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

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Paolo Bonzini (pbonzini@redhat.com) wrote:
> 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.

Hmm it would be good if that was documented somewhere.
I thought you'd only get an _add/_del and then a commit.

However, what do I do in vhost_dev_start?  At the moment I'm forcfully
regenerating it using the same code.

Dave

> 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
> > 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK