Re: [Xen-devel] [PATCH] use compat_*() for all 32-bit hypercalls.

[Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>]

At 16:25 +0100 on 10 May (1305044704), George Dunlap wrote:
> Is this a problem for 4.1 as well, or are the lockups in HVMloader
> xenbus in code that's been introduced since then?

This affects all hvmloaders that use xenbus, which I think includes 4.1

Tim.

> On Tue, May 10, 2011 at 1:55 PM, Tim Deegan <Tim.Deegan@xxxxxxxxxx> wrote:
> > The attached patch switches the handling of sched_op, get_xen_version
> > and set_timer_op hypercalls from 32-bit HVM guests to use the compat
> > versions of the handlers.  As far as I can see this is correcting an
> > oversight: other hypercalls are already redirected to the compat
> > versions and having a mix of translated and untranslated seems like the
> > worst option.
> >
> > The only one of these three that's likely to cause trouble is schedop
> > (poll) which almost always happens to work if you call the wrong
> > version.  However the interlock against concurrent event arrival
> > doesn't work, which was leading to lockups in the HVMloader xenbus code.
> >
> > Cc'ing various people who I know are responsible for HVM PV drivers just
> > in case any ofthem have hardcoded this broken interface into client
> > code.
> >
> > Cheers,
> >
> > Tim.
> >
> > --
> > Tim Deegan <Tim.Deegan@xxxxxxxxxx>
> > Principal Software Engineer, Xen Platform Team
> > Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> >
> >

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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