Re: [Qemu-devel] [PATCH] memory: add section range info for IOMMU notifier

[David Gibson]

On Wed, Nov 23, 2016 at 05:20:58PM +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 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 <address@hidden>
> Signed-off-by: Peter Xu <address@hidden>
> 
> ---
> This patch fixes the same issue with the following one:
> 
>   [PATCH] vfio: avoid adding same iommu mr for notify
> 
> Alex/David, would you please help provide some review comments on either
> of the two patches? When we can settle down the best way, then I'll drop
> the other one (I still prefer the other one...). Thanks,
> 
> Signed-off-by: Peter Xu <address@hidden>
> ---
>  hw/vfio/common.c      | 7 ++++++-
>  include/exec/memory.h | 3 +++
>  memory.c              | 4 +++-
>  3 files changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 801578b..c3db115 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -455,6 +455,10 @@ static void vfio_listener_region_add(MemoryListener 
> *listener,
>          giommu->container = container;
>          giommu->n.notify = vfio_iommu_map_notify;
>          giommu->n.notifier_flags = IOMMU_NOTIFIER_ALL;
> +        giommu->n.start = section->offset_within_address_space;

I think this needs to be offset_within_region rather than
offset_within_address_space.  The IOVAs used in the IOMMUTLBEntry are
relative to the MR, not the enclosing AS (in fact there could be
several enclosing ASes with the right aliasing).  See for example
put_tce_emu() - the (ioba - tcet->bus_offset) expression is
effectively converting the AS relative ioba into an MR relative
address.

> +        llend = int128_add(int128_make64(giommu->n.start), section->size);
> +        llend = int128_sub(llend, int128_one());
> +        giommu->n.end = int128_get64(llend);
>          QLIST_INSERT_HEAD(&container->giommu_list, giommu, giommu_next);
>  
>          memory_region_register_iommu_notifier(giommu->iommu, &giommu->n);
> @@ -525,7 +529,8 @@ 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_address_space) {

Same here.

>                  memory_region_unregister_iommu_notifier(giommu->iommu,
>                                                          &giommu->n);
>                  QLIST_REMOVE(giommu, giommu_next);
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 9728a2f..87357ea 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -84,6 +84,9 @@ typedef enum {
>  struct IOMMUNotifier {
>      void (*notify)(struct IOMMUNotifier *notifier, IOMMUTLBEntry *data);
>      IOMMUNotifierFlag notifier_flags;
> +    /* Notify for address space range start <= addr <= end */
> +    hwaddr start;
> +    hwaddr end;
>      QLIST_ENTRY(IOMMUNotifier) node;
>  };
>  typedef struct IOMMUNotifier IOMMUNotifier;
> diff --git a/memory.c b/memory.c
> index 33110e9..f89d047 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1662,7 +1662,9 @@ 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);
>          }
>      }


Apart from that, I think it looks correct.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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