[v8,1/9] memory: add section range info for IOMMU notifier

In this patch, IOMMUNotifier.{start|end} are introduced to store section
information for a specific notifier. When notification occurs, we not
only check the notification type (MAP|UNMAP), but also check whether the
notified iova range overlaps with the range of specific IOMMU notifier,
and skip those notifiers if not in the listened range.

When removing an region, we need to make sure we removed the correct
VFIOGuestIOMMU by checking the IOMMUNotifier.start address as well.

This patch is solving the problem that vfio-pci devices receive
duplicated UNMAP notification on x86 platform when vIOMMU is there. The
issue is that x86 IOMMU has a (0, 2^64-1) IOMMU region, which is
splitted by the (0xfee00000, 0xfeefffff) IRQ region. AFAIK
this (splitted IOMMU region) is only happening on x86.

This patch also helps vhost to leverage the new interface as well, so
that vhost won't get duplicated cache flushes. In that sense, it's an
slight performance improvement.

Suggested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
v7->v8:
- let vhost dmar leverage the new interface as well
- add some more comments in commit message, mentioning what issue this
  patch has solved
- since touched up, removing Alex's a-b and DavidG's r-b
---
 hw/vfio/common.c      | 12 +++++++++---
 hw/virtio/vhost.c     | 10 ++++++++--
 include/exec/memory.h | 19 ++++++++++++++++++-
 memory.c              |  9 +++++++++
 4 files changed, 44 insertions(+), 6 deletions(-)

Hi Peter,
On 06/04/2017 09:08, Peter Xu wrote:
> In this patch, IOMMUNotifier.{start|end} are introduced to store section
> information for a specific notifier. When notification occurs, we not
> only check the notification type (MAP|UNMAP), but also check whether the
> notified iova range overlaps with the range of specific IOMMU notifier,
> and skip those notifiers if not in the listened range.
> 
> When removing an region, we need to make sure we removed the correct
> VFIOGuestIOMMU by checking the IOMMUNotifier.start address as well.
> 
> This patch is solving the problem that vfio-pci devices receive
> duplicated UNMAP notification on x86 platform when vIOMMU is there. The
> issue is that x86 IOMMU has a (0, 2^64-1) IOMMU region, which is
> splitted by the (0xfee00000, 0xfeefffff) IRQ region. AFAIK
> this (splitted IOMMU region) is only happening on x86.
I think this is likely to happen on other architectures too as "reserved
regions" are now exported to the user space.
> 
> This patch also helps vhost to leverage the new interface as well, so
> that vhost won't get duplicated cache flushes. In that sense, it's an
> slight performance improvement.
> 
> Suggested-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Peter Xu <peterx@redhat.com>
Looks good to me.
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric
> ---
> v7->v8:
> - let vhost dmar leverage the new interface as well
> - add some more comments in commit message, mentioning what issue this
>   patch has solved
> - since touched up, removing Alex's a-b and DavidG's r-b
> ---
>  hw/vfio/common.c      | 12 +++++++++---
>  hw/virtio/vhost.c     | 10 ++++++++--
>  include/exec/memory.h | 19 ++++++++++++++++++-
>  memory.c              |  9 +++++++++
>  4 files changed, 44 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index f3ba9b9..6b33b9f 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -478,8 +478,13 @@ static void vfio_listener_region_add(MemoryListener *listener,
>          giommu->iommu_offset = section->offset_within_address_space -
>                                 section->offset_within_region;
>          giommu->container = container;
> -        giommu->n.notify = vfio_iommu_map_notify;
> -        giommu->n.notifier_flags = IOMMU_NOTIFIER_ALL;
> +        llend = int128_add(int128_make64(section->offset_within_region),
> +                           section->size);
> +        llend = int128_sub(llend, int128_one());
> +        iommu_notifier_init(&giommu->n, vfio_iommu_map_notify,
> +                            IOMMU_NOTIFIER_ALL,
> +                            section->offset_within_region,
> +                            int128_get64(llend));
>          QLIST_INSERT_HEAD(&container->giommu_list, giommu, giommu_next);
>  
>          memory_region_register_iommu_notifier(giommu->iommu, &giommu->n);
> @@ -550,7 +555,8 @@ static void vfio_listener_region_del(MemoryListener *listener,
>          VFIOGuestIOMMU *giommu;
>  
>          QLIST_FOREACH(giommu, &container->giommu_list, giommu_next) {
> -            if (giommu->iommu == section->mr) {
> +            if (giommu->iommu == section->mr &&
> +                giommu->n.start == section->offset_within_region) {
>                  memory_region_unregister_iommu_notifier(giommu->iommu,
>                                                          &giommu->n);
>                  QLIST_REMOVE(giommu, giommu_next);
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 613494d..185b95b 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -736,14 +736,20 @@ static void vhost_iommu_region_add(MemoryListener *listener,
>      struct vhost_dev *dev = container_of(listener, struct vhost_dev,
>                                           iommu_listener);
>      struct vhost_iommu *iommu;
> +    Int128 end;
>  
>      if (!memory_region_is_iommu(section->mr)) {
>          return;
>      }
>  
>      iommu = g_malloc0(sizeof(*iommu));
> -    iommu->n.notify = vhost_iommu_unmap_notify;
> -    iommu->n.notifier_flags = IOMMU_NOTIFIER_UNMAP;
> +    end = int128_add(int128_make64(section->offset_within_region),
> +                     section->size);
> +    end = int128_sub(end, int128_one());
> +    iommu_notifier_init(&iommu->n, vhost_iommu_unmap_notify,
> +                        IOMMU_NOTIFIER_UNMAP,
> +                        section->offset_within_region,
> +                        int128_get64(end));
>      iommu->mr = section->mr;
>      iommu->iommu_offset = section->offset_within_address_space -
>                            section->offset_within_region;
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index f20b191..0840c89 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -77,13 +77,30 @@ typedef enum {
>  
>  #define IOMMU_NOTIFIER_ALL (IOMMU_NOTIFIER_MAP | IOMMU_NOTIFIER_UNMAP)
>  
> +struct IOMMUNotifier;
> +typedef void (*IOMMUNotify)(struct IOMMUNotifier *notifier,
> +                            IOMMUTLBEntry *data);
> +
>  struct IOMMUNotifier {
> -    void (*notify)(struct IOMMUNotifier *notifier, IOMMUTLBEntry *data);
> +    IOMMUNotify notify;
>      IOMMUNotifierFlag notifier_flags;
> +    /* Notify for address space range start <= addr <= end */
> +    hwaddr start;
> +    hwaddr end;
>      QLIST_ENTRY(IOMMUNotifier) node;
>  };
>  typedef struct IOMMUNotifier IOMMUNotifier;
>  
> +static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn,
> +                                       IOMMUNotifierFlag flags,
> +                                       hwaddr start, hwaddr end)
> +{
> +    n->notify = fn;
> +    n->notifier_flags = flags;
> +    n->start = start;
> +    n->end = end;
> +}
> +
>  /* New-style MMIO accessors can indicate that the transaction failed.
>   * A zero (MEMTX_OK) response means success; anything else is a failure
>   * of some kind. The memory subsystem will bitwise-OR together results
> diff --git a/memory.c b/memory.c
> index 4c95aaf..75ac595 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1606,6 +1606,7 @@ void memory_region_register_iommu_notifier(MemoryRegion *mr,
>  
>      /* We need to register for at least one bitfield */
>      assert(n->notifier_flags != IOMMU_NOTIFIER_NONE);
> +    assert(n->start <= n->end);
>      QLIST_INSERT_HEAD(&mr->iommu_notify, n, node);
>      memory_region_update_iommu_notify_flags(mr);
>  }
> @@ -1667,6 +1668,14 @@ void memory_region_notify_iommu(MemoryRegion *mr,
>      }
>  
>      QLIST_FOREACH(iommu_notifier, &mr->iommu_notify, node) {
> +        /*
> +         * Skip the notification if the notification does not overlap
> +         * with registered range.
> +         */
> +        if (iommu_notifier->start > entry.iova + entry.addr_mask + 1 ||
> +            iommu_notifier->end < entry.iova) {
> +            continue;
> +        }
>          if (iommu_notifier->notifier_flags & request_flags) {
>              iommu_notifier->notify(iommu_notifier, &entry);
>          }
>

On Thu, Apr 06, 2017 at 12:42:54PM +0200, Auger Eric wrote:
> Hi Peter,
> On 06/04/2017 09:08, Peter Xu wrote:
> > In this patch, IOMMUNotifier.{start|end} are introduced to store section
> > information for a specific notifier. When notification occurs, we not
> > only check the notification type (MAP|UNMAP), but also check whether the
> > notified iova range overlaps with the range of specific IOMMU notifier,
> > and skip those notifiers if not in the listened range.
> > 
> > When removing an region, we need to make sure we removed the correct
> > VFIOGuestIOMMU by checking the IOMMUNotifier.start address as well.
> > 
> > This patch is solving the problem that vfio-pci devices receive
> > duplicated UNMAP notification on x86 platform when vIOMMU is there. The
> > issue is that x86 IOMMU has a (0, 2^64-1) IOMMU region, which is
> > splitted by the (0xfee00000, 0xfeefffff) IRQ region. AFAIK
> > this (splitted IOMMU region) is only happening on x86.
> I think this is likely to happen on other architectures too as "reserved
> regions" are now exported to the user space.

Good to know this.

> > 
> > This patch also helps vhost to leverage the new interface as well, so
> > that vhost won't get duplicated cache flushes. In that sense, it's an
> > slight performance improvement.
> > 
> > Suggested-by: David Gibson <david@gibson.dropbear.id.au>
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> Looks good to me.
> Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks!

-- peterx

On Thu, Apr 06, 2017 at 03:08:36PM +0800, Peter Xu wrote:
> In this patch, IOMMUNotifier.{start|end} are introduced to store section
> information for a specific notifier. When notification occurs, we not
> only check the notification type (MAP|UNMAP), but also check whether the
> notified iova range overlaps with the range of specific IOMMU notifier,
> and skip those notifiers if not in the listened range.
> 
> When removing an region, we need to make sure we removed the correct
> VFIOGuestIOMMU by checking the IOMMUNotifier.start address as well.
> 
> This patch is solving the problem that vfio-pci devices receive
> duplicated UNMAP notification on x86 platform when vIOMMU is there. The
> issue is that x86 IOMMU has a (0, 2^64-1) IOMMU region, which is
> splitted by the (0xfee00000, 0xfeefffff) IRQ region. AFAIK
> this (splitted IOMMU region) is only happening on x86.
> 
> This patch also helps vhost to leverage the new interface as well, so
> that vhost won't get duplicated cache flushes. In that sense, it's an
> slight performance improvement.
> 
> Suggested-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Peter Xu <peterx@redhat.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

> ---
> v7->v8:
> - let vhost dmar leverage the new interface as well
> - add some more comments in commit message, mentioning what issue this
>   patch has solved
> - since touched up, removing Alex's a-b and DavidG's r-b
> ---
>  hw/vfio/common.c      | 12 +++++++++---
>  hw/virtio/vhost.c     | 10 ++++++++--
>  include/exec/memory.h | 19 ++++++++++++++++++-
>  memory.c              |  9 +++++++++
>  4 files changed, 44 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index f3ba9b9..6b33b9f 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -478,8 +478,13 @@ static void vfio_listener_region_add(MemoryListener *listener,
>          giommu->iommu_offset = section->offset_within_address_space -
>                                 section->offset_within_region;
>          giommu->container = container;
> -        giommu->n.notify = vfio_iommu_map_notify;
> -        giommu->n.notifier_flags = IOMMU_NOTIFIER_ALL;
> +        llend = int128_add(int128_make64(section->offset_within_region),
> +                           section->size);
> +        llend = int128_sub(llend, int128_one());
> +        iommu_notifier_init(&giommu->n, vfio_iommu_map_notify,
> +                            IOMMU_NOTIFIER_ALL,
> +                            section->offset_within_region,
> +                            int128_get64(llend));
>          QLIST_INSERT_HEAD(&container->giommu_list, giommu, giommu_next);
>  
>          memory_region_register_iommu_notifier(giommu->iommu, &giommu->n);
> @@ -550,7 +555,8 @@ static void vfio_listener_region_del(MemoryListener *listener,
>          VFIOGuestIOMMU *giommu;
>  
>          QLIST_FOREACH(giommu, &container->giommu_list, giommu_next) {
> -            if (giommu->iommu == section->mr) {
> +            if (giommu->iommu == section->mr &&
> +                giommu->n.start == section->offset_within_region) {
>                  memory_region_unregister_iommu_notifier(giommu->iommu,
>                                                          &giommu->n);
>                  QLIST_REMOVE(giommu, giommu_next);
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 613494d..185b95b 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -736,14 +736,20 @@ static void vhost_iommu_region_add(MemoryListener *listener,
>      struct vhost_dev *dev = container_of(listener, struct vhost_dev,
>                                           iommu_listener);
>      struct vhost_iommu *iommu;
> +    Int128 end;
>  
>      if (!memory_region_is_iommu(section->mr)) {
>          return;
>      }
>  
>      iommu = g_malloc0(sizeof(*iommu));
> -    iommu->n.notify = vhost_iommu_unmap_notify;
> -    iommu->n.notifier_flags = IOMMU_NOTIFIER_UNMAP;
> +    end = int128_add(int128_make64(section->offset_within_region),
> +                     section->size);
> +    end = int128_sub(end, int128_one());
> +    iommu_notifier_init(&iommu->n, vhost_iommu_unmap_notify,
> +                        IOMMU_NOTIFIER_UNMAP,
> +                        section->offset_within_region,
> +                        int128_get64(end));
>      iommu->mr = section->mr;
>      iommu->iommu_offset = section->offset_within_address_space -
>                            section->offset_within_region;
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index f20b191..0840c89 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -77,13 +77,30 @@ typedef enum {
>  
>  #define IOMMU_NOTIFIER_ALL (IOMMU_NOTIFIER_MAP | IOMMU_NOTIFIER_UNMAP)
>  
> +struct IOMMUNotifier;
> +typedef void (*IOMMUNotify)(struct IOMMUNotifier *notifier,
> +                            IOMMUTLBEntry *data);
> +
>  struct IOMMUNotifier {
> -    void (*notify)(struct IOMMUNotifier *notifier, IOMMUTLBEntry *data);
> +    IOMMUNotify notify;
>      IOMMUNotifierFlag notifier_flags;
> +    /* Notify for address space range start <= addr <= end */
> +    hwaddr start;
> +    hwaddr end;
>      QLIST_ENTRY(IOMMUNotifier) node;
>  };
>  typedef struct IOMMUNotifier IOMMUNotifier;
>  
> +static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn,
> +                                       IOMMUNotifierFlag flags,
> +                                       hwaddr start, hwaddr end)
> +{
> +    n->notify = fn;
> +    n->notifier_flags = flags;
> +    n->start = start;
> +    n->end = end;
> +}
> +
>  /* New-style MMIO accessors can indicate that the transaction failed.
>   * A zero (MEMTX_OK) response means success; anything else is a failure
>   * of some kind. The memory subsystem will bitwise-OR together results
> diff --git a/memory.c b/memory.c
> index 4c95aaf..75ac595 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1606,6 +1606,7 @@ void memory_region_register_iommu_notifier(MemoryRegion *mr,
>  
>      /* We need to register for at least one bitfield */
>      assert(n->notifier_flags != IOMMU_NOTIFIER_NONE);
> +    assert(n->start <= n->end);
>      QLIST_INSERT_HEAD(&mr->iommu_notify, n, node);
>      memory_region_update_iommu_notify_flags(mr);
>  }
> @@ -1667,6 +1668,14 @@ void memory_region_notify_iommu(MemoryRegion *mr,
>      }
>  
>      QLIST_FOREACH(iommu_notifier, &mr->iommu_notify, node) {
> +        /*
> +         * Skip the notification if the notification does not overlap
> +         * with registered range.
> +         */
> +        if (iommu_notifier->start > entry.iova + entry.addr_mask + 1 ||
> +            iommu_notifier->end < entry.iova) {
> +            continue;
> +        }
>          if (iommu_notifier->notifier_flags & request_flags) {
>              iommu_notifier->notify(iommu_notifier, &entry);
>          }
> -- 
> 2.7.4

On Thu,  6 Apr 2017 15:08:36 +0800
Peter Xu <peterx@redhat.com> wrote:

> In this patch, IOMMUNotifier.{start|end} are introduced to store section
> information for a specific notifier. When notification occurs, we not
> only check the notification type (MAP|UNMAP), but also check whether the
> notified iova range overlaps with the range of specific IOMMU notifier,
> and skip those notifiers if not in the listened range.
> 
> When removing an region, we need to make sure we removed the correct
> VFIOGuestIOMMU by checking the IOMMUNotifier.start address as well.
> 
> This patch is solving the problem that vfio-pci devices receive
> duplicated UNMAP notification on x86 platform when vIOMMU is there. The
> issue is that x86 IOMMU has a (0, 2^64-1) IOMMU region, which is
> splitted by the (0xfee00000, 0xfeefffff) IRQ region. AFAIK
> this (splitted IOMMU region) is only happening on x86.
> 
> This patch also helps vhost to leverage the new interface as well, so
> that vhost won't get duplicated cache flushes. In that sense, it's an
> slight performance improvement.
> 
> Suggested-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> v7->v8:
> - let vhost dmar leverage the new interface as well
> - add some more comments in commit message, mentioning what issue this
>   patch has solved
> - since touched up, removing Alex's a-b and DavidG's r-b
> ---
>  hw/vfio/common.c      | 12 +++++++++---
>  hw/virtio/vhost.c     | 10 ++++++++--
>  include/exec/memory.h | 19 ++++++++++++++++++-
>  memory.c              |  9 +++++++++
>  4 files changed, 44 insertions(+), 6 deletions(-)


Acked-by: Alex Williamson <alex.williamson@redhat.com>

> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index f3ba9b9..6b33b9f 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -478,8 +478,13 @@ static void vfio_listener_region_add(MemoryListener *listener,
>          giommu->iommu_offset = section->offset_within_address_space -
>                                 section->offset_within_region;
>          giommu->container = container;
> -        giommu->n.notify = vfio_iommu_map_notify;
> -        giommu->n.notifier_flags = IOMMU_NOTIFIER_ALL;
> +        llend = int128_add(int128_make64(section->offset_within_region),
> +                           section->size);
> +        llend = int128_sub(llend, int128_one());
> +        iommu_notifier_init(&giommu->n, vfio_iommu_map_notify,
> +                            IOMMU_NOTIFIER_ALL,
> +                            section->offset_within_region,
> +                            int128_get64(llend));
>          QLIST_INSERT_HEAD(&container->giommu_list, giommu, giommu_next);
>  
>          memory_region_register_iommu_notifier(giommu->iommu, &giommu->n);
> @@ -550,7 +555,8 @@ static void vfio_listener_region_del(MemoryListener *listener,
>          VFIOGuestIOMMU *giommu;
>  
>          QLIST_FOREACH(giommu, &container->giommu_list, giommu_next) {
> -            if (giommu->iommu == section->mr) {
> +            if (giommu->iommu == section->mr &&
> +                giommu->n.start == section->offset_within_region) {
>                  memory_region_unregister_iommu_notifier(giommu->iommu,
>                                                          &giommu->n);
>                  QLIST_REMOVE(giommu, giommu_next);
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 613494d..185b95b 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -736,14 +736,20 @@ static void vhost_iommu_region_add(MemoryListener *listener,
>      struct vhost_dev *dev = container_of(listener, struct vhost_dev,
>                                           iommu_listener);
>      struct vhost_iommu *iommu;
> +    Int128 end;
>  
>      if (!memory_region_is_iommu(section->mr)) {
>          return;
>      }
>  
>      iommu = g_malloc0(sizeof(*iommu));
> -    iommu->n.notify = vhost_iommu_unmap_notify;
> -    iommu->n.notifier_flags = IOMMU_NOTIFIER_UNMAP;
> +    end = int128_add(int128_make64(section->offset_within_region),
> +                     section->size);
> +    end = int128_sub(end, int128_one());
> +    iommu_notifier_init(&iommu->n, vhost_iommu_unmap_notify,
> +                        IOMMU_NOTIFIER_UNMAP,
> +                        section->offset_within_region,
> +                        int128_get64(end));
>      iommu->mr = section->mr;
>      iommu->iommu_offset = section->offset_within_address_space -
>                            section->offset_within_region;
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index f20b191..0840c89 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -77,13 +77,30 @@ typedef enum {
>  
>  #define IOMMU_NOTIFIER_ALL (IOMMU_NOTIFIER_MAP | IOMMU_NOTIFIER_UNMAP)
>  
> +struct IOMMUNotifier;
> +typedef void (*IOMMUNotify)(struct IOMMUNotifier *notifier,
> +                            IOMMUTLBEntry *data);
> +
>  struct IOMMUNotifier {
> -    void (*notify)(struct IOMMUNotifier *notifier, IOMMUTLBEntry *data);
> +    IOMMUNotify notify;
>      IOMMUNotifierFlag notifier_flags;
> +    /* Notify for address space range start <= addr <= end */
> +    hwaddr start;
> +    hwaddr end;
>      QLIST_ENTRY(IOMMUNotifier) node;
>  };
>  typedef struct IOMMUNotifier IOMMUNotifier;
>  
> +static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn,
> +                                       IOMMUNotifierFlag flags,
> +                                       hwaddr start, hwaddr end)
> +{
> +    n->notify = fn;
> +    n->notifier_flags = flags;
> +    n->start = start;
> +    n->end = end;
> +}
> +
>  /* New-style MMIO accessors can indicate that the transaction failed.
>   * A zero (MEMTX_OK) response means success; anything else is a failure
>   * of some kind. The memory subsystem will bitwise-OR together results
> diff --git a/memory.c b/memory.c
> index 4c95aaf..75ac595 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1606,6 +1606,7 @@ void memory_region_register_iommu_notifier(MemoryRegion *mr,
>  
>      /* We need to register for at least one bitfield */
>      assert(n->notifier_flags != IOMMU_NOTIFIER_NONE);
> +    assert(n->start <= n->end);
>      QLIST_INSERT_HEAD(&mr->iommu_notify, n, node);
>      memory_region_update_iommu_notify_flags(mr);
>  }
> @@ -1667,6 +1668,14 @@ void memory_region_notify_iommu(MemoryRegion *mr,
>      }
>  
>      QLIST_FOREACH(iommu_notifier, &mr->iommu_notify, node) {
> +        /*
> +         * Skip the notification if the notification does not overlap
> +         * with registered range.
> +         */
> +        if (iommu_notifier->start > entry.iova + entry.addr_mask + 1 ||
> +            iommu_notifier->end < entry.iova) {
> +            continue;
> +        }
>          if (iommu_notifier->notifier_flags & request_flags) {
>              iommu_notifier->notify(iommu_notifier, &entry);
>          }