Re: [Qemu-devel] [PATCH] memory.h: Improve IOMMU related documentation

[Peter Maydell]

On 30 April 2018 at 14:08, Paolo Bonzini <address@hidden> wrote:
> On 30/04/2018 14:57, Peter Maydell wrote:
>> On 30 April 2018 at 13:54, Paolo Bonzini <address@hidden> wrote:
>>> On 30/04/2018 14:24, Peter Maydell wrote:
>>>> -    /* Set this up to provide customized IOMMU replay function */
>>>> +    /* Set this up to provide customized IOMMU replay function.
>>>> +     * Optional method.
>>>> +     */
>>>>      void (*replay)(IOMMUMemoryRegion *iommu, IOMMUNotifier *notifier);
>>>
>>> replay is needed if you want to support IOMMU notifiers.  After
>>> memory_region_register_iommu_notifier you're only notified about future
>>> changes to the mappings; memory_region_iommu_replay calls the replay
>>> method so that the IOMMUNotifier is called for each existing mapping.
>>
>> Is it then unrelated to record-and-replay ? That's what I guessed
>> it was for... Also, some IOMMUs (eg spapr_iommu.c) seem to support
>> notifiers but don't implement it.
>
> Yes, it's completely unrelated.  I have no idea why spapr_iommu.c
> doesn't need it, so I am CCing the sPAPR and VFIO experts...

There does seem to be a default implementation in
memory_region_iommu_replay(), maybe that is sufficient for spapr?

thanks
-- PMM