Re: [Xen-devel] [PATCH v2 3/3] x86/ioreq server: Add HVMOP to map guest ram with p2m_ioreq_server to an ioreq server

["Yu, Zhang" <yu.c.zhang@xxxxxxxxxxxxxxx>]

Thanks, Tim.

On 4/4/2016 4:25 PM, Tim Deegan wrote:
> At 18:53 +0800 on 31 Mar (1459450418), Yu Zhang wrote:
> > A new HVMOP - HVMOP_map_mem_type_to_ioreq_server, is added to
> > let one ioreq server claim/disclaim its responsibility for the
> > handling of guest pages with p2m type p2m_ioreq_server. Users
> > of this HVMOP can specify whether the p2m_ioreq_server is supposed
> > to handle write accesses or read ones or both in a parameter named
> > flags. For now, we only support one ioreq server for this p2m type,
> > so once an ioreq server has claimed its ownership, subsequent calls
> > of the HVMOP_map_mem_type_to_ioreq_server will fail. Users can also
> > disclaim the ownership of guest ram pages with this p2m type, by
> > triggering this new HVMOP, with ioreq server id set to the current
> > owner's and flags parameter set to 0.
> >
> > For now, both HVMOP_map_mem_type_to_ioreq_server and p2m_ioreq_server
> > are only supported for HVMs with HAP enabled.
> "For now", meaning you intend to make this work on shadow pagetables? :P
> If not, please just say it's HAP-only.
Well, I have no clear plan in the near future to support this on shadow
mode, and I'll change the commit message in next version. :)

> > diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c
> > index c81302a..2e0d258 100644
> > --- a/xen/arch/x86/mm/shadow/multi.c
> > +++ b/xen/arch/x86/mm/shadow/multi.c
> > @@ -3224,8 +3224,7 @@ static int sh_page_fault(struct vcpu *v,
> >       }
> >
> >       /* Need to hand off device-model MMIO to the device model */
> > -    if ( p2mt == p2m_mmio_dm
> > -         || (p2mt == p2m_ioreq_server && ft == ft_demand_write) )
> > +    if ( p2mt == p2m_mmio_dm )
> >       {
> >           gpa = guest_walk_to_gpa(&gw);
> >           goto mmio;
> Acked-by: Tim Deegan <tim@xxxxxxx>
Regards.
Yu

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