xen-gntalloc: Userspace grant allocation driver
This allows a userspace application to allocate a shared page for
implementing inter-domain communication or device drivers. These
shared pages can be mapped using the gntdev device or by the kernel
in another domain.
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/include/xen/gntalloc.h b/include/xen/gntalloc.h
new file mode 100644
index 0000000..bc3b85e
--- /dev/null
+++ b/include/xen/gntalloc.h
@@ -0,0 +1,50 @@
+/******************************************************************************
+ * gntalloc.h
+ *
+ * Interface to /dev/xen/gntalloc.
+ *
+ * Author: Daniel De Graaf <dgdegra@tycho.nsa.gov>
+ *
+ * This file is in the public domain.
+ */
+
+#ifndef __LINUX_PUBLIC_GNTALLOC_H__
+#define __LINUX_PUBLIC_GNTALLOC_H__
+
+/*
+ * Allocates a new page and creates a new grant reference.
+ */
+#define IOCTL_GNTALLOC_ALLOC_GREF \
+_IOC(_IOC_NONE, 'G', 5, sizeof(struct ioctl_gntalloc_alloc_gref))
+struct ioctl_gntalloc_alloc_gref {
+ /* IN parameters */
+ /* The ID of the domain to be given access to the grants. */
+ uint16_t domid;
+ /* Flags for this mapping */
+ uint16_t flags;
+ /* Number of pages to map */
+ uint32_t count;
+ /* OUT parameters */
+ /* The offset to be used on a subsequent call to mmap(). */
+ uint64_t index;
+ /* The grant references of the newly created grant, one per page */
+ /* Variable size, depending on count */
+ uint32_t gref_ids[1];
+};
+
+#define GNTALLOC_FLAG_WRITABLE 1
+
+/*
+ * Deallocates the grant reference, allowing the associated page to be freed if
+ * no other domains are using it.
+ */
+#define IOCTL_GNTALLOC_DEALLOC_GREF \
+_IOC(_IOC_NONE, 'G', 6, sizeof(struct ioctl_gntalloc_dealloc_gref))
+struct ioctl_gntalloc_dealloc_gref {
+ /* IN parameters */
+ /* The offset returned in the map operation */
+ uint64_t index;
+ /* Number of references to unmap */
+ uint32_t count;
+};
+#endif /* __LINUX_PUBLIC_GNTALLOC_H__ */