Re: [Xen-devel] [PATCH v2 3/3] paravirt: rename paravirt_enabled to paravirt_legacy

[Boris Ostrovsky]

On 02/08/2016 11:45 AM, Borislav Petkov wrote:
> On Mon, Feb 08, 2016 at 04:38:40PM +0000, Andrew Cooper wrote:
> > Does the early loader have extable support?  If so, this is fairly easy
> > to fix.  If not, we have a problem.
> It doesn't and regardless, you want to have this CPUID querying as
> simple as possible. No special handling, no special prefixes as it
> should be able to run on other hypervisors too.
>
> If one can't execute a simple CPUID(0x4...) on a xen guest and get the
> results back, then for early, we will have to do what we've done until
> now and simply emulate the MSR accesses.

I think xen_hypervisor check can be done in microcode_init() as this is 
first time PV kernel deals with microcode.

Let me try it --- I want to see what happens on hotplug and resume but I 
am reasonably certain this should work during boot.

-boris

> Later code can use then xen_cpuid() and all is fine. We should still get
> rid of paravirt_enabled() though.