Re: [Xen-devel] [RFC][PATCH 3/5] tools:libxc: remove mmio BAR out of RMRR mappings

["Chen, Tiejun" <tiejun.chen@xxxxxxxxx>]

On 2014/8/9 5:33, Tian, Kevin wrote:
> > From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> > Sent: Friday, August 08, 2014 8:49 AM
> >
> > > > > On 07.08.14 at 13:02, <tiejun.chen@xxxxxxxxx> wrote:
> > > @@ -300,6 +302,30 @@ static int setup_guest(xc_interface *xch,
> > >           goto error_out;
> > >       }
> > >
> > > +    /* We need to move mmio range out of RMRR mapping. */
> > > +    rc = xc_get_rmrr_map(xch, map, E820MAX);
> > > +    if (rc < 0)
> > > +    {
> > > +        PERROR("Could not get RMRR info on domain");
> > > +    }
> > > +    else if ( rc )
> > > +    {
> > > +        for ( i = 0; i < rc; i++ )
> > > +        {
> > > +            rmrr_end = map[i].addr + map[i].size + 1;
> > > +            if ( rmrr_end > mmio_start )
> > > +            {
> > > +                mmio_start = rmrr_end;
> > > +            }
> > > +        }
> > This seems way too simplistic - what if the RMRRs are referring to
> > memory regions extremely far apart?
> >
> > > +        mmio_size = (1ull << 32) - mmio_start;
> > Limiting things to 4Gb?
> >
> > > +        if ( mmio_size <= 0 )
> > mmio_size is an unsigned quantity, so this won't do what you intend.
> and it's not only about the start of mmio, but also the confliction with normal
> guest memory pages, i.e. all the populate_physmap calls should check with
RMRR maps should be as reserved by Xen, right? So why will we still 
check this? I mean Xen should guarantee we don't allocate those reserved 
pages to guest.
Thanks
Tiejun

> RMRR ranges.
>
> Thanks
> Kevin
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel