Re: [Xen-devel] xen-unstabel + linux 4.2: MMIO emulation failed: d23v0 64bit @ 0010:ffffffff814e2b1c -> 66 89 02 48 8d 55 c0 48 89 5d c0 44 89 65 c8 e8

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: linux@xxxxxxxxxxxxxx [mailto:linux@xxxxxxxxxxxxxx]
> Sent: 28 July 2015 22:16
> To: Andrew Cooper
> Cc: xen-devel@xxxxxxxxxxxxx; Paul Durrant
> Subject: Re: [Xen-devel] xen-unstabel + linux 4.2: MMIO emulation failed:
> d23v0 64bit @ 0010:ffffffff814e2b1c -> 66 89 02 48 8d 55 c0 48 89 5d c0 44 89
> 65 c8 e8
> 
> On 2015-07-27 16:07, Andrew Cooper wrote:
> > On 24/07/15 19:56, linux@xxxxxxxxxxxxxx wrote:
> >> Hi All,
> >>
> >> On my AMD system running xen-unstable (last commit: ),
> >>  after a few restarts of a HVM guest with pci-passthrough i got these
> >> on shutdown of the guest:
> >> (never seen this before, so it should be something triggered by a
> >> recent commit)
> >>
> >> --
> >> Sander
> >>
> >>
> >> .... (probably lost before but that's lost)
> >>
> >> (XEN) [2015-07-24 18:46:53.732] domain_crash called from io.c:166
> >> (XEN) [2015-07-24 18:46:53.732] io.c:165:d23v0 Weird HVM ioemulation
> >> status 1.
> >> (XEN) [2015-07-24 18:46:53.732] domain_crash called from io.c:166
> >> (XEN) [2015-07-24 18:46:53.732] io.c:165:d23v0 Weird HVM ioemulation
> >> status 1.
> >> (XEN) [2015-07-24 18:46:53.732] domain_crash called from io.c:166
> >> (XEN) [2015-07-24 18:46:53.732] io.c:165:d23v0 Weird HVM ioemulation
> >> status 1.
> >
> > Paul: this is very likely an issue your emulation series.
> >
> > 66 89 02 is mov %ax,(%rdx), but has ended up in handle_pio() which
> > seems
> > wrong.
> >
> > Sander: Please can you rerun with the following debug
> >
> > diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
> > index d3b9cae..7560d08 100644
> > --- a/xen/arch/x86/hvm/io.c
> > +++ b/xen/arch/x86/hvm/io.c
> > @@ -163,7 +163,9 @@ int handle_pio(uint16_t port, unsigned int size,
> > int
> > dir)
> >          break;
> >      default:
> >          gdprintk(XENLOG_ERR, "Weird HVM ioemulation status %d.\n",
> > rc);
> > -        domain_crash(curr->domain);
> > +        show_execution_state(curr);
> > +        dump_execution_state();
> > +        domain_crash_synchronous(curr->domain);
> >          break;
> >      }
> >
> > ~Andrew
> 
> 
> Hi Andrew,
> 
> I tried your debug patch, however that doesn't print anything new to xl
> dmesg.
> It seems to be too busy trying to crash .. (although that actually seems
> to fail)
> 
> This was testing on a tree with a619657e2d5725a61cb72f65901db42e98f2a896
> as last commit and it fails at the first shutdown of the guest.
> 
> After that i tried it with the current staging tree with
> 44313ab77f3e3c5b566ea4f23b0e32bfd5eafa29 as last commit
> and i don't to get those failures anymore .. i even done a start
> shutdown loop of 100 iterations .. everything was fine.
> 

Good. I can't see anything particularly relevant in the range between those two 
commits, but it doesn't sound like it's anything to do with my emulation series.

  Paul

> --
> Sander
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