Re: [Qemu-devel] [PATCH v3 1/8] memory: address_space_iterate

[Paolo Bonzini <pbonzini@redhat.com>]

On 12/12/2017 11:31, Dr. David Alan Gilbert wrote:
> * Paolo Bonzini (pbonzini@redhat.com) wrote:
>> On 11/12/2017 20:46, Dr. David Alan Gilbert (git) wrote:
>>> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>>>
>>> Iterate through an address space calling a function for each
>>> section.  The iteration is done in order.
>>>
>>> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>>
>> It seems to me that you can achieve the same effect by implementing the
>> region_add and region_nop callbacks, and leaving out region_del.  Am I
>> missing something?
> 
> What's the semantics of region_nop (and for that matter region_add/del)?

nop means that attributes (readonly, romd_mode, mr+offset_in_region)
haven't changed; nop is optionally followed by log_start or log_stop.
If any of them changes, you get del+add (del is always before add).

> Th nice thing we have here is we get a full walk of the physical memory
> in order; keeping it in order makes our data structure easy for merging.

That's the same that you get with region_del/add.

Thanks,

Paolo

> Dave
> 
> 
>> Thanks,
>>
>> Paolo
>>
>>> ---
>>>  include/exec/memory.h | 23 +++++++++++++++++++++++
>>>  memory.c              | 22 ++++++++++++++++++++++
>>>  2 files changed, 45 insertions(+)
>>>
>>> diff --git a/include/exec/memory.h b/include/exec/memory.h
>>> index 5ed4042f87..f5a9df642e 100644
>>> --- a/include/exec/memory.h
>>> +++ b/include/exec/memory.h
>>> @@ -1987,6 +1987,29 @@ address_space_write_cached(MemoryRegionCache *cache, hwaddr addr,
>>>      address_space_write(cache->as, cache->xlat + addr, MEMTXATTRS_UNSPECIFIED, buf, len);
>>>  }
>>>  
>>> +/**
>>> + * ASIterateCallback: Function type called by address_space_iterate
>>> + *
>>> + * Return 0 on success or a negative error code.
>>> + *
>>> + * @mrs: Memory region section for this range
>>> + * @opaque: The opaque value passed in to the iterator.
>>> + */
>>> +typedef int (*ASIterateCallback)(MemoryRegionSection *mrs, void *opaque);
>>> +
>>> +/**
>>> + * address_space_iterate: Call the function for each address range in the
>>> + *                        AddressSpace, in sorted order.
>>> + *
>>> + * Return 0 on success or a negative error code.
>>> + *
>>> + * @as: Address space to iterate over
>>> + * @cb: Function to call.  If the function returns none-0 the iteration will
>>> + *     stop.
>>> + * @opaque: Value to pass to the function
>>> + */
>>> +int
>>> +address_space_iterate(AddressSpace *as, ASIterateCallback cb, void *opaque);
>>>  #endif
>>>  
>>>  #endif
>>> diff --git a/memory.c b/memory.c
>>> index e26e5a3b1d..f45137f25e 100644
>>> --- a/memory.c
>>> +++ b/memory.c
>>> @@ -2810,6 +2810,28 @@ void address_space_destroy(AddressSpace *as)
>>>      call_rcu(as, do_address_space_destroy, rcu);
>>>  }
>>>  
>>> +int address_space_iterate(AddressSpace *as, ASIterateCallback cb,
>>> +                          void *opaque)
>>> +{
>>> +    int res = 0;
>>> +    FlatView *fv = address_space_to_flatview(as);
>>> +    FlatRange *range;
>>> +
>>> +    flatview_ref(fv);
>>> +
>>> +    FOR_EACH_FLAT_RANGE(range, fv) {
>>> +        MemoryRegionSection mrs = section_from_flat_range(range, fv);
>>> +        res = cb(&mrs, opaque);
>>> +        if (res) {
>>> +            break;
>>> +        }
>>> +    }
>>> +
>>> +    flatview_unref(fv);
>>> +
>>> +    return res;
>>> +}
>>> +
>>>  static const char *memory_region_type(MemoryRegion *mr)
>>>  {
>>>      if (memory_region_is_ram_device(mr)) {
>>>
>>
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
>