Re: [Qemu-devel] [PATCH RFC v4 10/20] memory: add section range info for IOMMU notifier

[Alex Williamson <alex.williamson@redhat.com>]

On Fri, 20 Jan 2017 21:08:46 +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 is in 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.
> 
> Suggested-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> changelog (start from vt-d vfio enablement series v3):
> v4:
> - introduce memory_region_iommu_notifier_init() [Jason]
> ---
>  hw/vfio/common.c      | 12 +++++++++---
>  hw/virtio/vhost.c     |  4 ++--
>  include/exec/memory.h | 19 ++++++++++++++++++-
>  memory.c              |  5 ++++-
>  4 files changed, 33 insertions(+), 7 deletions(-)


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


> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 4d90844..49dc035 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -471,8 +471,13 @@ 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);
> @@ -543,7 +548,8 @@ 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 9cacf55..cc99c6a 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -1242,8 +1242,8 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
>          .priority = 10
>      };
>  
> -    hdev->n.notify = vhost_iommu_unmap_notify;
> -    hdev->n.notifier_flags = IOMMU_NOTIFIER_UNMAP;
> +    iommu_notifier_init(&hdev->n, vhost_iommu_unmap_notify,
> +                        IOMMU_NOTIFIER_UNMAP, 0, ~0ULL);
>  
>      if (hdev->migration_blocker == NULL) {
>          if (!(hdev->features & (0x1ULL << VHOST_F_LOG_ALL))) {
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index bec9756..ae4c9a9 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -81,13 +81,30 @@ 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 2bfc37f..89104b1 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1610,6 +1610,7 @@ 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);
>  }
> @@ -1671,7 +1672,9 @@ void memory_region_notify_iommu(MemoryRegion *mr,
>      }
>  
>      QLIST_FOREACH(iommu_notifier, &mr->iommu_notify, node) {
> -        if (iommu_notifier->notifier_flags & request_flags) {
> +        if (iommu_notifier->notifier_flags & request_flags &&
> +            iommu_notifier->start <= entry.iova &&
> +            iommu_notifier->end >= entry.iova) {
>              iommu_notifier->notify(iommu_notifier, &entry);
>          }
>      }