Re: [Xen-devel] [PATCH v11 2/3] Differentiate IO/mem resources tracked by ioreq server

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

On 1/26/2016 7:24 PM, Jan Beulich wrote:
> > > > On 26.01.16 at 08:59, <yu.c.zhang@xxxxxxxxxxxxxxx> wrote:
> > On 1/22/2016 7:43 PM, Jan Beulich wrote:
> > > > > > On 22.01.16 at 04:20, <yu.c.zhang@xxxxxxxxxxxxxxx> wrote:
> > > > @@ -2601,6 +2605,16 @@ struct hvm_ioreq_server
> > *hvm_select_ioreq_server(struct domain *d,
> > > >            type = (p->type == IOREQ_TYPE_PIO) ?
> > > >                    HVMOP_IO_RANGE_PORT : HVMOP_IO_RANGE_MEMORY;
> > > >            addr = p->addr;
> > > > +        if ( type == HVMOP_IO_RANGE_MEMORY )
> > > > +        {
> > > > +             ram_page = get_page_from_gfn(d, p->addr >> PAGE_SHIFT,
> > > > +                                          &p2mt, P2M_UNSHARE);
> > > It seems to me like I had asked before: Why P2M_UNSHARE instead
> > > of just P2M_QUERY? (This could surely be fixed up while committing,
> > > the more that I've already done some cleanup here, but I'd like to
> > > understand this before it goes in.)
> > Hah, sorry for my bad memory. :)
> > I did not found P2M_QUERY; only P2M_UNSHARE and P2M_ALLOC are
> > defined. But after reading the code in ept_get_entry(), I guess the
> > P2M_UNSHARE is not accurate, maybe I should use 0 here for the
> > p2m_query_t parameter in get_page_from_gfn()?
> Ah, sorry for the misnamed suggestion. I'm not sure whether using
> zero here actually matches your needs; P2M_UNSHARE though
> seems odd in any case, so at least switching to P2M_ALLOC (to
> populate PoD pages) would seem to be necessary.
Thanks, Jan.  :)
And now I believe we should use zero here. By now XenGT does not
support PoD and here all we care about is whether the p2m type of this
gfn is p2m_mmio_write_dm.

> > > > @@ -2642,6 +2656,11 @@ struct hvm_ioreq_server *hvm_select_ioreq_server(struct 
> > > > domain *d,
> > > >                }
> > > >
> > > >                break;
> > > > +        case HVMOP_IO_RANGE_WP_MEM:
> > > > +            if ( rangeset_contains_singleton(r, PFN_DOWN(addr)) )
> > > > +                return s;
> > > Considering you've got p2m_mmio_write_dm above - can this
> > > validly return false here?
> > Well, if we have multiple ioreq servers defined, it will...
> Ah, right. That's fine then.
>
> Jan
B.R.
Yu

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