Re: [Xen-devel] [V8 PATCH 5/8] pvh dom0: Add and remove foreign pages

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.04.14 at 03:17, <mukesh.rathor@xxxxxxxxxx> wrote:
> On Mon, 24 Mar 2014 09:26:58 +0000
> "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> 
>> >>> On 22.03.14 at 02:39, <mukesh.rathor@xxxxxxxxxx> wrote:
>> > +static inline void atomic_write_ept_entry(ept_entry_t *entryptr,
> ......
>> > because it
>> > +     * will update the m2p table which will result in  mfn -> gpfn
>> > of dom0
>> > +     * and not fgfn of domU.
>> > +     */
>> > +    if ( set_foreign_p2m_entry(tdom, gpfn, _mfn(mfn)) == 0 )
>> > +        gdprintk(XENLOG_WARNING, "set_foreign_p2m_entry failed. "
>> > +                 "gpfn:%lx mfn:%lx fgfn:%lx td:%d fd:%d\n",
>> > +                 gpfn, mfn, fgfn, tdom->domain_id,
>> > fdom->domain_id);
>> > +    else
>> > +        rc = 0;
>> 
>> Can't you make set_foreign_p2m_entry() return a proper error code
>> (if it doesn't already) and use that here instead of the relatively
>> meaningless -EINVAL inherited from above (I suppose the function
>> could e.g. also return -ENOMEM)?
> 
> Well, I wsa trying to keep set_foreign_p2m_entry symmetrical with
> set_mmio_p2m_entry as they both call the common function 
> set_typed_p2m_entry which returns 0 for failure. But, no reason
> why I can't break the symmetry and flip that in set_foreign_p2m_entry.
> It could return -EINVAL for error, since could be any reason for 
> failure, invalid type or access being more likely. That is not propogated 
> back up from set_p2m_entry() unfortunately.

In the end I think we'll want to make them all report proper error
codes...

Jan


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