Re: [Xen-ia64-devel] VT-i: general exception

[Tristan Gingold <Tristan.Gingold@xxxxxxxx>]

Le Mardi 11 Avril 2006 10:49, Xu, Anthony a écrit :
> From: Tristan Gingold
>
> >Sent: 2006?4?11? 16:47
> >
> >Le Mardi 11 Avril 2006 03:17, Xu, Anthony a écrit :
> >> From: Tristan Gingold
> >>
> >> >Sent: 2006?4?11? 0:03
> >> >To: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> >> >Subject: [Xen-ia64-devel] VT-i: general exception
> >> >
> >> >Hi,
> >> >
> >> >inside vmx_ivt.S:
> >> >
> >> >// 0x5400 Entry 24 (size 16 bundles) General Exception
> >> > (5,32,34,36,38,39) ENTRY(vmx_general_exception)
> >> >    VMX_DBG_FAULT(24)
> >> >    VMX_FAULT(24)
> >> >//    VMX_REFLECT(24)
> >> >END(vmx_general_exception)
> >> >
> >> >IIRC, VMX_FAULT is an infinite loop.  Therefore, in case of general
> >> > exception raised at the hots IVT, xen locks.
> >> >
> >> >Is it a bug or something not finished ?
> >>
> >> It's not a bug, normally general exception will not happen in guest,
> >> If it does happen, that means something wrong, it was used for
> >> debugging.
> >
> >???
> >
> >Try this program:
> >
> >int main(void)
> >{
> >  int a = *(volatile int *)0xf000000000000000;
> >}
> >
> >This locks up Xen!
>
> Ideally gp fault should be injected into guest.
No.  Xen-Vti set 'opcode' virtual env parameter to 1.
Therefore according to 5.2.2, some GF are raised at the *host* IVT.

> Again, this was only used for debugging tricky issue
> happening inside VMM.
This is wrong.  This simple program locks Xen-Vti, but it shouldn't.

Tristan.



_______________________________________________
Xen-ia64-devel mailing list
Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-ia64-devel