From: Oleksandr Andrushchenko
1. Import a dma-buf with the file descriptor provided and export
granted references to the pages of that dma-buf into the array
of grant references.
2. Add API to close all references to an imported buffer, so it can be
released by the owner. This is only valid for buffers created with
IOCTL_GNTDEV_DMABUF_IMP_TO_REFS.
Signed-off-by: Oleksandr Andrushchenko
---
drivers/xen/gntdev-dmabuf.c | 243 +++-
1 file changed, 241 insertions(+), 2 deletions(-)
diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
index f612468879b4..b5569a220f03 100644
--- a/drivers/xen/gntdev-dmabuf.c
+++ b/drivers/xen/gntdev-dmabuf.c
@@ -11,8 +11,20 @@
#include
#include
+#include
+#include
+
#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;
@@ -29,6 +41,14 @@ struct gntdev_dmabuf {
void (*release)(struct gntdev_priv *priv,
struct 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. */
@@ -53,6 +73,8 @@ struct gntdev_dmabuf_priv {
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;
};
@@ -424,21 +446,237 @@ int gntdev_dmabuf_exp_from_pages(struct
gntdev_dmabuf_export_args *args)
/* 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, _gref_head);
+ if (ret < 0) {
+ pr_err("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(_gref_head);
+ if (cur_ref < 0) {
+ ret = cur_ref;
+ pr_err("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;
+ }
+
+ ret = 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;
+
+ 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);
+ return ERR_PTR(-ENOMEM);
+}
+
struct gntdev_dmabuf *
gntdev_dmabuf_imp_to_refs(struct
