diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 823ce788b14b3e4dfd7a83821c416d60f7dabdf9..43f014cfb4585408c39972e34e1aab8c9bc2e28b 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -1,2 +1,3 @@
obj-y += grant-table.o features.o events.o
obj-y += xenbus/
+obj-$(CONFIG_XEN_XENCOMM) += xencomm.o
diff --git a/drivers/xen/xencomm.c b/drivers/xen/xencomm.c
new file mode 100644
index 0000000000000000000000000000000000000000..797cb4e31f070bbf00d42058aa7814153fe7b4ef
--- /dev/null
+++ b/drivers/xen/xencomm.c
@@ -0,0 +1,232 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (C) IBM Corp. 2006
+ *
+ * Authors: Hollis Blanchard <hollisb@us.ibm.com>
+ */
+
+#include <linux/gfp.h>
+#include <linux/mm.h>
+#include <asm/page.h>
+#include <xen/xencomm.h>
+#include <xen/interface/xen.h>
+#ifdef __ia64__
+#include <asm/xen/xencomm.h> /* for is_kern_addr() */
+#endif
+
+#ifdef HAVE_XEN_PLATFORM_COMPAT_H
+#include <xen/platform-compat.h>
+#endif
+
+static int xencomm_init(struct xencomm_desc *desc,
+ void *buffer, unsigned long bytes)
+{
+ unsigned long recorded = 0;
+ int i = 0;
+
+ while ((recorded < bytes) && (i < desc->nr_addrs)) {
+ unsigned long vaddr = (unsigned long)buffer + recorded;
+ unsigned long paddr;
+ int offset;
+ int chunksz;
+
+ offset = vaddr % PAGE_SIZE; /* handle partial pages */
+ chunksz = min(PAGE_SIZE - offset, bytes - recorded);
+
+ paddr = xencomm_vtop(vaddr);
+ if (paddr == ~0UL) {
+ printk(KERN_DEBUG "%s: couldn't translate vaddr %lx\n",
+ __func__, vaddr);
+ return -EINVAL;
+ }
+
+ desc->address[i++] = paddr;
+ recorded += chunksz;
+ }
+
+ if (recorded < bytes) {
+ printk(KERN_DEBUG
+ "%s: could only translate %ld of %ld bytes\n",
+ __func__, recorded, bytes);
+ return -ENOSPC;
+ }
+
+ /* mark remaining addresses invalid (just for safety) */
+ while (i < desc->nr_addrs)
+ desc->address[i++] = XENCOMM_INVALID;
+
+ desc->magic = XENCOMM_MAGIC;
+
+ return 0;
+}
+
+static struct xencomm_desc *xencomm_alloc(gfp_t gfp_mask,
+ void *buffer, unsigned long bytes)
+{
+ struct xencomm_desc *desc;
+ unsigned long buffer_ulong = (unsigned long)buffer;
+ unsigned long start = buffer_ulong & PAGE_MASK;
+ unsigned long end = (buffer_ulong + bytes) | ~PAGE_MASK;
+ unsigned long nr_addrs = (end - start + 1) >> PAGE_SHIFT;
+ unsigned long size = sizeof(*desc) +
+ sizeof(desc->address[0]) * nr_addrs;
+
+ /*
+ * slab allocator returns at least sizeof(void*) aligned pointer.
+ * When sizeof(*desc) > sizeof(void*), struct xencomm_desc might
+ * cross page boundary.
+ */
+ if (sizeof(*desc) > sizeof(void *)) {
+ unsigned long order = get_order(size);
+ desc = (struct xencomm_desc *)__get_free_pages(gfp_mask,
+ order);
+ if (desc == NULL)
+ return NULL;
+
+ desc->nr_addrs =
+ ((PAGE_SIZE << order) - sizeof(struct xencomm_desc)) /
+ sizeof(*desc->address);
+ } else {
+ desc = kmalloc(size, gfp_mask);
+ if (desc == NULL)
+ return NULL;
+
+ desc->nr_addrs = nr_addrs;
+ }
+ return desc;
+}
+
+void xencomm_free(struct xencomm_handle *desc)
+{
+ if (desc && !((ulong)desc & XENCOMM_INLINE_FLAG)) {
+ struct xencomm_desc *desc__ = (struct xencomm_desc *)desc;
+ if (sizeof(*desc__) > sizeof(void *)) {
+ unsigned long size = sizeof(*desc__) +
+ sizeof(desc__->address[0]) * desc__->nr_addrs;
+ unsigned long order = get_order(size);
+ free_pages((unsigned long)__va(desc), order);
+ } else
+ kfree(__va(desc));
+ }
+}
+
+static int xencomm_create(void *buffer, unsigned long bytes,
+ struct xencomm_desc **ret, gfp_t gfp_mask)
+{
+ struct xencomm_desc *desc;
+ int rc;
+
+ pr_debug("%s: %p[%ld]\n", __func__, buffer, bytes);
+
+ if (bytes == 0) {
+ /* don't create a descriptor; Xen recognizes NULL. */
+ BUG_ON(buffer != NULL);
+ *ret = NULL;
+ return 0;
+ }
+
+ BUG_ON(buffer == NULL); /* 'bytes' is non-zero */
+
+ desc = xencomm_alloc(gfp_mask, buffer, bytes);
+ if (!desc) {
+ printk(KERN_DEBUG "%s failure\n", "xencomm_alloc");
+ return -ENOMEM;
+ }
+
+ rc = xencomm_init(desc, buffer, bytes);
+ if (rc) {
+ printk(KERN_DEBUG "%s failure: %d\n", "xencomm_init", rc);
+ xencomm_free((struct xencomm_handle *)__pa(desc));
+ return rc;
+ }
+
+ *ret = desc;
+ return 0;
+}
+
+/* check if memory address is within VMALLOC region */
+static int is_phys_contiguous(unsigned long addr)
+{
+ if (!is_kernel_addr(addr))
+ return 0;
+
+ return (addr < VMALLOC_START) || (addr >= VMALLOC_END);
+}
+
+static struct xencomm_handle *xencomm_create_inline(void *ptr)
+{
+ unsigned long paddr;
+
+ BUG_ON(!is_phys_contiguous((unsigned long)ptr));
+
+ paddr = (unsigned long)xencomm_pa(ptr);
+ BUG_ON(paddr & XENCOMM_INLINE_FLAG);
+ return (struct xencomm_handle *)(paddr | XENCOMM_INLINE_FLAG);
+}
+
+/* "mini" routine, for stack-based communications: */
+static int xencomm_create_mini(void *buffer,
+ unsigned long bytes, struct xencomm_mini *xc_desc,
+ struct xencomm_desc **ret)
+{
+ int rc = 0;
+ struct xencomm_desc *desc;
+ BUG_ON(((unsigned long)xc_desc) % sizeof(*xc_desc) != 0);
+
+ desc = (void *)xc_desc;
+
+ desc->nr_addrs = XENCOMM_MINI_ADDRS;
+
+ rc = xencomm_init(desc, buffer, bytes);
+ if (!rc)
+ *ret = desc;
+
+ return rc;
+}
+
+struct xencomm_handle *xencomm_map(void *ptr, unsigned long bytes)
+{
+ int rc;
+ struct xencomm_desc *desc;
+
+ if (is_phys_contiguous((unsigned long)ptr))
+ return xencomm_create_inline(ptr);
+
+ rc = xencomm_create(ptr, bytes, &desc, GFP_KERNEL);
+
+ if (rc || desc == NULL)
+ return NULL;
+
+ return xencomm_pa(desc);
+}
+
+struct xencomm_handle *__xencomm_map_no_alloc(void *ptr, unsigned long bytes,
+ struct xencomm_mini *xc_desc)
+{
+ int rc;
+ struct xencomm_desc *desc = NULL;
+
+ if (is_phys_contiguous((unsigned long)ptr))
+ return xencomm_create_inline(ptr);
+
+ rc = xencomm_create_mini(ptr, bytes, xc_desc,
+ &desc);
+
+ if (rc)
+ return NULL;
+
+ return xencomm_pa(desc);
+}
diff --git a/include/xen/interface/xencomm.h b/include/xen/interface/xencomm.h
new file mode 100644
index 0000000000000000000000000000000000000000..ac45e0712afa09e9fa2004c48224e02e86f20fd6
--- /dev/null
+++ b/include/xen/interface/xencomm.h
@@ -0,0 +1,41 @@
+/*
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Copyright (C) IBM Corp. 2006
+ */
+
+#ifndef _XEN_XENCOMM_H_
+#define _XEN_XENCOMM_H_
+
+/* A xencomm descriptor is a scatter/gather list containing physical
+ * addresses corresponding to a virtually contiguous memory area. The
+ * hypervisor translates these physical addresses to machine addresses to copy
+ * to and from the virtually contiguous area.
+ */
+
+#define XENCOMM_MAGIC 0x58434F4D /* 'XCOM' */
+#define XENCOMM_INVALID (~0UL)
+
+struct xencomm_desc {
+ uint32_t magic;
+ uint32_t nr_addrs; /* the number of entries in address[] */
+ uint64_t address[0];
+};
+
+#endif /* _XEN_XENCOMM_H_ */
diff --git a/include/xen/xencomm.h b/include/xen/xencomm.h
new file mode 100644
index 0000000000000000000000000000000000000000..e43b039be112dc01576209ff23381b3609595707
--- /dev/null
+++ b/include/xen/xencomm.h
@@ -0,0 +1,77 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (C) IBM Corp. 2006
+ *
+ * Authors: Hollis Blanchard <hollisb@us.ibm.com>
+ * Jerone Young <jyoung5@us.ibm.com>
+ */
+
+#ifndef _LINUX_XENCOMM_H_
+#define _LINUX_XENCOMM_H_
+
+#include <xen/interface/xencomm.h>
+
+#define XENCOMM_MINI_ADDRS 3
+struct xencomm_mini {
+ struct xencomm_desc _desc;
+ uint64_t address[XENCOMM_MINI_ADDRS];
+};
+
+/* To avoid additionnal virt to phys conversion, an opaque structure is
+ presented. */
+struct xencomm_handle;
+
+extern void xencomm_free(struct xencomm_handle *desc);
+extern struct xencomm_handle *xencomm_map(void *ptr, unsigned long bytes);
+extern struct xencomm_handle *__xencomm_map_no_alloc(void *ptr,
+ unsigned long bytes, struct xencomm_mini *xc_area);
+
+#if 0
+#define XENCOMM_MINI_ALIGNED(xc_desc, n) \
+ struct xencomm_mini xc_desc ## _base[(n)] \
+ __attribute__((__aligned__(sizeof(struct xencomm_mini)))); \
+ struct xencomm_mini *xc_desc = &xc_desc ## _base[0];
+#else
+/*
+ * gcc bug workaround:
+ * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16660
+ * gcc doesn't handle properly stack variable with
+ * __attribute__((__align__(sizeof(struct xencomm_mini))))
+ */
+#define XENCOMM_MINI_ALIGNED(xc_desc, n) \
+ unsigned char xc_desc ## _base[((n) + 1 ) * \
+ sizeof(struct xencomm_mini)]; \
+ struct xencomm_mini *xc_desc = (struct xencomm_mini *) \
+ ((unsigned long)xc_desc ## _base + \
+ (sizeof(struct xencomm_mini) - \
+ ((unsigned long)xc_desc ## _base) % \
+ sizeof(struct xencomm_mini)));
+#endif
+#define xencomm_map_no_alloc(ptr, bytes) \
+ ({ XENCOMM_MINI_ALIGNED(xc_desc, 1); \
+ __xencomm_map_no_alloc(ptr, bytes, xc_desc); })
+
+/* provided by architecture code: */
+extern unsigned long xencomm_vtop(unsigned long vaddr);
+
+static inline void *xencomm_pa(void *ptr)
+{
+ return (void *)xencomm_vtop((unsigned long)ptr);
+}
+
+#define xen_guest_handle(hnd) ((hnd).p)
+
+#endif /* _LINUX_XENCOMM_H_ */