diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c
index de21acb62f30adbc701982bdd79ce8f069d4f7c4..642814a283eb00d269b8d9e495fc101b80899f9f 100644
--- a/arch/powerpc/platforms/powernv/vas-window.c
+++ b/arch/powerpc/platforms/powernv/vas-window.c
@@ -7,11 +7,185 @@
  * 2 of the License, or (at your option) any later version.
  */
 
+#define pr_fmt(fmt) "vas: " fmt
+
 #include <linux/types.h>
 #include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/io.h>
 
 #include "vas.h"
 
+/*
+ * Compute the paste address region for the window @window using the
+ * ->paste_base_addr and ->paste_win_id_shift we got from device tree.
+ */
+static void compute_paste_address(struct vas_window *window, u64 *addr, int *len)
+{
+	int winid;
+	u64 base, shift;
+
+	base = window->vinst->paste_base_addr;
+	shift = window->vinst->paste_win_id_shift;
+	winid = window->winid;
+
+	*addr  = base + (winid << shift);
+	if (len)
+		*len = PAGE_SIZE;
+
+	pr_debug("Txwin #%d: Paste addr 0x%llx\n", winid, *addr);
+}
+
+static inline void get_hvwc_mmio_bar(struct vas_window *window,
+			u64 *start, int *len)
+{
+	u64 pbaddr;
+
+	pbaddr = window->vinst->hvwc_bar_start;
+	*start = pbaddr + window->winid * VAS_HVWC_SIZE;
+	*len = VAS_HVWC_SIZE;
+}
+
+static inline void get_uwc_mmio_bar(struct vas_window *window,
+			u64 *start, int *len)
+{
+	u64 pbaddr;
+
+	pbaddr = window->vinst->uwc_bar_start;
+	*start = pbaddr + window->winid * VAS_UWC_SIZE;
+	*len = VAS_UWC_SIZE;
+}
+
+/*
+ * Map the paste bus address of the given send window into kernel address
+ * space. Unlike MMIO regions (map_mmio_region() below), paste region must
+ * be mapped cache-able and is only applicable to send windows.
+ */
+void *map_paste_region(struct vas_window *txwin)
+{
+	int len;
+	void *map;
+	char *name;
+	u64 start;
+
+	name = kasprintf(GFP_KERNEL, "window-v%d-w%d", txwin->vinst->vas_id,
+				txwin->winid);
+	if (!name)
+		goto free_name;
+
+	txwin->paste_addr_name = name;
+	compute_paste_address(txwin, &start, &len);
+
+	if (!request_mem_region(start, len, name)) {
+		pr_devel("%s(): request_mem_region(0x%llx, %d) failed\n",
+				__func__, start, len);
+		goto free_name;
+	}
+
+	map = ioremap_cache(start, len);
+	if (!map) {
+		pr_devel("%s(): ioremap_cache(0x%llx, %d) failed\n", __func__,
+				start, len);
+		goto free_name;
+	}
+
+	pr_devel("Mapped paste addr 0x%llx to kaddr 0x%p\n", start, map);
+	return map;
+
+free_name:
+	kfree(name);
+	return ERR_PTR(-ENOMEM);
+}
+
+
+static void *map_mmio_region(char *name, u64 start, int len)
+{
+	void *map;
+
+	if (!request_mem_region(start, len, name)) {
+		pr_devel("%s(): request_mem_region(0x%llx, %d) failed\n",
+				__func__, start, len);
+		return NULL;
+	}
+
+	map = ioremap(start, len);
+	if (!map) {
+		pr_devel("%s(): ioremap(0x%llx, %d) failed\n", __func__, start,
+				len);
+		return NULL;
+	}
+
+	return map;
+}
+
+static void unmap_region(void *addr, u64 start, int len)
+{
+	iounmap(addr);
+	release_mem_region((phys_addr_t)start, len);
+}
+
+/*
+ * Unmap the paste address region for a window.
+ */
+void unmap_paste_region(struct vas_window *window)
+{
+	int len;
+	u64 busaddr_start;
+
+	if (window->paste_kaddr) {
+		compute_paste_address(window, &busaddr_start, &len);
+		unmap_region(window->paste_kaddr, busaddr_start, len);
+		window->paste_kaddr = NULL;
+		kfree(window->paste_addr_name);
+		window->paste_addr_name = NULL;
+	}
+}
+
+/*
+ * Unmap the MMIO regions for a window.
+ */
+static void unmap_winctx_mmio_bars(struct vas_window *window)
+{
+	int len;
+	u64 busaddr_start;
+
+	if (window->hvwc_map) {
+		get_hvwc_mmio_bar(window, &busaddr_start, &len);
+		unmap_region(window->hvwc_map, busaddr_start, len);
+		window->hvwc_map = NULL;
+	}
+
+	if (window->uwc_map) {
+		get_uwc_mmio_bar(window, &busaddr_start, &len);
+		unmap_region(window->uwc_map, busaddr_start, len);
+		window->uwc_map = NULL;
+	}
+}
+
+/*
+ * Find the Hypervisor Window Context (HVWC) MMIO Base Address Region and the
+ * OS/User Window Context (UWC) MMIO Base Address Region for the given window.
+ * Map these bus addresses and save the mapped kernel addresses in @window.
+ */
+int map_winctx_mmio_bars(struct vas_window *window)
+{
+	int len;
+	u64 start;
+
+	get_hvwc_mmio_bar(window, &start, &len);
+	window->hvwc_map = map_mmio_region("HVWCM_Window", start, len);
+
+	get_uwc_mmio_bar(window, &start, &len);
+	window->uwc_map = map_mmio_region("UWCM_Window", start, len);
+
+	if (!window->hvwc_map || !window->uwc_map) {
+		unmap_winctx_mmio_bars(window);
+		return -1;
+	}
+
+	return 0;
+}
+
 /* stub for now */
 int vas_win_close(struct vas_window *window)
 {