Re: [PATCH v2 1/6] memory: reintroduce BQL-free fine-grained PIO/MMIO

[Peter Xu <peterx@redhat.com>]

On Fri, Aug 01, 2025 at 02:42:26PM +0200, Igor Mammedov wrote:
> On Wed, 30 Jul 2025 17:47:52 -0400
> Peter Xu <peterx@redhat.com> wrote:
> 
> > On Wed, Jul 30, 2025 at 02:39:29PM +0200, Igor Mammedov wrote:
> > > diff --git a/system/memory.c b/system/memory.c
> > > index 5646547940..9a5a262112 100644
> > > --- a/system/memory.c
> > > +++ b/system/memory.c
> > > @@ -2546,6 +2546,12 @@ void memory_region_clear_flush_coalesced(MemoryRegion *mr)
> > >      }
> > >  }
> > >  
> > > +void memory_region_enable_lockless_io(MemoryRegion *mr)
> > > +{
> > > +    mr->lockless_io = true;
> 
>     /*                                                                                                                                       
>      * reentrancy_guard has per device scope, that when enabled                                                                              
>      * will effectively prevent concurrent access to device's IO                                                                             
>      * MemoryRegion(s) by not calling accessor callback.                                                                                     
>      *                                                                                                                                       
>      * Turn it off for lock-less IO enabled devices, to allow                                                                                
>      * concurrent IO.                                                                                                                        
>      * TODO: remove this when reentrancy_guard becomes per transaction.          
>      */  
> 
> would something like this be sufficient?

Looks good to me, thanks!

-- 
Peter Xu