diff --git a/Makefile.target b/Makefile.target
index e15b1c4..e5817ab 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -218,7 +218,7 @@ obj-i386-y += cirrus_vga.o apic.o ioapic.o piix_pci.o
 obj-i386-y += vmmouse.o vmport.o hpet.o applesmc.o
 obj-i386-y += device-hotplug.o pci-hotplug.o smbios.o wdt_ib700.o
 obj-i386-y += debugcon.o multiboot.o
-obj-i386-y += pc_piix.o
+obj-i386-y += pc_piix.o dma_rw.o
 obj-i386-$(CONFIG_SPICE) += qxl.o qxl-logger.o qxl-render.o
 
 # shared objects
diff --git a/hw/dma_rw.c b/hw/dma_rw.c
new file mode 100644
index 0000000..ef8e7f8
--- /dev/null
+++ b/hw/dma_rw.c
@@ -0,0 +1,124 @@
+/*
+ * Generic DMA memory access interface.
+ *
+ * Copyright (c) 2011 Eduard - Gabriel Munteanu
+ *
+ * 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.
+ */
+
+#include "dma_rw.h"
+#include "range.h"
+
+static void dma_register_memory_map(DMADevice *dev,
+                                    dma_addr_t addr,
+                                    dma_addr_t len,
+                                    target_phys_addr_t paddr,
+                                    DMAInvalidateMapFunc *invalidate,
+                                    void *invalidate_opaque)
+{
+    DMAMemoryMap *map;
+
+    map = qemu_malloc(sizeof(DMAMemoryMap));
+    map->addr               = addr;
+    map->len                = len;
+    map->paddr              = paddr;
+    map->invalidate         = invalidate;
+    map->invalidate_opaque  = invalidate_opaque;
+
+    QLIST_INSERT_HEAD(&dev->mmu->memory_maps, map, list);
+}
+
+static void dma_unregister_memory_map(DMADevice *dev,
+                                      target_phys_addr_t paddr,
+                                      dma_addr_t len)
+{
+    DMAMemoryMap *map;
+
+    QLIST_FOREACH(map, &dev->mmu->memory_maps, list) {
+        if (map->paddr == paddr && map->len == len) {
+            QLIST_REMOVE(map, list);
+            free(map);
+        }
+    }
+}
+
+void dma_invalidate_memory_range(DMADevice *dev,
+                                 dma_addr_t addr,
+                                 dma_addr_t len)
+{
+    DMAMemoryMap *map;
+
+    QLIST_FOREACH(map, &dev->mmu->memory_maps, list) {
+        if (ranges_overlap(addr, len, map->addr, map->len)) {
+            map->invalidate(map->invalidate_opaque);
+            QLIST_REMOVE(map, list);
+            free(map);
+        }
+    }
+}
+
+void *dma_memory_map(DMADevice *dev,
+                     DMAInvalidateMapFunc *cb,
+                     void *opaque,
+                     dma_addr_t addr,
+                     dma_addr_t *len,
+                     int is_write)
+{
+    int err;
+    target_phys_addr_t paddr, plen;
+
+    if (!dev || !dev->mmu) {
+        return cpu_physical_memory_map(addr, len, is_write);
+    }
+
+    plen = *len;
+    err = dev->mmu->translate(dev, addr, &paddr, &plen, is_write);
+    if (err) {
+        return NULL;
+    }
+
+    /*
+     * If this is true, the virtual region is contiguous,
+     * but the translated physical region isn't. We just
+     * clamp *len, much like cpu_physical_memory_map() does.
+     */
+    if (plen < *len) {
+        *len = plen;
+    }
+
+    /* We treat maps as remote TLBs to cope with stuff like AIO. */
+    if (cb) {
+        dma_register_memory_map(dev, addr, *len, paddr, cb, opaque);
+    }
+
+    return cpu_physical_memory_map(paddr, len, is_write);
+}
+
+void dma_memory_unmap(DMADevice *dev,
+                      void *buffer,
+                      dma_addr_t len,
+                      int is_write,
+                      dma_addr_t access_len)
+{
+    cpu_physical_memory_unmap(buffer, len, is_write, access_len);
+    if (dev && dev->mmu) {
+        dma_unregister_memory_map(dev, (target_phys_addr_t) buffer, len);
+    }
+}
+
diff --git a/hw/dma_rw.h b/hw/dma_rw.h
new file mode 100644
index 0000000..bc93511
--- /dev/null
+++ b/hw/dma_rw.h
@@ -0,0 +1,157 @@
+#ifndef DMA_RW_H
+#define DMA_RW_H
+
+#include "qemu-common.h"
+
+typedef uint64_t dma_addr_t;
+
+typedef struct DMAMmu DMAMmu;
+typedef struct DMADevice DMADevice;
+typedef struct DMAMemoryMap DMAMemoryMap;
+
+typedef int DMATranslateFunc(DMADevice *dev,
+                             dma_addr_t addr,
+                             dma_addr_t *paddr,
+                             dma_addr_t *len,
+                             int is_write);
+
+typedef void DMAInvalidateMapFunc(void *);
+
+struct DMAMmu {
+    DeviceState *iommu;
+    DMATranslateFunc *translate;
+    QLIST_HEAD(memory_maps, DMAMemoryMap) memory_maps;
+};
+
+struct DMADevice {
+    DMAMmu *mmu;
+};
+
+struct DMAMemoryMap {
+    dma_addr_t              addr;
+    dma_addr_t              len;
+    target_phys_addr_t      paddr;
+    DMAInvalidateMapFunc    *invalidate;
+    void                    *invalidate_opaque;
+
+    QLIST_ENTRY(DMAMemoryMap) list;
+};
+
+static inline void dma_memory_rw(DMADevice *dev,
+                                 dma_addr_t addr,
+                                 void *buf,
+                                 dma_addr_t len,
+                                 int is_write)
+{
+    dma_addr_t paddr, plen;
+    int err;
+
+    /*
+     * Fast-path non-iommu.
+     * More importantly, makes it obvious what this function does.
+     */
+    if (!dev || !dev->mmu) {
+        cpu_physical_memory_rw(addr, buf, plen, is_write);
+        return;
+    }
+
+    while (len) {
+        err = dev->mmu->translate(dev, addr, &paddr, &plen, is_write);
+        if (err) {
+            return;
+        }
+
+        /* The translation might be valid for larger regions. */
+        if (plen > len) {
+            plen = len;
+        }
+
+        cpu_physical_memory_rw(paddr, buf, plen, is_write);
+
+        len -= plen;
+        addr += plen;
+        buf += plen;
+    }
+}
+
+static inline void dma_memory_read(DMADevice *dev,
+                                   dma_addr_t addr,
+                                   void *buf,
+                                   dma_addr_t len)
+{
+    dma_memory_rw(dev, addr, buf, len, 0);
+}
+
+static inline void dma_memory_write(DMADevice *dev,
+                                    dma_addr_t addr,
+                                    const void *buf,
+                                    dma_addr_t len)
+{
+    dma_memory_rw(dev, addr, (void *) buf, len, 1);
+}
+
+void *dma_memory_map(DMADevice *dev,
+                     DMAInvalidateMapFunc *cb,
+                     void *opaque,
+                     dma_addr_t addr,
+                     dma_addr_t *len,
+                     int is_write);
+void dma_memory_unmap(DMADevice *dev,
+                      void *buffer,
+                      dma_addr_t len,
+                      int is_write,
+                      dma_addr_t access_len);
+
+
+void dma_invalidate_memory_range(DMADevice *dev,
+                                 dma_addr_t addr,
+                                 dma_addr_t len);
+
+
+#define DEFINE_DMA_LD(suffix, size)                                       \
+static inline uint##size##_t                                              \
+dma_ld##suffix(DMADevice *dev, dma_addr_t addr)                           \
+{                                                                         \
+    int err;                                                              \
+    dma_addr_t paddr, plen;                                               \
+                                                                          \
+    if (!dev || !dev->mmu) {                                              \
+        return ld##suffix##_phys(addr);                                   \
+    }                                                                     \
+                                                                          \
+    err = dev->mmu->translate(dev, addr, &paddr, &plen, 0);               \
+    if (err || (plen < size / 8))                                         \
+        return 0;                                                         \
+                                                                          \
+    return ld##suffix##_phys(paddr);                                      \
+}
+
+#define DEFINE_DMA_ST(suffix, size)                                       \
+static inline void                                                        \
+dma_st##suffix(DMADevice *dev, dma_addr_t addr, uint##size##_t val)       \
+{                                                                         \
+    int err;                                                              \
+    target_phys_addr_t paddr, plen;                                       \
+                                                                          \
+    if (!dev || !dev->mmu) {                                              \
+        st##suffix##_phys(addr, val);                                     \
+        return;                                                           \
+    }                                                                     \
+    err = dev->mmu->translate(dev, addr, &paddr, &plen, 1);               \
+    if (err || (plen < size / 8))                                         \
+        return;                                                           \
+                                                                          \
+    st##suffix##_phys(paddr, val);                                        \
+}
+
+DEFINE_DMA_LD(ub, 8)
+DEFINE_DMA_LD(uw, 16)
+DEFINE_DMA_LD(l, 32)
+DEFINE_DMA_LD(q, 64)
+
+DEFINE_DMA_ST(b, 8)
+DEFINE_DMA_ST(w, 16)
+DEFINE_DMA_ST(l, 32)
+DEFINE_DMA_ST(q, 64)
+
+#endif
