Re: [Xen-devel] [PATCH v4 02/15] x86/cpu: Fix common cpuid faulting probing for AMD and Hygon

[Pu Wen <puwen@xxxxxxxx>]

On 2019/4/2 23:46, Jan Beulich wrote:
> On 02.04.19 at 13:58, <puwen@xxxxxxxx> wrote:
> > On 2019/4/2 18:20, Jan Beulich wrote:
> > > On 02.04.19 at 08:46, <puwen@xxxxxxxx> wrote:
> > > > On 2019/4/1 16:41, Jan Beulich wrote:
> > > > > On 30.03.19 at 11:42, <puwen@xxxxxxxx> wrote:
> > > > > > There is no MSR_INTEL_PLATFORM_INFO for AMD and Hygon families. So directly
> > > > > > return false in the function probe_cpuid_faulting() if !cpu_has_hypervisor.
> > > > > I think it would have been nice if you had mentioned the real
> > > > > reason why you want to bypass the MSR accesses. This way it
> > > > > sounds as if the change was only cosmetic, and hence could be
> > > > > left out.
> > > > Okay, how about the new description:
> > > > There is no MSR_INTEL_PLATFORM_INFO for AMD and Hygon families. Read
> > > > this MSR will stop the Xen initialization process
> > > "... for some early Hygon steppings"(?). I'm unaware of AMD CPUs
> > Yes,for some early Hygon steppings.
> >
> > > having this issue - are you telling us otherwise?
> > I tested with an AMD CPU(Family 17h, Model 1, Stepping 1) today, and
> > it also stopped when reading the MSR_INTEL_PLATFORM_INFO instead of
> > producing #GP(0).
> I've yet to try it out on my Rome system, but I have to admit I
We have Rome system too, I'll have a try on it as well.

> find this hard to believe. Andrew - you've tried to boot Xen on a
> Rome already. Iirc you said it crashed, but did it perhaps get to
> (and past) this point?
--
Regards,
Pu Wen

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