Re: [Xen-devel] [V10 PATCH 10/23] PVH xen: domain create, context switch related code changes

[Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>]

On Tue, 20 Aug 2013 10:29:24 +0100
George Dunlap <George.Dunlap@xxxxxxxxxxxxx> wrote:

> On Tue, Aug 20, 2013 at 1:52 AM, Mukesh Rathor
> <mukesh.rathor@xxxxxxxxxx> wrote:
> > On Fri, 16 Aug 2013 17:11:21 +0100
> > "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> >
> >> >>> On 16.08.13 at 17:32, George Dunlap
> >> >>> <George.Dunlap@xxxxxxxxxxxxx> wrote:
> >> > On Wed, Jul 24, 2013 at 2:59 AM, Mukesh Rathor
> > ......
> >> >>
> >> >>      set_bit(_VPF_in_reset, &v->pause_flags);
> >> >>
> >> >> + pvh_skip_pv_stuff:
> >> >
> >> > Any idea what this set_bit(_VPF_in_reset) stuff is?  It looks
> >> > like it's set above, and cleared down near the bottom of the
> >> > function if nothing gets screwed up.
> >>
> >> This is related to the preemptible vCPU reset (which
> >> arch_set_info_guest() just re-uses), making sure that while there
> >> is an incomplete state update for a vCPU 8because it may have got
> >> preempted) the vCPU can't be unpaused.
> >>
> >> > It seems like if that set/clear pair is important, then PVH
> >> > should do them both as well, shouldn't it?
> >>
> >> I thought I had checked this once - does it now bypass one of the
> >> two?
> >>
> >> But then again, this is all about PV memory management, so perhaps
> >> it was that way when I checked, and I decided it was fine.
> >
> > Ok, I'll just leave it as it is then. Setting it might confuse
> > someone why it's being set for PVH. Clearing is harmless anyways :).
> 
> I think much more confusing is skipping the set.  Part of the reason I
> was asking is that I was looking at re-organizing the function so that
> all the stuff common to PVH and PV were at the top; Then instead of
> the goto, you would just have two return's, one for HVM, one for PVH,
> at the appropriate place; I backed off and asked when I saw this.

Ok, i moved the goto target above the set. So it gets set for PVH also.

thanks,
mukesh


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel