diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 858b6c0b9..908d01027 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3332,6 +3332,9 @@
 		hpmemsize=nn[KMG]	The fixed amount of bus space which is
 				reserved for hotplug bridge's memory window.
 				Default size is 2 megabytes.
+		hpmemprefsize=nn[KMG]	The fixed amount of bus space which is
+				reserved for hotplug bridge's MMIO_PREF window.
+				Default size is 2 megabytes.
 		hpbussize=nn	The minimum amount of additional bus numbers
 				reserved for buses below a hotplug bridge.
 				Default is 1.
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index c25acace7..c36c92118 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -86,9 +86,11 @@ unsigned long pci_cardbus_mem_size = DEFAULT_CARDBUS_MEM_SIZE;
 
 #define DEFAULT_HOTPLUG_IO_SIZE		(256)
 #define DEFAULT_HOTPLUG_MEM_SIZE	(2*1024*1024)
+#define DEFAULT_HOTPLUG_MEM_PREF_SIZE	(2*1024*1024)
 /* pci=hpmemsize=nnM,hpiosize=nn can override this */
 unsigned long pci_hotplug_io_size  = DEFAULT_HOTPLUG_IO_SIZE;
 unsigned long pci_hotplug_mem_size = DEFAULT_HOTPLUG_MEM_SIZE;
+unsigned long pci_hotplug_mem_pref_size = DEFAULT_HOTPLUG_MEM_PREF_SIZE;
 
 #define DEFAULT_HOTPLUG_BUS_SIZE	1
 unsigned long pci_hotplug_bus_size = DEFAULT_HOTPLUG_BUS_SIZE;
@@ -6179,6 +6181,9 @@ static int __init pci_setup(char *str)
 				pci_hotplug_io_size = memparse(str + 9, &str);
 			} else if (!strncmp(str, "hpmemsize=", 10)) {
 				pci_hotplug_mem_size = memparse(str + 10, &str);
+			} else if (!strncmp(str, "hpmemprefsize=", 14)) {
+				pci_hotplug_mem_pref_size =
+					memparse(str + 14, &str);
 			} else if (!strncmp(str, "hpbussize=", 10)) {
 				pci_hotplug_bus_size =
 					simple_strtoul(str + 10, &str, 0);
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index efe899b02..3806c9ff0 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1223,7 +1223,8 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
 {
 	struct pci_dev *dev;
 	unsigned long mask, prefmask, type2 = 0, type3 = 0;
-	resource_size_t additional_mem_size = 0, additional_io_size = 0;
+	resource_size_t additional_io_size = 0, additional_mem_size = 0,
+		additional_mem_pref_size = 0;
 	struct resource *b_res;
 	int ret;
 
@@ -1258,6 +1259,7 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
 		if (bus->self->is_hotplug_bridge) {
 			additional_io_size  = pci_hotplug_io_size;
 			additional_mem_size = pci_hotplug_mem_size;
+			additional_mem_pref_size = pci_hotplug_mem_pref_size;
 		}
 		/* Fall through */
 	default:
@@ -1274,9 +1276,9 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
 		if (b_res[2].flags & IORESOURCE_MEM_64) {
 			prefmask |= IORESOURCE_MEM_64;
 			ret = pbus_size_mem(bus, prefmask, prefmask,
-				  prefmask, prefmask,
-				  realloc_head ? 0 : additional_mem_size,
-				  additional_mem_size, realloc_head);
+				prefmask, prefmask,
+				realloc_head ? 0 : additional_mem_pref_size,
+				additional_mem_pref_size, realloc_head);
 
 			/*
 			 * If successful, all non-prefetchable resources and any
@@ -1298,9 +1300,9 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
 		if (!type2) {
 			prefmask &= ~IORESOURCE_MEM_64;
 			ret = pbus_size_mem(bus, prefmask, prefmask,
-					 prefmask, prefmask,
-					 realloc_head ? 0 : additional_mem_size,
-					 additional_mem_size, realloc_head);
+				prefmask, prefmask,
+				realloc_head ? 0 : additional_mem_pref_size,
+				additional_mem_pref_size, realloc_head);
 
 			/*
 			 * If successful, only non-prefetchable resources
@@ -1309,7 +1311,7 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
 			if (ret == 0)
 				mask = prefmask;
 			else
-				additional_mem_size += additional_mem_size;
+				additional_mem_size += additional_mem_pref_size;
 
 			type2 = type3 = IORESOURCE_MEM;
 		}
@@ -1329,8 +1331,8 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
 		 * prefetchable resource in a 64-bit prefetchable window.
 		 */
 		pbus_size_mem(bus, mask, IORESOURCE_MEM, type2, type3,
-				realloc_head ? 0 : additional_mem_size,
-				additional_mem_size, realloc_head);
+			realloc_head ? 0 : additional_mem_size,
+			additional_mem_size, realloc_head);
 		break;
 	}
 }
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 65f1d8c2f..a179856bf 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1960,6 +1960,7 @@ extern u8 pci_cache_line_size;
 
 extern unsigned long pci_hotplug_io_size;
 extern unsigned long pci_hotplug_mem_size;
+extern unsigned long pci_hotplug_mem_pref_size;
 extern unsigned long pci_hotplug_bus_size;
 
 /* Architecture-specific versions may override these (weak) */
