Re: [Xen-devel] Restoring FPU exception state

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: 18 February 2016 08:16
> To: Kevin Tian
> Cc: Andrew Cooper; David Vrabel; Paul Durrant; Feng Wu; xen-devel
> Subject: RE: Restoring FPU exception state
> 
> >>> On 18.02.16 at 07:30, <kevin.tian@xxxxxxxxx> wrote:
> > Interesting. Let me also have a check internally whether there is other
> > architectural alternative. BTW, not quite related. Could I think finally
> > Xen may allow user to specify OS type as a general per-domain control,
> > and then Xen can do free optimizations underlying based on that type?
> > I don't expect we want to expose raw FPU related per-domain control
> > since it's difficult for users to correctly set it up...
> 
> So what if then, with us implying some kind of workaround here
> from the OS type, someone set the OS type to Windows, and
> subsequently MS decided to fix their issue?

We already get full OS version information from Windows via the 
VIRIDIAN_MSR_GUEST_OS_ID MSR so it would be quite straightforward to work 
around the issue for all Windows at the moment and then make the check more 
specific if Microsoft choose to avoid the problem by some other means.

  Paul

> 
> Jan


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