diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 8c001c1..a251054 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -59,6 +59,7 @@
 #include "qapi/visitor.h"
 #include "standard-headers/linux/input.h"
 #include "hw/arm/smmuv3.h"
+#include "hw/acpi/acpi.h"
 
 #define DEFINE_VIRT_MACHINE_LATEST(major, minor, latest) \
     static void virt_##major##_##minor##_class_init(ObjectClass *oc, \
@@ -94,34 +95,25 @@
 
 #define PLATFORM_BUS_NUM_IRQS 64
 
-/* RAM limit in GB. Since VIRT_MEM starts at the 1GB mark, this means
- * RAM can go up to the 256GB mark, leaving 256GB of the physical
- * address space unallocated and free for future use between 256G and 512G.
- * If we need to provide more RAM to VMs in the future then we need to:
- *  * allocate a second bank of RAM starting at 2TB and working up
- *  * fix the DT and ACPI table generation code in QEMU to correctly
- *    report two split lumps of RAM to the guest
- *  * fix KVM in the host kernel to allow guests with >40 bit address spaces
- * (We don't want to fill all the way up to 512GB with RAM because
- * we might want it for non-RAM purposes later. Conversely it seems
- * reasonable to assume that anybody configuring a VM with a quarter
- * of a terabyte of RAM will be doing it on a host with more than a
- * terabyte of physical address space.)
- */
-#define RAMLIMIT_GB 255
-#define RAMLIMIT_BYTES (RAMLIMIT_GB * 1024ULL * 1024 * 1024)
+#define SZ_64K 0x10000
+#define SZ_1G (1024ULL * 1024 * 1024)
 
 /* Addresses and sizes of our components.
- * 0..128MB is space for a flash device so we can run bootrom code such as UEFI.
- * 128MB..256MB is used for miscellaneous device I/O.
- * 256MB..1GB is reserved for possible future PCI support (ie where the
- * PCI memory window will go if we add a PCI host controller).
- * 1GB and up is RAM (which may happily spill over into the
- * high memory region beyond 4GB).
- * This represents a compromise between how much RAM can be given to
- * a 32 bit VM and leaving space for expansion and in particular for PCI.
- * Note that devices should generally be placed at multiples of 0x10000,
+ * 0..128MB is space for a flash device so we can run bootrom code such as UEFI,
+ * 128MB..256MB is used for miscellaneous device I/O,
+ * 256MB..1GB is used for PCI host controller,
+ * 1GB..256GB is RAM (not hotpluggable),
+ * 256GB..512GB: is left for device I/O (non RAM purpose),
+ * 512GB..1TB: high mem PCI MMIO region,
+ * 2TB..4TB is used for hot-pluggable DIMM (assumes 42b GPA is supported).
+ *
+ * Note that IO devices should generally be placed at multiples of 0x10000,
  * to accommodate guests using 64K pages.
+ *
+ * Conversely it seems reasonable to assume that anybody configuring a VM
+ * with a quarter of a terabyte of RAM will be doing it on a host with more
+ * than a terabyte of physical address space.)
+ *
  */
 static const MemMapEntry a15memmap[] = {
     /* Space up to 0x8000000 is reserved for a boot ROM */
@@ -148,9 +140,11 @@ static const MemMapEntry a15memmap[] = {
     [VIRT_PCIE_MMIO] =          { 0x10000000, 0x2eff0000 },
     [VIRT_PCIE_PIO] =           { 0x3eff0000, 0x00010000 },
     [VIRT_PCIE_ECAM] =          { 0x3f000000, 0x01000000 },
-    [VIRT_MEM] =                { 0x40000000, RAMLIMIT_BYTES },
+    /* 255GB RAM */
+    [VIRT_MEM] =                { SZ_1G , 255 * SZ_1G },
     /* Second PCIe window, 512GB wide at the 512GB boundary */
-    [VIRT_PCIE_MMIO_HIGH] =   { 0x8000000000ULL, 0x8000000000ULL },
+    [VIRT_PCIE_MMIO_HIGH] =     { 512 * SZ_1G, 512 * SZ_1G },
+    [VIRT_HOTPLUG_MEM] =        { 2048 * SZ_1G, 2048 * SZ_1G },
 };
 
 static const int a15irqmap[] = {
@@ -1166,6 +1160,58 @@ static void create_secure_ram(VirtMachineState *vms,
     g_free(nodename);
 }
 
+static void create_device_memory(VirtMachineState *vms, MemoryRegion *sysmem)
+{
+    MachineState *ms = MACHINE(vms);
+    uint64_t device_memory_size;
+    uint64_t align = SZ_64K;
+
+    /* always allocate the device memory information */
+    ms->device_memory = g_malloc0(sizeof(*ms->device_memory));
+
+    if (vms->max_vm_phys_shift < 42) {
+        /* device memory starts at 2TB whereas this VM supports less than
+         * 2TB GPA */
+        if (ms->maxram_size > ms->ram_size || ms->ram_slots) {
+            MachineClass *mc = MACHINE_GET_CLASS(ms);
+
+            error_report("\"-memory 'slots|maxmem'\" is not supported by %s "
+                         "since KVM does not support more than 41b IPA",
+                         mc->name);
+            exit(EXIT_FAILURE);
+        }
+        return;
+    }
+
+    if (ms->ram_slots > ACPI_MAX_RAM_SLOTS) {
+        error_report("unsupported number of memory slots: %"PRIu64,
+                     ms->ram_slots);
+        exit(EXIT_FAILURE);
+    }
+
+    if (QEMU_ALIGN_UP(ms->maxram_size, align) != ms->maxram_size) {
+        error_report("maximum memory size must be aligned to multiple of 0x%"
+                     PRIx64, align);
+            exit(EXIT_FAILURE);
+    }
+
+    ms->device_memory->base = vms->memmap[VIRT_HOTPLUG_MEM].base;
+    device_memory_size = ms->maxram_size - ms->ram_size;
+
+    if (device_memory_size > vms->memmap[VIRT_HOTPLUG_MEM].size) {
+        error_report("unsupported amount of maximum memory: " RAM_ADDR_FMT,
+                         ms->maxram_size);
+        exit(EXIT_FAILURE);
+    }
+
+    memory_region_init(&ms->device_memory->mr, OBJECT(vms),
+                       "device-memory", device_memory_size);
+    memory_region_add_subregion(sysmem, ms->device_memory->base,
+                                &ms->device_memory->mr);
+    vms->bootinfo.device_memory_start = ms->device_memory->base;
+    vms->bootinfo.device_memory_size = device_memory_size;
+}
+
 static void *machvirt_dtb(const struct arm_boot_info *binfo, int *fdt_size)
 {
     const VirtMachineState *board = container_of(binfo, VirtMachineState,
@@ -1371,7 +1417,8 @@ static void machvirt_init(MachineState *machine)
     vms->smp_cpus = smp_cpus;
 
     if (machine->ram_size > vms->memmap[VIRT_MEM].size) {
-        error_report("mach-virt: cannot model more than %dGB RAM", RAMLIMIT_GB);
+        error_report("mach-virt: cannot model more than %dGB RAM",
+                     (int)(vms->memmap[VIRT_MEM].size / SZ_1G));
         exit(1);
     }
 
@@ -1464,6 +1511,8 @@ static void machvirt_init(MachineState *machine)
                                          machine->ram_size);
     memory_region_add_subregion(sysmem, vms->memmap[VIRT_MEM].base, ram);
 
+    create_device_memory(vms, sysmem);
+
     create_flash(vms, sysmem, secure_sysmem ? secure_sysmem : sysmem);
 
     create_gic(vms, pic);
diff --git a/include/hw/arm/arm.h b/include/hw/arm/arm.h
index ffed392..76269e6 100644
--- a/include/hw/arm/arm.h
+++ b/include/hw/arm/arm.h
@@ -116,6 +116,8 @@ struct arm_boot_info {
     bool secure_board_setup;
 
     arm_endianness endianness;
+    hwaddr device_memory_start;
+    hwaddr device_memory_size;
 };
 
 /**
diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index 600d96d..3b0c765 100644
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -74,6 +74,7 @@ enum {
     VIRT_GPIO,
     VIRT_SECURE_UART,
     VIRT_SECURE_MEM,
+    VIRT_HOTPLUG_MEM,
 };
 
 typedef enum VirtIOMMUType {
