Re: [Qemu-devel] [PATCH 0/2] VFIO: Make 8-byte accesses atomic

[Alex Williamson <alex.williamson@redhat.com>]

On Tue, 2 May 2017 23:41:01 -0300
joserz@linux.vnet.ibm.com wrote:

> On Fri, Apr 21, 2017 at 12:06:15PM +0200, Paolo Bonzini wrote:
> > 
> > 
> > On 20/04/2017 18:03, Alex Williamson wrote:  
> > > On Thu, 20 Apr 2017 00:19:23 -0700
> > > Richard Henderson <rth@twiddle.net> wrote:
> > >   
> > >> On 04/19/2017 12:44 PM, Jose Ricardo Ziviani wrote:  
> > >>> This patchset has two patches:
> > >>> [1] 8-byte writes to non-mapped MMIO are broken into pairs of 4-byte writes, this patch makes such pairs atomic.
> > >>>
> > >>> [2] Enable 8-byte accesses in vfio_region_write and vfio_region_read.
> > >>>
> > >>> Patches based on master.
> > >>>
> > >>> Jose Ricardo Ziviani (2):
> > >>>   vfio: Set MemoryRegionOps:max_access_size and min_access_size
> > >>>   vfio: enable 8-byte reads/writes to vfio
> > >>>
> > >>>  hw/vfio/common.c | 14 ++++++++++++++
> > >>>  1 file changed, 14 insertions(+)
> > >>>    
> > >>
> > >> I think these patches need to be squashed to be bisectable.  
> > > 
> > > No, I think it's fine.  The point of patch 1/2 is to indicate that the
> > > hardware supports 8-byte accesses, which will still be broken into 2
> > > 4-byte accesses because we don't yet set the implemented width beyond
> > > the default.  The important part is that the mutex will now group the 4
> > > byte access pair together rather than letting them get re-ordered.
> > > Patch 2/2 then implements native 8-byte access.  I appreciate them
> > > being separate for this subtle nuance, but maybe I'm not seeing the
> > > same issue as you.  Thanks,  
> > '
> > I agree, the patches looks fine as is.
> > 
> > Paolo
> >   
> 
> Hello!
> 
> Thank you all for your review but I have a quick question: is it ok for
> merge? :)

Yes, I've got it in a local branch, I'll send a pull request this
week.  Thanks,

Alex