Re: [Xen-devel] [v6][PATCH 2/2] xen:vtd: missing RMRR mapping while share EPT

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

On 2014/7/30 18:47, Jan Beulich wrote:
> > > > On 30.07.14 at 12:40, <tiejun.chen@xxxxxxxxx> wrote:
> > On 2014/7/30 18:25, Jan Beulich wrote:
> > > > > > On 30.07.14 at 11:40, <tiejun.chen@xxxxxxxxx> wrote:
> > > >    From what those codes mean, it just return regardless whether they
> > > > really conflict. And this is just a good assumption, so if I'm
> > > > understanding this properly, actually our patches do this thing
> > > > precisely because we further check if this assumption is true, then take
> > > > necessary actions.
> > > Except that the pointed out check prevents the code you modify
> > > from being reached at all, i.e. as long as that check is there it
> > > doesn't matter (for any passed through USB device) what action
> > > rmrr_identity_mapping() takes.
> > Sorry, what do you mean?
> >
> >   From my point of view these two patches should be better than drop
> > simply RMRR for any PT USB device no matter if its really necessary.
> I mean that for USB devices your patches change nothing without
> said check also getting removed.
Jan,

For USB instance, I think currently we still keep that until we have a 
complete solution since this is always safe.
Additionally, I'm trying to figure out that solution. As I mentioned 
previously, I think we can reserve all RMRR once when a guest call 
XENMEM_machine_memory_map to create its own memory. What about this 
idea? Or other better suggestions?
Thanks
Tiejun

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