Re: [Xen-devel] [PATCH] x86: emulate lea with two register operands correctly

[Tim Deegan <tim@xxxxxxx>]

At 15:49 +0000 on 05 Jan (1325778595), Keir Fraser wrote:
> On 05/01/2012 15:03, "David Vrabel" <david.vrabel@xxxxxxxxxx> wrote:
> 
> > An lea instruction with two register operands should raise an
> > undefined instruction exception.
> > 
> > Skype does such a instruction and will crash when starting if it does
> > not get the exception.
> 
> Thanks. I think it is a little nicer to check ea.type != OP_MEM, so I made
> that change before committing this patch. It's now in xen-unstable staging.
> 
> It's a bit concerning that we're emulating LEA at all, perhaps. I wonder if
> a pagetable page has been reused as a code page and we didn't notice yet? Or
> is there some other reason that skype is getting emulated? :-)

#UD exceptions in HVM are passed to the emulator (IIRC as part of the
cross-vendor migration patches, so SYSENTER & friends could be managed).

Tim.

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