Re: [Xen-devel] [PATCH 0/3 v2] XSAVE/XRSTOR fixes and enhancements

[Weidong Han <weidong.han@xxxxxxxxx>]

Keir Fraser wrote:
> On 01/09/2010 08:56, "Weidong Han" <weidong.han@xxxxxxxxx> wrote:
>
>   
> > > Well that's how it was explained to me at the time. Was that in fact wrong
> > > and we are already broken for save/restore for some subtle unexplained
> > > reason?
> > >   
> > >       
> > When XSAVE is enabled, it saves states to xsave_area in struct hvm_vcpu.
> > But hvm_save_cpu_ctxt and hvm_load_cpu_ctxt don't save/restore FPU/SSE
> > from xsave_area. So FPU/SSE states are incorrect after guest save/restore.
> >     
> Ignoring AVX, that needs fixing in 4.0 branch. The state needs pulling out
> of the xsave area and into the existing hvm_hw_cpu structure. Or, we disable
> xsave by default on 4.0.x branch. What do you think?
>
>   
I prefer to disable it by default on 4.0 branch now. After finish guest save/restore with XSAVE/XRSTOR in xen-unstable, we can port code to 4.0 branch and enable it again. 

Regards,
Weidong



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