV_ALLOC
tristate "User-space grant reference allocator driver"
depends on XEN
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 640a579f42ea..9e450622af1a 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -6,6 +6,7 @@
  *
  * Copyright (c) 2006-2007, D G Murray.
  *   (c) 2009 Gerd Hoffmann 
+ *   (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -122,6 +123,17 @@ struct grant_map {
 #endif
 };
 
+#ifdef CONFIG_XEN_GNTDEV_DMABUF
+struct xen_dmabuf {
+   union {
+   struct {
+   /* Granted references of the imported buffer. */
+   grant_ref_t *refs;
+   } imp;
+   } u;
+};
+#endif
+
 static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
 
 static struct miscdevice gntdev_miscdev;
@@ -1036,6 +1048,128 @@ static long gntdev_ioctl_grant_copy(struct gntdev_priv 
*priv, void __user *u)
return ret;
 }
 
+#ifdef CONFIG_XEN_GNTDEV_DMABUF
+/* -- */
+/* DMA buffer export support. */
+/* -- */
+
+static int dmabuf_exp_wait_released(struct gntdev_priv *priv, int fd,
+   int wait_to_ms)
+{
+   return -ETIMEDOUT;
+}
+
+static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
+   int count, u32 domid, u32 *refs, u32 *fd)
+{
+   *fd = -1;
+   return -EINVAL;
+}
+
+/* -- */
+/* DMA buffer import support. */
+/* -- */
+
+static int dmabuf_imp_release(struct gntdev_priv *priv, u32 fd)
+{
+   return 0;
+}
+
+static struct xen_dmabuf *
+dmabuf_imp_to_refs(struct gntdev_priv *priv, int fd, int count, int domid)
+{
+   return ERR_PTR(-ENOMEM);
+}
+
+/* -- */
+/* DMA buffer IOCTL support.  */
+/* -- */
+
+static long
+gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv,
+ struct ioctl_gntdev_dmabuf_exp_from_refs 
__user *u)
+{
+   struct ioctl_gntdev_dmabuf_exp_from_refs op;
+   u32 *refs;
+   long ret;
+
+   if (copy_from_user(, u, sizeof(op)) != 0)
+   return -EFAULT;
+
+   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, );
+   if (ret)
+   goto out;
+
+   if (copy_to_user(u, , sizeof(op)) != 0)
+   ret = -EFAULT;
+
+out:
+   kfree(refs);
+   return ret;
+}
+
+static long
+gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
+