Re: [Qemu-devel] [PATCH RFC v3 07/14] memory: add section range info for IOMMU notifier

[Jason Wang <jasowang@redhat.com>]

On 2017年01月13日 17:23, Peter Xu wrote:
> On Fri, Jan 13, 2017 at 03:55:22PM +0800, Jason Wang wrote:
>>
>> On 2017年01月13日 11:06, 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 <david@gibson.dropbear.id.au>
>>> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
>>> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
>>> Signed-off-by: Peter Xu <peterx@redhat.com>
>>> ---
>>>   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..6f648da 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_region;
>>> +        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_region) {
>>>                   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 bec9756..7649e74 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 2bfc37f..e88bb54 100644
>>> --- a/memory.c
>>> +++ b/memory.c
>>> @@ -1671,7 +1671,9 @@ 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);
>>>           }
>>>       }
>> This seems breaks vhost device IOTLB. How about keep the the behavior
>> somehow?
> Thanks to point out. How about I squash this into this patch?
>
> --------8<--------
> diff --git a/memory.c b/memory.c
> index e88bb54..6de02dd 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1608,8 +1608,14 @@ void memory_region_register_iommu_notifier(MemoryRegion *mr,
>           return;
>       }
>   
> +    if (n->start == 0 && n->end == 0) {
> +        /* If these are not specified, we listen to the whole range */
> +        n->end = (hwaddr)(-1);
> +    }
> +
>       /* 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);
>   }
> -------->8--------
>
> -- peterx

This should work, or you can introduce a 
memory_region_iommu_notifier_init() to force user to explicitly 
initialize start and end.

Thanks