RE: [Xen-devel] FXSAVE instruction emulation

[Abhinav Srivastava <abhinavs_iitkgp@xxxxxxxxxxx>]

Yes, I am trying to emulate instructions step by step in some scenarios and I 
am getting this instruction. I tried skipping this instruction but it did not 
work. Do you know any patch or workaround for that?

Thanks,
Abhinav


--- On Fri, 18/7/08, Su, Disheng <disheng.su@xxxxxxxxx> wrote:

> From: Su, Disheng <disheng.su@xxxxxxxxx>
> Subject: RE: [Xen-devel] FXSAVE instruction emulation
> To: abhinavs_iitkgp@xxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx
> Cc: "Su, Disheng" <disheng.su@xxxxxxxxx>
> Date: Friday, 18 July, 2008, 8:51 AM
> Abhinav Srivastava wrote:
> > Hi there,
> > 
> > I am using Xen-3.2 on Intel-VT hardware. My guest VM
> is running Linux
> > kernel 2.6.21 in HVM mode. 
> > 
> > I was trying to do some emulation from the hypervisor
> and my code was
> > failing to emulate FXSAVE instructions. I looked on
> the mailing list
> > and found the following patch that does that:  
> > 
> > "[Xen-devel] [PATCH 2/4] Enable VirtualPC 2007
> run on top of XEN:
> > fxsave" from [Su, Disheng] 
> > 
> > However, when I applied this patch it is still not
> working. I am
> > going to the default case of this patch that directly
> calls "goto
> > cannot_emulate". When I printed the instruction
> it is like this: 0f
> > ae e8. The value of modrm_reg that patch uses to check
> which case
> > statement to execute is 05. The patch only handles the
> value 0.   
> > 
> "0f ae e8" is the lfence instruction. It
> isn't handled in this patch...
> You can refer to Intel Software Developer Manual Vol.2B
> A.4.2 for detail
> information.
> > Could some explain what does this mean? And, how to
> solve this
> > problem? 
> >
> Don't why you need to emulate this instruction...
> Do you want to emulate instructions step by step?
> How about bypass this "lfence"?
> > Any help would be appreciated.
> > 
> > Thanks,
> > Abhinav
> > 
> > 
> > 
> >       Explore your hobbies and interests. Go to
> > http://in.promos.yahoo.com/groups/ 
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> 
> 
> 
> Best Regards,
> Disheng, Su
> 
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