diff mbox

[qemu,v17,11/12] spapr_pci/spapr_pci_vfio: Support Dynamic DMA Windows (DDW)

Message ID 201606010902.u518ww0O029350@mx0a-001b2d01.pphosted.com
State New
Headers show

Commit Message

Alexey Kardashevskiy June 1, 2016, 8:57 a.m. UTC
This adds support for Dynamic DMA Windows (DDW) option defined by
the SPAPR specification which allows to have additional DMA window(s)

The "ddw" property is enabled by default on a PHB but for compatibility
the pseries-2.5 machine (TODO: update version) and older disable it.
This also creates a single DMA window for the older machines to
maintain backward migration.

This implements DDW for PHB with emulated and VFIO devices. The host
kernel support is required. The advertised IOMMU page sizes are 4K and
64K; 16M pages are supported but not advertised by default, in order to
enable them, the user has to specify "pgsz" property for PHB and
enable huge pages for RAM.

The existing linux guests try creating one additional huge DMA window
with 64K or 16MB pages and map the entire guest RAM to. If succeeded,
the guest switches to dma_direct_ops and never calls TCE hypercalls
(H_PUT_TCE,...) again. This enables VFIO devices to use the entire RAM
and not waste time on map/unmap later. This adds a "dma64_win_addr"
property which is a bus address for the 64bit window and by default
set to 0x800.0000.0000.0000 as this is what the modern POWER8 hardware
uses and this allows having emulated and VFIO devices on the same bus.

This adds 4 RTAS handlers:
* ibm,query-pe-dma-window
* ibm,create-pe-dma-window
* ibm,remove-pe-dma-window
* ibm,reset-pe-dma-window
These are registered from type_init() callback.

These RTAS handlers are implemented in a separate file to avoid polluting
spapr_iommu.c with PCI.

This changes sPAPRPHBState::dma_liobn to an array to allow 2 LIOBNs.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v17:
* fixed: "query" did return non-page-shifted value when memory hotplug is enabled

v16:
* s/dma_liobn/dma_liobn[SPAPR_PCI_DMA_MAX_WINDOWS]/
* s/SPAPR_PCI_LIOBN()/dma_liobn[]/

v15:
* moved page mask filtering to PHB realize(), use "-mempath" to know
if there are huge pages
* fixed error reporting in RTAS handlers
* max window size accounts now hotpluggable memory boundaries
---
 hw/ppc/Makefile.objs        |   1 +
 hw/ppc/spapr.c              |   5 +
 hw/ppc/spapr_pci.c          |  77 +++++++++---
 hw/ppc/spapr_rtas_ddw.c     | 293 ++++++++++++++++++++++++++++++++++++++++++++
 include/hw/pci-host/spapr.h |   8 +-
 include/hw/ppc/spapr.h      |  16 ++-
 trace-events                |   4 +
 7 files changed, 383 insertions(+), 21 deletions(-)
 create mode 100644 hw/ppc/spapr_rtas_ddw.c
diff mbox

Patch

diff --git a/hw/ppc/Makefile.objs b/hw/ppc/Makefile.objs
index c1ffc77..986b36f 100644
--- a/hw/ppc/Makefile.objs
+++ b/hw/ppc/Makefile.objs
@@ -7,6 +7,7 @@  obj-$(CONFIG_PSERIES) += spapr_pci.o spapr_rtc.o spapr_drc.o spapr_rng.o
 ifeq ($(CONFIG_PCI)$(CONFIG_PSERIES)$(CONFIG_LINUX), yyy)
 obj-y += spapr_pci_vfio.o
 endif
+obj-$(CONFIG_PSERIES) += spapr_rtas_ddw.o
 # PowerPC 4xx boards
 obj-y += ppc405_boards.o ppc4xx_devs.o ppc405_uc.o ppc440_bamboo.o
 obj-y += ppc4xx_pci.o
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 44e401a..6ddcda9 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2366,6 +2366,11 @@  DEFINE_SPAPR_MACHINE(2_6, "2.6", true);
         .driver   = "spapr-vlan", \
         .property = "use-rx-buffer-pools", \
         .value    = "off", \
+    }, \
+    {\
+        .driver   = TYPE_SPAPR_PCI_HOST_BRIDGE,\
+        .property = "ddw",\
+        .value    = stringify(off),\
     },
 
 static void spapr_machine_2_5_instance_options(MachineState *machine)
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 68de523..bcf0360 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -35,6 +35,7 @@ 
 #include "hw/ppc/spapr.h"
 #include "hw/pci-host/spapr.h"
 #include "exec/address-spaces.h"
+#include "exec/ram_addr.h"
 #include <libfdt.h>
 #include "trace.h"
 #include "qemu/error-report.h"
@@ -45,6 +46,7 @@ 
 #include "hw/ppc/spapr_drc.h"
 #include "sysemu/device_tree.h"
 #include "sysemu/kvm.h"
+#include "sysemu/hostmem.h"
 
 #include "hw/vfio/vfio.h"
 
@@ -1088,7 +1090,7 @@  static void spapr_phb_add_pci_device(sPAPRDRConnector *drc,
     int fdt_start_offset = 0, fdt_size;
 
     if (object_dynamic_cast(OBJECT(pdev), "vfio-pci")) {
-        sPAPRTCETable *tcet = spapr_tce_find_by_liobn(phb->dma_liobn);
+        sPAPRTCETable *tcet = spapr_tce_find_by_liobn(phb->dma_liobn[0]);
 
         spapr_tce_set_need_vfio(tcet, true);
     }
@@ -1310,11 +1312,14 @@  static void spapr_phb_realize(DeviceState *dev, Error **errp)
     PCIBus *bus;
     uint64_t msi_window_size = 4096;
     sPAPRTCETable *tcet;
+    const unsigned windows_supported =
+        sphb->ddw_enabled ? SPAPR_PCI_DMA_MAX_WINDOWS : 1;
 
     if (sphb->index != (uint32_t)-1) {
         hwaddr windows_base;
 
-        if ((sphb->buid != (uint64_t)-1) || (sphb->dma_liobn != (uint32_t)-1)
+        if ((sphb->buid != (uint64_t)-1) || (sphb->dma_liobn[0] != (uint32_t)-1)
+            || ((sphb->dma_liobn[1] != (uint32_t)-1) && (windows_supported > 1))
             || (sphb->mem_win_addr != (hwaddr)-1)
             || (sphb->io_win_addr != (hwaddr)-1)) {
             error_setg(errp, "Either \"index\" or other parameters must"
@@ -1329,7 +1334,9 @@  static void spapr_phb_realize(DeviceState *dev, Error **errp)
         }
 
         sphb->buid = SPAPR_PCI_BASE_BUID + sphb->index;
-        sphb->dma_liobn = SPAPR_PCI_LIOBN(sphb->index, 0);
+        for (i = 0; i < windows_supported; ++i) {
+            sphb->dma_liobn[i] = SPAPR_PCI_LIOBN(sphb->index, i);
+        }
 
         windows_base = SPAPR_PCI_WINDOW_BASE
             + sphb->index * SPAPR_PCI_WINDOW_SPACING;
@@ -1342,8 +1349,9 @@  static void spapr_phb_realize(DeviceState *dev, Error **errp)
         return;
     }
 
-    if (sphb->dma_liobn == (uint32_t)-1) {
-        error_setg(errp, "LIOBN not specified for PHB");
+    if ((sphb->dma_liobn[0] == (uint32_t)-1) ||
+        ((sphb->dma_liobn[1] == (uint32_t)-1) && (windows_supported > 1))) {
+        error_setg(errp, "LIOBN(s) not specified for PHB");
         return;
     }
 
@@ -1461,16 +1469,18 @@  static void spapr_phb_realize(DeviceState *dev, Error **errp)
         }
     }
 
-    tcet = spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn);
-    if (!tcet) {
-        error_setg(errp, "Unable to create TCE table for %s",
-                   sphb->dtbusname);
-        return;
+    /* DMA setup */
+    for (i = 0; i < windows_supported; ++i) {
+        tcet = spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn[i]);
+        if (!tcet) {
+            error_setg(errp, "Creating window#%d failed for %s",
+                       i, sphb->dtbusname);
+            return;
+        }
+        memory_region_add_subregion_overlap(&sphb->iommu_root, 0,
+                                            spapr_tce_get_iommu(tcet), 0);
     }
 
-    memory_region_add_subregion_overlap(&sphb->iommu_root, 0,
-                                        spapr_tce_get_iommu(tcet), 0);
-
     sphb->msi = g_hash_table_new_full(g_int_hash, g_int_equal, g_free, g_free);
 }
 
@@ -1487,13 +1497,19 @@  static int spapr_phb_children_reset(Object *child, void *opaque)
 
 void spapr_phb_dma_reset(sPAPRPHBState *sphb)
 {
-    sPAPRTCETable *tcet = spapr_tce_find_by_liobn(sphb->dma_liobn);
+    int i;
+    sPAPRTCETable *tcet;
 
-    if (tcet && tcet->nb_table) {
-        spapr_tce_table_disable(tcet);
+    for (i = 0; i < SPAPR_PCI_DMA_MAX_WINDOWS; ++i) {
+        tcet = spapr_tce_find_by_liobn(sphb->dma_liobn[i]);
+
+        if (tcet && tcet->nb_table) {
+            spapr_tce_table_disable(tcet);
+        }
     }
 
     /* Register default 32bit DMA window */
+    tcet = spapr_tce_find_by_liobn(sphb->dma_liobn[0]);
     spapr_tce_table_enable(tcet, SPAPR_TCE_PAGE_SHIFT, sphb->dma_win_addr,
                            sphb->dma_win_size >> SPAPR_TCE_PAGE_SHIFT);
 }
@@ -1515,7 +1531,8 @@  static void spapr_phb_reset(DeviceState *qdev)
 static Property spapr_phb_properties[] = {
     DEFINE_PROP_UINT32("index", sPAPRPHBState, index, -1),
     DEFINE_PROP_UINT64("buid", sPAPRPHBState, buid, -1),
-    DEFINE_PROP_UINT32("liobn", sPAPRPHBState, dma_liobn, -1),
+    DEFINE_PROP_UINT32("liobn", sPAPRPHBState, dma_liobn[0], -1),
+    DEFINE_PROP_UINT32("liobn64", sPAPRPHBState, dma_liobn[1], -1),
     DEFINE_PROP_UINT64("mem_win_addr", sPAPRPHBState, mem_win_addr, -1),
     DEFINE_PROP_UINT64("mem_win_size", sPAPRPHBState, mem_win_size,
                        SPAPR_PCI_MMIO_WIN_SIZE),
@@ -1527,6 +1544,11 @@  static Property spapr_phb_properties[] = {
     /* Default DMA window is 0..1GB */
     DEFINE_PROP_UINT64("dma_win_addr", sPAPRPHBState, dma_win_addr, 0),
     DEFINE_PROP_UINT64("dma_win_size", sPAPRPHBState, dma_win_size, 0x40000000),
+    DEFINE_PROP_UINT64("dma64_win_addr", sPAPRPHBState, dma64_window_addr,
+                       0x800000000000000ULL),
+    DEFINE_PROP_BOOL("ddw", sPAPRPHBState, ddw_enabled, true),
+    DEFINE_PROP_UINT64("pgsz", sPAPRPHBState, page_size_mask,
+                       (1ULL << 12) | (1ULL << 16)),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -1603,7 +1625,7 @@  static const VMStateDescription vmstate_spapr_pci = {
     .post_load = spapr_pci_post_load,
     .fields = (VMStateField[]) {
         VMSTATE_UINT64_EQUAL(buid, sPAPRPHBState),
-        VMSTATE_UINT32_EQUAL(dma_liobn, sPAPRPHBState),
+        VMSTATE_UNUSED(4), /* dma_liobn */
         VMSTATE_UINT64_EQUAL(mem_win_addr, sPAPRPHBState),
         VMSTATE_UINT64_EQUAL(mem_win_size, sPAPRPHBState),
         VMSTATE_UINT64_EQUAL(io_win_addr, sPAPRPHBState),
@@ -1780,6 +1802,15 @@  int spapr_populate_pci_dt(sPAPRPHBState *phb,
     uint32_t interrupt_map_mask[] = {
         cpu_to_be32(b_ddddd(-1)|b_fff(0)), 0x0, 0x0, cpu_to_be32(-1)};
     uint32_t interrupt_map[PCI_SLOT_MAX * PCI_NUM_PINS][7];
+    uint32_t ddw_applicable[] = {
+        cpu_to_be32(RTAS_IBM_QUERY_PE_DMA_WINDOW),
+        cpu_to_be32(RTAS_IBM_CREATE_PE_DMA_WINDOW),
+        cpu_to_be32(RTAS_IBM_REMOVE_PE_DMA_WINDOW)
+    };
+    uint32_t ddw_extensions[] = {
+        cpu_to_be32(1),
+        cpu_to_be32(RTAS_IBM_RESET_PE_DMA_WINDOW)
+    };
     sPAPRTCETable *tcet;
     PCIBus *bus = PCI_HOST_BRIDGE(phb)->bus;
     sPAPRFDT s_fdt;
@@ -1804,6 +1835,14 @@  int spapr_populate_pci_dt(sPAPRPHBState *phb,
     _FDT(fdt_setprop_cell(fdt, bus_off, "ibm,pci-config-space-type", 0x1));
     _FDT(fdt_setprop_cell(fdt, bus_off, "ibm,pe-total-#msi", XICS_IRQS));
 
+    /* Dynamic DMA window */
+    if (phb->ddw_enabled) {
+        _FDT(fdt_setprop(fdt, bus_off, "ibm,ddw-applicable", &ddw_applicable,
+                         sizeof(ddw_applicable)));
+        _FDT(fdt_setprop(fdt, bus_off, "ibm,ddw-extensions",
+                         &ddw_extensions, sizeof(ddw_extensions)));
+    }
+
     /* Build the interrupt-map, this must matches what is done
      * in pci_spapr_map_irq
      */
@@ -1827,7 +1866,7 @@  int spapr_populate_pci_dt(sPAPRPHBState *phb,
     _FDT(fdt_setprop(fdt, bus_off, "interrupt-map", &interrupt_map,
                      sizeof(interrupt_map)));
 
-    tcet = spapr_tce_find_by_liobn(phb->dma_liobn);
+    tcet = spapr_tce_find_by_liobn(phb->dma_liobn[0]);
     if (!tcet) {
         return -1;
     }
diff --git a/hw/ppc/spapr_rtas_ddw.c b/hw/ppc/spapr_rtas_ddw.c
new file mode 100644
index 0000000..17bbae0
--- /dev/null
+++ b/hw/ppc/spapr_rtas_ddw.c
@@ -0,0 +1,293 @@ 
+/*
+ * QEMU sPAPR Dynamic DMA windows support
+ *
+ * Copyright (c) 2015 Alexey Kardashevskiy, IBM Corporation.
+ *
+ *  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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "cpu.h"
+#include "qemu/error-report.h"
+#include "hw/ppc/spapr.h"
+#include "hw/pci-host/spapr.h"
+#include "trace.h"
+
+static int spapr_phb_get_active_win_num_cb(Object *child, void *opaque)
+{
+    sPAPRTCETable *tcet;
+
+    tcet = (sPAPRTCETable *) object_dynamic_cast(child, TYPE_SPAPR_TCE_TABLE);
+    if (tcet && tcet->nb_table) {
+        ++*(unsigned *)opaque;
+    }
+    return 0;
+}
+
+static unsigned spapr_phb_get_active_win_num(sPAPRPHBState *sphb)
+{
+    unsigned ret = 0;
+
+    object_child_foreach(OBJECT(sphb), spapr_phb_get_active_win_num_cb, &ret);
+
+    return ret;
+}
+
+static int spapr_phb_get_free_liobn_cb(Object *child, void *opaque)
+{
+    sPAPRTCETable *tcet;
+
+    tcet = (sPAPRTCETable *) object_dynamic_cast(child, TYPE_SPAPR_TCE_TABLE);
+    if (tcet && !tcet->nb_table) {
+        *(uint32_t *)opaque = tcet->liobn;
+        return 1;
+    }
+    return 0;
+}
+
+static unsigned spapr_phb_get_free_liobn(sPAPRPHBState *sphb)
+{
+    uint32_t liobn = 0;
+
+    object_child_foreach(OBJECT(sphb), spapr_phb_get_free_liobn_cb, &liobn);
+
+    return liobn;
+}
+
+static uint32_t spapr_page_mask_to_query_mask(uint64_t page_mask)
+{
+    int i;
+    uint32_t mask = 0;
+    const struct { int shift; uint32_t mask; } masks[] = {
+        { 12, RTAS_DDW_PGSIZE_4K },
+        { 16, RTAS_DDW_PGSIZE_64K },
+        { 24, RTAS_DDW_PGSIZE_16M },
+        { 25, RTAS_DDW_PGSIZE_32M },
+        { 26, RTAS_DDW_PGSIZE_64M },
+        { 27, RTAS_DDW_PGSIZE_128M },
+        { 28, RTAS_DDW_PGSIZE_256M },
+        { 34, RTAS_DDW_PGSIZE_16G },
+    };
+
+    for (i = 0; i < ARRAY_SIZE(masks); ++i) {
+        if (page_mask & (1ULL << masks[i].shift)) {
+            mask |= masks[i].mask;
+        }
+    }
+
+    return mask;
+}
+
+static void rtas_ibm_query_pe_dma_window(PowerPCCPU *cpu,
+                                         sPAPRMachineState *spapr,
+                                         uint32_t token, uint32_t nargs,
+                                         target_ulong args,
+                                         uint32_t nret, target_ulong rets)
+{
+    sPAPRPHBState *sphb;
+    uint64_t buid, max_window_size;
+    uint32_t avail, addr, pgmask = 0;
+    MachineState *machine = MACHINE(spapr);
+
+    if ((nargs != 3) || (nret != 5)) {
+        goto param_error_exit;
+    }
+
+    buid = ((uint64_t)rtas_ld(args, 1) << 32) | rtas_ld(args, 2);
+    addr = rtas_ld(args, 0);
+    sphb = spapr_pci_find_phb(spapr, buid);
+    if (!sphb || !sphb->ddw_enabled) {
+        goto param_error_exit;
+    }
+
+    /* Translate page mask to LoPAPR format */
+    pgmask = spapr_page_mask_to_query_mask(sphb->page_size_mask);
+
+    /*
+     * This is "Largest contiguous block of TCEs allocated specifically
+     * for (that is, are reserved for) this PE".
+     * Return the maximum number as maximum supported RAM size was in 4K pages.
+     */
+    if (machine->ram_size == machine->maxram_size) {
+        max_window_size = machine->ram_size;
+    } else {
+        MemoryHotplugState *hpms = &spapr->hotplug_memory;
+
+        max_window_size = hpms->base + memory_region_size(&hpms->mr);
+    }
+
+    avail = SPAPR_PCI_DMA_MAX_WINDOWS - spapr_phb_get_active_win_num(sphb);
+
+    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
+    rtas_st(rets, 1, avail);
+    rtas_st(rets, 2, max_window_size >> SPAPR_TCE_PAGE_SHIFT);
+    rtas_st(rets, 3, pgmask);
+    rtas_st(rets, 4, 0); /* DMA migration mask, not supported */
+
+    trace_spapr_iommu_ddw_query(buid, addr, avail, max_window_size, pgmask);
+    return;
+
+param_error_exit:
+    rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
+}
+
+static void rtas_ibm_create_pe_dma_window(PowerPCCPU *cpu,
+                                          sPAPRMachineState *spapr,
+                                          uint32_t token, uint32_t nargs,
+                                          target_ulong args,
+                                          uint32_t nret, target_ulong rets)
+{
+    sPAPRPHBState *sphb;
+    sPAPRTCETable *tcet = NULL;
+    uint32_t addr, page_shift, window_shift, liobn;
+    uint64_t buid;
+
+    if ((nargs != 5) || (nret != 4)) {
+        goto param_error_exit;
+    }
+
+    buid = ((uint64_t)rtas_ld(args, 1) << 32) | rtas_ld(args, 2);
+    addr = rtas_ld(args, 0);
+    sphb = spapr_pci_find_phb(spapr, buid);
+    if (!sphb || !sphb->ddw_enabled) {
+        goto param_error_exit;
+    }
+
+    page_shift = rtas_ld(args, 3);
+    window_shift = rtas_ld(args, 4);
+    liobn = spapr_phb_get_free_liobn(sphb);
+
+    if (!(sphb->page_size_mask & (1ULL << page_shift)) ||
+        (window_shift < page_shift)) {
+        goto param_error_exit;
+    }
+
+    if (!liobn || !sphb->ddw_enabled ||
+        spapr_phb_get_active_win_num(sphb) == SPAPR_PCI_DMA_MAX_WINDOWS) {
+        goto hw_error_exit;
+    }
+
+    tcet = spapr_tce_find_by_liobn(liobn);
+    trace_spapr_iommu_ddw_create(buid, addr, 1ULL << page_shift,
+                                 1ULL << window_shift,
+                                 tcet ? tcet->bus_offset : 0xbaadf00d, liobn);
+    if (!tcet) {
+        goto hw_error_exit;
+    }
+
+    spapr_tce_table_enable(tcet, page_shift, sphb->dma64_window_addr,
+                           1ULL << (window_shift - page_shift));
+    if (!tcet->nb_table) {
+        goto hw_error_exit;
+    }
+
+    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
+    rtas_st(rets, 1, liobn);
+    rtas_st(rets, 2, tcet->bus_offset >> 32);
+    rtas_st(rets, 3, tcet->bus_offset & ((uint32_t) -1));
+
+    return;
+
+hw_error_exit:
+    rtas_st(rets, 0, RTAS_OUT_HW_ERROR);
+    return;
+
+param_error_exit:
+    rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
+}
+
+static void rtas_ibm_remove_pe_dma_window(PowerPCCPU *cpu,
+                                          sPAPRMachineState *spapr,
+                                          uint32_t token, uint32_t nargs,
+                                          target_ulong args,
+                                          uint32_t nret, target_ulong rets)
+{
+    sPAPRPHBState *sphb;
+    sPAPRTCETable *tcet;
+    uint32_t liobn;
+
+    if ((nargs != 1) || (nret != 1)) {
+        goto param_error_exit;
+    }
+
+    liobn = rtas_ld(args, 0);
+    tcet = spapr_tce_find_by_liobn(liobn);
+    if (!tcet) {
+        goto param_error_exit;
+    }
+
+    sphb = SPAPR_PCI_HOST_BRIDGE(OBJECT(tcet)->parent);
+    if (!sphb || !sphb->ddw_enabled || !tcet->nb_table) {
+        goto param_error_exit;
+    }
+
+    spapr_tce_table_disable(tcet);
+    trace_spapr_iommu_ddw_remove(liobn);
+
+    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
+    return;
+
+param_error_exit:
+    rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
+}
+
+static void rtas_ibm_reset_pe_dma_window(PowerPCCPU *cpu,
+                                         sPAPRMachineState *spapr,
+                                         uint32_t token, uint32_t nargs,
+                                         target_ulong args,
+                                         uint32_t nret, target_ulong rets)
+{
+    sPAPRPHBState *sphb;
+    uint64_t buid;
+    uint32_t addr;
+
+    if ((nargs != 3) || (nret != 1)) {
+        goto param_error_exit;
+    }
+
+    buid = ((uint64_t)rtas_ld(args, 1) << 32) | rtas_ld(args, 2);
+    addr = rtas_ld(args, 0);
+    sphb = spapr_pci_find_phb(spapr, buid);
+    if (!sphb || !sphb->ddw_enabled) {
+        goto param_error_exit;
+    }
+
+    spapr_phb_dma_reset(sphb);
+    trace_spapr_iommu_ddw_reset(buid, addr);
+
+    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
+
+    return;
+
+param_error_exit:
+    rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
+}
+
+static void spapr_rtas_ddw_init(void)
+{
+    spapr_rtas_register(RTAS_IBM_QUERY_PE_DMA_WINDOW,
+                        "ibm,query-pe-dma-window",
+                        rtas_ibm_query_pe_dma_window);
+    spapr_rtas_register(RTAS_IBM_CREATE_PE_DMA_WINDOW,
+                        "ibm,create-pe-dma-window",
+                        rtas_ibm_create_pe_dma_window);
+    spapr_rtas_register(RTAS_IBM_REMOVE_PE_DMA_WINDOW,
+                        "ibm,remove-pe-dma-window",
+                        rtas_ibm_remove_pe_dma_window);
+    spapr_rtas_register(RTAS_IBM_RESET_PE_DMA_WINDOW,
+                        "ibm,reset-pe-dma-window",
+                        rtas_ibm_reset_pe_dma_window);
+}
+
+type_init(spapr_rtas_ddw_init)
diff --git a/include/hw/pci-host/spapr.h b/include/hw/pci-host/spapr.h
index 7848366..36a370e 100644
--- a/include/hw/pci-host/spapr.h
+++ b/include/hw/pci-host/spapr.h
@@ -32,6 +32,8 @@ 
 #define SPAPR_PCI_HOST_BRIDGE(obj) \
     OBJECT_CHECK(sPAPRPHBState, (obj), TYPE_SPAPR_PCI_HOST_BRIDGE)
 
+#define SPAPR_PCI_DMA_MAX_WINDOWS    2
+
 typedef struct sPAPRPHBState sPAPRPHBState;
 
 typedef struct spapr_pci_msi {
@@ -56,7 +58,7 @@  struct sPAPRPHBState {
     hwaddr mem_win_addr, mem_win_size, io_win_addr, io_win_size;
     MemoryRegion memwindow, iowindow, msiwindow;
 
-    uint32_t dma_liobn;
+    uint32_t dma_liobn[SPAPR_PCI_DMA_MAX_WINDOWS];
     hwaddr dma_win_addr, dma_win_size;
     AddressSpace iommu_as;
     MemoryRegion iommu_root;
@@ -71,6 +73,10 @@  struct sPAPRPHBState {
     spapr_pci_msi_mig *msi_devs;
 
     QLIST_ENTRY(sPAPRPHBState) list;
+
+    bool ddw_enabled;
+    uint64_t page_size_mask;
+    uint64_t dma64_window_addr;
 };
 
 #define SPAPR_PCI_MAX_INDEX          255
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 971df3d..59fad22 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -412,6 +412,16 @@  int spapr_allocate_irq_block(int num, bool lsi, bool msi);
 #define RTAS_OUT_NOT_AUTHORIZED                 -9002
 #define RTAS_OUT_SYSPARM_PARAM_ERROR            -9999
 
+/* DDW pagesize mask values from ibm,query-pe-dma-window */
+#define RTAS_DDW_PGSIZE_4K       0x01
+#define RTAS_DDW_PGSIZE_64K      0x02
+#define RTAS_DDW_PGSIZE_16M      0x04
+#define RTAS_DDW_PGSIZE_32M      0x08
+#define RTAS_DDW_PGSIZE_64M      0x10
+#define RTAS_DDW_PGSIZE_128M     0x20
+#define RTAS_DDW_PGSIZE_256M     0x40
+#define RTAS_DDW_PGSIZE_16G      0x80
+
 /* RTAS tokens */
 #define RTAS_TOKEN_BASE      0x2000
 
@@ -453,8 +463,12 @@  int spapr_allocate_irq_block(int num, bool lsi, bool msi);
 #define RTAS_IBM_SET_SLOT_RESET                 (RTAS_TOKEN_BASE + 0x23)
 #define RTAS_IBM_CONFIGURE_PE                   (RTAS_TOKEN_BASE + 0x24)
 #define RTAS_IBM_SLOT_ERROR_DETAIL              (RTAS_TOKEN_BASE + 0x25)
+#define RTAS_IBM_QUERY_PE_DMA_WINDOW            (RTAS_TOKEN_BASE + 0x26)
+#define RTAS_IBM_CREATE_PE_DMA_WINDOW           (RTAS_TOKEN_BASE + 0x27)
+#define RTAS_IBM_REMOVE_PE_DMA_WINDOW           (RTAS_TOKEN_BASE + 0x28)
+#define RTAS_IBM_RESET_PE_DMA_WINDOW            (RTAS_TOKEN_BASE + 0x29)
 
-#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x26)
+#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2A)
 
 /* RTAS ibm,get-system-parameter token values */
 #define RTAS_SYSPARM_SPLPAR_CHARACTERISTICS      20
diff --git a/trace-events b/trace-events
index ec32c20..dec80e4 100644
--- a/trace-events
+++ b/trace-events
@@ -1433,6 +1433,10 @@  spapr_iommu_xlate(uint64_t liobn, uint64_t ioba, uint64_t tce, unsigned perm, un
 spapr_iommu_new_table(uint64_t liobn, void *table, int fd) "liobn=%"PRIx64" table=%p fd=%d"
 spapr_iommu_pre_save(uint64_t liobn, uint32_t nb, uint64_t offs, uint32_t ps) "liobn=%"PRIx64" %"PRIx32" bus_offset=%"PRIx64" ps=%"PRIu32
 spapr_iommu_post_load(uint64_t liobn, uint32_t pre_nb, uint32_t post_nb, uint64_t offs, uint32_t ps) "liobn=%"PRIx64" %"PRIx32" => %"PRIx32" bus_offset=%"PRIx64" ps=%"PRIu32
+spapr_iommu_ddw_query(uint64_t buid, uint32_t cfgaddr, unsigned wa, uint64_t win_size, uint32_t pgmask) "buid=%"PRIx64" addr=%"PRIx32", %u windows available, max window size=%"PRIx64", mask=%"PRIx32
+spapr_iommu_ddw_create(uint64_t buid, uint32_t cfgaddr, uint64_t pg_size, uint64_t req_size, uint64_t start, uint32_t liobn) "buid=%"PRIx64" addr=%"PRIx32", page size=0x%"PRIx64", requested=0x%"PRIx64", start addr=%"PRIx64", liobn=%"PRIx32
+spapr_iommu_ddw_remove(uint32_t liobn) "liobn=%"PRIx32
+spapr_iommu_ddw_reset(uint64_t buid, uint32_t cfgaddr) "buid=%"PRIx64" addr=%"PRIx32
 
 # hw/ppc/ppc.c
 ppc_tb_adjust(uint64_t offs1, uint64_t offs2, int64_t diff, int64_t seconds) "adjusted from 0x%"PRIx64" to 0x%"PRIx64", diff %"PRId64" (%"PRId64"s)"