Re: [Xen-devel] [PATCH 2/2] libxl: fix osvm cpuid flag

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Wed, Jun 28, 2017 at 11:16:33AM +0100, Andrew Cooper wrote:
> On 28/06/17 07:09, Jan Beulich wrote:
> >>>> Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx> 06/28/17 
> >>>> 3:09 AM >>>
> >> It's bit 9 not 10 (which is ibs).
> > Indeed, but shouldn't it rather be removed? We don't expose it from the
> > hypervisor at all anymore:
> >
> > XEN_CPUFEATURE(OSVW,          3*32+ 9) /*   OS Visible Workaround */
> >
> > (note the absence of any marker character immediately inside the comment).
> 
> I don't believe we have ever actually offered OSVW to guests, despite
> the pretence of being able to.  ISTR it was always clobbered before
> being given to a guest.
> 
> Having said that, we should be advertising OSVW.  It's entire purpose is
> to tell the OS that there is something it can do to manually work round
> a specific erratum.  OTOH, making this migrate safe is liable to be very
> complicated...

I don't have opinion on either approach here, but the current state is
clearly wrong. You've got two versions of the patch, choose one ;)

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

Attachment: signature.asc
Description: PGP signature

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel