Re: [Qemu-block] [PATCH for 2.8 02/11] virtio: convert to use DMA api

2016-09-05 Thread Wei Xu 

On 2016年08月30日 11:06, Jason Wang wrote:

@@ -1587,6 +1595,11 @@ static void virtio_pci_device_plugged(DeviceState *d, 
Error **errp)
  }

  if (legacy) {
+if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) {
+error_setg(errp, "VIRTIO_F_IOMMU_PLATFORM was supported by"
+   "neither legacy nor transitional device.");
+return ;
+}


Not sure if i understand it correctly, the transitional device here 
maybe a bit hard to understand, just a tip for your convenience,
besides the denied prompt, can we add what kind of device is supported 
to the message? such as modern device only, like this.


"VIRTIO_F_IOMMU_PLATFORM is supported by modern device only, it
is not supported by either legacy or transitional device."


  /* legacy and transitional */
  pci_set_word(config + PCI_SUBSYSTEM_VENDOR_ID,
   pci_get_word(config + PCI_VENDOR_ID));

Re: [Qemu-block] [PATCH for 2.8 02/11] virtio: convert to use DMA api

2016-09-04 Thread Michael S. Tsirkin 
On Tue, Aug 30, 2016 at 11:06:50AM +0800, Jason Wang wrote:
> @@ -1587,6 +1595,11 @@ static void virtio_pci_device_plugged(DeviceState *d, 
> Error **errp)
>  }
>  
>  if (legacy) {
> +if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) {
> +error_setg(errp, "VIRTIO_F_IOMMU_PLATFORM was supported by"
> +   "neither legacy nor transitional device.");
> +return ;
> +}
>  /* legacy and transitional */
>  pci_set_word(config + PCI_SUBSYSTEM_VENDOR_ID,
>   pci_get_word(config + PCI_VENDOR_ID));


We probably should have code to fail init if modern is disabled
since the configuration is inconsistent.

But I do not think we should break transitional devices
with this flag.


> @@ -2452,6 +2465,7 @@ static void virtio_pci_bus_class_init(ObjectClass 
> *klass, void *data)
>  k->ioeventfd_disabled = virtio_pci_ioeventfd_disabled;
>  k->ioeventfd_set_disabled = virtio_pci_ioeventfd_set_disabled;
>  k->ioeventfd_assign = virtio_pci_ioeventfd_assign;
> +k->get_dma_as = virtio_pci_get_dma_as;
>  }
>  
>  static const TypeInfo virtio_pci_bus_info = {
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 15ee3a7..99ea97c 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -23,6 +23,7 @@
>  #include "hw/virtio/virtio-bus.h"
>  #include "migration/migration.h"
>  #include "hw/virtio/virtio-access.h"
> +#include "sysemu/dma.h"
>  
>  /*
>   * The alignment to use between consumer and producer parts of vring.
> @@ -122,7 +123,7 @@ void virtio_queue_update_rings(VirtIODevice *vdev, int n)
>  static void vring_desc_read(VirtIODevice *vdev, VRingDesc *desc,
>  hwaddr desc_pa, int i)
>  {
> -address_space_read(_space_memory, desc_pa + i * 
> sizeof(VRingDesc),
> +address_space_read(virtio_get_dma_as(vdev), desc_pa + i * 
> sizeof(VRingDesc),
> MEMTXATTRS_UNSPECIFIED, (void *)desc, 
> sizeof(VRingDesc));
>  virtio_tswap64s(vdev, >addr);
>  virtio_tswap32s(vdev, >len);
> @@ -164,7 +165,7 @@ static inline void vring_used_write(VirtQueue *vq, 
> VRingUsedElem *uelem,
>  virtio_tswap32s(vq->vdev, >id);
>  virtio_tswap32s(vq->vdev, >len);
>  pa = vq->vring.used + offsetof(VRingUsed, ring[i]);
> -address_space_write(_space_memory, pa, MEMTXATTRS_UNSPECIFIED,
> +address_space_write(virtio_get_dma_as(vq->vdev), pa, 
> MEMTXATTRS_UNSPECIFIED,
> (void *)uelem, sizeof(VRingUsedElem));
>  }
>  
> @@ -244,6 +245,7 @@ int virtio_queue_empty(VirtQueue *vq)
>  static void virtqueue_unmap_sg(VirtQueue *vq, const VirtQueueElement *elem,
> unsigned int len)
>  {
> +AddressSpace *dma_as = virtio_get_dma_as(vq->vdev);
>  unsigned int offset;
>  int i;
>  
> @@ -251,17 +253,17 @@ static void virtqueue_unmap_sg(VirtQueue *vq, const 
> VirtQueueElement *elem,
>  for (i = 0; i < elem->in_num; i++) {
>  size_t size = MIN(len - offset, elem->in_sg[i].iov_len);
>  
> -cpu_physical_memory_unmap(elem->in_sg[i].iov_base,
> -  elem->in_sg[i].iov_len,
> -  1, size);
> +dma_memory_unmap(dma_as, elem->in_sg[i].iov_base, 
> elem->in_sg[i].iov_len,
> + DMA_DIRECTION_FROM_DEVICE, size);
>  
>  offset += size;
>  }
>  
>  for (i = 0; i < elem->out_num; i++)
> -cpu_physical_memory_unmap(elem->out_sg[i].iov_base,
> -  elem->out_sg[i].iov_len,
> -  0, elem->out_sg[i].iov_len);
> +dma_memory_unmap(dma_as, elem->out_sg[i].iov_base,
> + elem->out_sg[i].iov_len,
> + DMA_DIRECTION_TO_DEVICE,
> + elem->out_sg[i].iov_len);
>  }
>  
>  void virtqueue_discard(VirtQueue *vq, const VirtQueueElement *elem,
> @@ -451,7 +453,8 @@ int virtqueue_avail_bytes(VirtQueue *vq, unsigned int 
> in_bytes,
>  return in_bytes <= in_total && out_bytes <= out_total;
>  }
>  
> -static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct 
> iovec *iov,
> +static void virtqueue_map_desc(VirtIODevice *vdev,
> +   unsigned int *p_num_sg, hwaddr *addr, struct 
> iovec *iov,
> unsigned int max_num_sg, bool is_write,
> hwaddr pa, size_t sz)
>  {
> @@ -471,7 +474,10 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, 
> hwaddr *addr, struct iove
>  exit(1);
>  }
>  
> -iov[num_sg].iov_base = cpu_physical_memory_map(pa, , is_write);
> +iov[num_sg].iov_base = dma_memory_map(virtio_get_dma_as(vdev), pa, 
> ,
> +  is_write ?
> +  DMA_DIRECTION_FROM_DEVICE:
> +

Re: [Qemu-block] [PATCH for 2.8 02/11] virtio: convert to use DMA api

2016-08-30 Thread Jason Wang 



On 2016年08月30日 15:31, Cornelia Huck wrote:

On Tue, 30 Aug 2016 11:06:50 +0800
Jason Wang  wrote:


Currently, all virtio devices bypass IOMMU completely. This is because
address_space_memory is assumed and used during DMA emulation. This
patch converts the virtio core API to use DMA API. This idea is

- introducing a new transport specific helper to query the dma address
   space. (only pci version is implemented).
- query and use this address space during virtio device guest memory
   accessing when iommu platform (VIRTIO_F_IOMMU_PLATFORM) was enabled
   for this device.

Cc: Michael S. Tsirkin 
Cc: Stefan Hajnoczi 
Cc: Kevin Wolf 
Cc: Amit Shah 
Cc: Paolo Bonzini 
Cc: qemu-block@nongnu.org
Signed-off-by: Jason Wang 
---
  hw/block/virtio-blk.c |  2 +-
  hw/char/virtio-serial-bus.c   |  3 +-
  hw/scsi/virtio-scsi.c |  4 ++-
  hw/virtio/virtio-pci.c| 14 +
  hw/virtio/virtio.c| 62 ---
  include/hw/virtio/virtio-access.h | 43 ---
  include/hw/virtio/virtio-bus.h|  1 +
  include/hw/virtio/virtio.h|  8 +++--
  8 files changed, 98 insertions(+), 39 deletions(-)

diff --git a/include/hw/virtio/virtio-access.h 
b/include/hw/virtio/virtio-access.h
index 440b455..4071dad 100644
--- a/include/hw/virtio/virtio-access.h
+++ b/include/hw/virtio/virtio-access.h
@@ -17,12 +17,25 @@
  #define QEMU_VIRTIO_ACCESS_H

  #include "hw/virtio/virtio.h"
+#include "hw/virtio/virtio-bus.h"
  #include "exec/address-spaces.h"

  #if defined(TARGET_PPC64) || defined(TARGET_ARM)
  #define LEGACY_VIRTIO_IS_BIENDIAN 1
  #endif

+static inline AddressSpace *virtio_get_dma_as(VirtIODevice *vdev)
+{
+BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
+VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+
+if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM) &&
+k->get_dma_as) {
+return k->get_dma_as(qbus->parent);
+}
+return _space_memory;
+}

One thing I'm a bit worried about is that we're introducing a check
even if we know that the device will never support
VIRTIO_F_IOMMU_PLATFORM (i.e. virtio-ccw). The qom incantations will
add cycles to any invocation of this.

Is the address space likely to change during device lifetime? Can we
cache it in some way?



I think so, we can cache it in vdev and set it during features set.

Then we can avoid qom stuffs during data path.

Re: [Qemu-block] [PATCH for 2.8 02/11] virtio: convert to use DMA api

2016-08-30 Thread Michael S. Tsirkin 
On Tue, Aug 30, 2016 at 01:02:14PM +0300, Michael S. Tsirkin wrote:
> On Tue, Aug 30, 2016 at 09:31:27AM +0200, Cornelia Huck wrote:
> > On Tue, 30 Aug 2016 11:06:50 +0800
> > Jason Wang  wrote:
> > 
> > > Currently, all virtio devices bypass IOMMU completely. This is because
> > > address_space_memory is assumed and used during DMA emulation. This
> > > patch converts the virtio core API to use DMA API. This idea is
> > > 
> > > - introducing a new transport specific helper to query the dma address
> > >   space. (only pci version is implemented).
> > > - query and use this address space during virtio device guest memory
> > >   accessing when iommu platform (VIRTIO_F_IOMMU_PLATFORM) was enabled
> > >   for this device.
> > > 
> > > Cc: Michael S. Tsirkin 
> > > Cc: Stefan Hajnoczi 
> > > Cc: Kevin Wolf 
> > > Cc: Amit Shah 
> > > Cc: Paolo Bonzini 
> > > Cc: qemu-block@nongnu.org
> > > Signed-off-by: Jason Wang 
> > > ---
> > >  hw/block/virtio-blk.c |  2 +-
> > >  hw/char/virtio-serial-bus.c   |  3 +-
> > >  hw/scsi/virtio-scsi.c |  4 ++-
> > >  hw/virtio/virtio-pci.c| 14 +
> > >  hw/virtio/virtio.c| 62 
> > > ---
> > >  include/hw/virtio/virtio-access.h | 43 ---
> > >  include/hw/virtio/virtio-bus.h|  1 +
> > >  include/hw/virtio/virtio.h|  8 +++--
> > >  8 files changed, 98 insertions(+), 39 deletions(-)
> > > 
> > 
> > > diff --git a/include/hw/virtio/virtio-access.h 
> > > b/include/hw/virtio/virtio-access.h
> > > index 440b455..4071dad 100644
> > > --- a/include/hw/virtio/virtio-access.h
> > > +++ b/include/hw/virtio/virtio-access.h
> > > @@ -17,12 +17,25 @@
> > >  #define QEMU_VIRTIO_ACCESS_H
> > > 
> > >  #include "hw/virtio/virtio.h"
> > > +#include "hw/virtio/virtio-bus.h"
> > >  #include "exec/address-spaces.h"
> > > 
> > >  #if defined(TARGET_PPC64) || defined(TARGET_ARM)
> > >  #define LEGACY_VIRTIO_IS_BIENDIAN 1
> > >  #endif
> > > 
> > > +static inline AddressSpace *virtio_get_dma_as(VirtIODevice *vdev)
> > > +{
> > > +BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
> > > +VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> > > +
> > > +if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM) &&
> > > +k->get_dma_as) {
> > > +return k->get_dma_as(qbus->parent);
> > > +}
> > > +return _space_memory;
> > > +}
> > 
> > One thing I'm a bit worried about is that we're introducing a check
> > even if we know that the device will never support
> > VIRTIO_F_IOMMU_PLATFORM (i.e. virtio-ccw). The qom incantations will
> > add cycles to any invocation of this.
> 
> Yes - let's do container_of calls as opposed to QOM on data path.

BTW downstreams are building with --disable-qom-cast-debug which drops
all QOM casts on data path - one way is to say we just make this the
default upstream as well. Another to say that we want to distinguish
fast path calls from slow path, this way we will be able to bring back
some of the checks.


> > Is the address space likely to change during device lifetime? Can we
> > cache it in some way?

Re: [Qemu-block] [PATCH for 2.8 02/11] virtio: convert to use DMA api

2016-08-30 Thread Michael S. Tsirkin 
On Tue, Aug 30, 2016 at 09:31:27AM +0200, Cornelia Huck wrote:
> On Tue, 30 Aug 2016 11:06:50 +0800
> Jason Wang  wrote:
> 
> > Currently, all virtio devices bypass IOMMU completely. This is because
> > address_space_memory is assumed and used during DMA emulation. This
> > patch converts the virtio core API to use DMA API. This idea is
> > 
> > - introducing a new transport specific helper to query the dma address
> >   space. (only pci version is implemented).
> > - query and use this address space during virtio device guest memory
> >   accessing when iommu platform (VIRTIO_F_IOMMU_PLATFORM) was enabled
> >   for this device.
> > 
> > Cc: Michael S. Tsirkin 
> > Cc: Stefan Hajnoczi 
> > Cc: Kevin Wolf 
> > Cc: Amit Shah 
> > Cc: Paolo Bonzini 
> > Cc: qemu-block@nongnu.org
> > Signed-off-by: Jason Wang 
> > ---
> >  hw/block/virtio-blk.c |  2 +-
> >  hw/char/virtio-serial-bus.c   |  3 +-
> >  hw/scsi/virtio-scsi.c |  4 ++-
> >  hw/virtio/virtio-pci.c| 14 +
> >  hw/virtio/virtio.c| 62 
> > ---
> >  include/hw/virtio/virtio-access.h | 43 ---
> >  include/hw/virtio/virtio-bus.h|  1 +
> >  include/hw/virtio/virtio.h|  8 +++--
> >  8 files changed, 98 insertions(+), 39 deletions(-)
> > 
> 
> > diff --git a/include/hw/virtio/virtio-access.h 
> > b/include/hw/virtio/virtio-access.h
> > index 440b455..4071dad 100644
> > --- a/include/hw/virtio/virtio-access.h
> > +++ b/include/hw/virtio/virtio-access.h
> > @@ -17,12 +17,25 @@
> >  #define QEMU_VIRTIO_ACCESS_H
> > 
> >  #include "hw/virtio/virtio.h"
> > +#include "hw/virtio/virtio-bus.h"
> >  #include "exec/address-spaces.h"
> > 
> >  #if defined(TARGET_PPC64) || defined(TARGET_ARM)
> >  #define LEGACY_VIRTIO_IS_BIENDIAN 1
> >  #endif
> > 
> > +static inline AddressSpace *virtio_get_dma_as(VirtIODevice *vdev)
> > +{
> > +BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
> > +VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> > +
> > +if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM) &&
> > +k->get_dma_as) {
> > +return k->get_dma_as(qbus->parent);
> > +}
> > +return _space_memory;
> > +}
> 
> One thing I'm a bit worried about is that we're introducing a check
> even if we know that the device will never support
> VIRTIO_F_IOMMU_PLATFORM (i.e. virtio-ccw). The qom incantations will
> add cycles to any invocation of this.

Yes - let's do container_of calls as opposed to QOM on data path.

> Is the address space likely to change during device lifetime? Can we
> cache it in some way?

Re: [Qemu-block] [PATCH for 2.8 02/11] virtio: convert to use DMA api

2016-08-30 Thread Cornelia Huck 
On Tue, 30 Aug 2016 11:06:50 +0800
Jason Wang  wrote:

> Currently, all virtio devices bypass IOMMU completely. This is because
> address_space_memory is assumed and used during DMA emulation. This
> patch converts the virtio core API to use DMA API. This idea is
> 
> - introducing a new transport specific helper to query the dma address
>   space. (only pci version is implemented).
> - query and use this address space during virtio device guest memory
>   accessing when iommu platform (VIRTIO_F_IOMMU_PLATFORM) was enabled
>   for this device.
> 
> Cc: Michael S. Tsirkin 
> Cc: Stefan Hajnoczi 
> Cc: Kevin Wolf 
> Cc: Amit Shah 
> Cc: Paolo Bonzini 
> Cc: qemu-block@nongnu.org
> Signed-off-by: Jason Wang 
> ---
>  hw/block/virtio-blk.c |  2 +-
>  hw/char/virtio-serial-bus.c   |  3 +-
>  hw/scsi/virtio-scsi.c |  4 ++-
>  hw/virtio/virtio-pci.c| 14 +
>  hw/virtio/virtio.c| 62 
> ---
>  include/hw/virtio/virtio-access.h | 43 ---
>  include/hw/virtio/virtio-bus.h|  1 +
>  include/hw/virtio/virtio.h|  8 +++--
>  8 files changed, 98 insertions(+), 39 deletions(-)
> 

> diff --git a/include/hw/virtio/virtio-access.h 
> b/include/hw/virtio/virtio-access.h
> index 440b455..4071dad 100644
> --- a/include/hw/virtio/virtio-access.h
> +++ b/include/hw/virtio/virtio-access.h
> @@ -17,12 +17,25 @@
>  #define QEMU_VIRTIO_ACCESS_H
> 
>  #include "hw/virtio/virtio.h"
> +#include "hw/virtio/virtio-bus.h"
>  #include "exec/address-spaces.h"
> 
>  #if defined(TARGET_PPC64) || defined(TARGET_ARM)
>  #define LEGACY_VIRTIO_IS_BIENDIAN 1
>  #endif
> 
> +static inline AddressSpace *virtio_get_dma_as(VirtIODevice *vdev)
> +{
> +BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
> +VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> +
> +if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM) &&
> +k->get_dma_as) {
> +return k->get_dma_as(qbus->parent);
> +}
> +return _space_memory;
> +}

One thing I'm a bit worried about is that we're introducing a check
even if we know that the device will never support
VIRTIO_F_IOMMU_PLATFORM (i.e. virtio-ccw). The qom incantations will
add cycles to any invocation of this.

Is the address space likely to change during device lifetime? Can we
cache it in some way?

[Qemu-block] [PATCH for 2.8 02/11] virtio: convert to use DMA api

2016-08-29 Thread Jason Wang 
Currently, all virtio devices bypass IOMMU completely. This is because
address_space_memory is assumed and used during DMA emulation. This
patch converts the virtio core API to use DMA API. This idea is

- introducing a new transport specific helper to query the dma address
  space. (only pci version is implemented).
- query and use this address space during virtio device guest memory
  accessing when iommu platform (VIRTIO_F_IOMMU_PLATFORM) was enabled
  for this device.

Cc: Michael S. Tsirkin 
Cc: Stefan Hajnoczi 
Cc: Kevin Wolf 
Cc: Amit Shah 
Cc: Paolo Bonzini 
Cc: qemu-block@nongnu.org
Signed-off-by: Jason Wang 
---
 hw/block/virtio-blk.c |  2 +-
 hw/char/virtio-serial-bus.c   |  3 +-
 hw/scsi/virtio-scsi.c |  4 ++-
 hw/virtio/virtio-pci.c| 14 +
 hw/virtio/virtio.c| 62 ---
 include/hw/virtio/virtio-access.h | 43 ---
 include/hw/virtio/virtio-bus.h|  1 +
 include/hw/virtio/virtio.h|  8 +++--
 8 files changed, 98 insertions(+), 39 deletions(-)

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index 331d766..8fd6df7 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -856,7 +856,7 @@ static int virtio_blk_load_device(VirtIODevice *vdev, 
QEMUFile *f,
 }
 }
 
-req = qemu_get_virtqueue_element(f, sizeof(VirtIOBlockReq));
+req = qemu_get_virtqueue_element(vdev, f, sizeof(VirtIOBlockReq));
 virtio_blk_init_request(s, virtio_get_queue(vdev, vq_idx), req);
 req->next = s->rq;
 s->rq = req;
diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
index db57a38..94f19ba 100644
--- a/hw/char/virtio-serial-bus.c
+++ b/hw/char/virtio-serial-bus.c
@@ -682,6 +682,7 @@ static void virtio_serial_post_load_timer_cb(void *opaque)
 static int fetch_active_ports_list(QEMUFile *f,
VirtIOSerial *s, uint32_t nr_active_ports)
 {
+VirtIODevice *vdev = VIRTIO_DEVICE(s);
 uint32_t i;
 
 s->post_load = g_malloc0(sizeof(*s->post_load));
@@ -715,7 +716,7 @@ static int fetch_active_ports_list(QEMUFile *f,
 qemu_get_be64s(f, >iov_offset);
 
 port->elem =
-qemu_get_virtqueue_element(f, sizeof(VirtQueueElement));
+qemu_get_virtqueue_element(vdev, f, sizeof(VirtQueueElement));
 
 /*
  *  Port was throttled on source machine.  Let's
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index ce57ef6..4cc7627 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -197,12 +197,14 @@ static void *virtio_scsi_load_request(QEMUFile *f, 
SCSIRequest *sreq)
 SCSIBus *bus = sreq->bus;
 VirtIOSCSI *s = container_of(bus, VirtIOSCSI, bus);
 VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
+VirtIODevice *vdev = VIRTIO_DEVICE(s);
 VirtIOSCSIReq *req;
 uint32_t n;
 
 qemu_get_be32s(f, );
 assert(n < vs->conf.num_queues);
-req = qemu_get_virtqueue_element(f, sizeof(VirtIOSCSIReq) + vs->cdb_size);
+req = qemu_get_virtqueue_element(vdev, f,
+ sizeof(VirtIOSCSIReq) + vs->cdb_size);
 virtio_scsi_init_req(s, vs->cmd_vqs[n], req);
 
 if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICmdReq) + vs->cdb_size,
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 755f921..c10bf55 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1162,6 +1162,14 @@ static int virtio_pci_query_nvectors(DeviceState *d)
 return proxy->nvectors;
 }
 
+static AddressSpace *virtio_pci_get_dma_as(DeviceState *d)
+{
+VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
+PCIDevice *dev = >pci_dev;
+
+return pci_get_address_space(dev);
+}
+
 static int virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy,
struct virtio_pci_cap *cap)
 {
@@ -1587,6 +1595,11 @@ static void virtio_pci_device_plugged(DeviceState *d, 
Error **errp)
 }
 
 if (legacy) {
+if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) {
+error_setg(errp, "VIRTIO_F_IOMMU_PLATFORM was supported by"
+   "neither legacy nor transitional device.");
+return ;
+}
 /* legacy and transitional */
 pci_set_word(config + PCI_SUBSYSTEM_VENDOR_ID,
  pci_get_word(config + PCI_VENDOR_ID));
@@ -2452,6 +2465,7 @@ static void virtio_pci_bus_class_init(ObjectClass *klass, 
void *data)
 k->ioeventfd_disabled = virtio_pci_ioeventfd_disabled;
 k->ioeventfd_set_disabled = virtio_pci_ioeventfd_set_disabled;
 k->ioeventfd_assign = virtio_pci_ioeventfd_assign;
+k->get_dma_as = virtio_pci_get_dma_as;
 }
 
 static const TypeInfo virtio_pci_bus_info = {
diff --git a/hw/virtio/virtio.c