Re: [PATCH] KVM: x86: fix bogus warning about reserved bits

[Xiao Guangrong]

On 09/25/2015 03:49 PM, Paolo Bonzini wrote:
> On 24/09/2015 12:12, Borislav Petkov wrote:
> > On Thu, Sep 24, 2015 at 11:23:08AM +0800, Xiao Guangrong wrote:
> > > > +static inline bool
> > > > +boot_cpu_is_amd(void)
> > > > +{
> > > > +	WARN_ON_ONCE(!tdp_enabled);
> > > > +	return shadow_x_mask != 0;
> > >
> > > shadow_x_mask != 0 is Intel's CPU.
> > >
> > > Borislav, could you please check shadow_x_mask == 0 instead and test it again?
> >
> > That did the trick:
> >
> > [   62.640392] kvm: zapping shadow pages for mmio generation wraparound
> > [   63.100301] cpuid(0).ebx = 68747541
> > [   63.193426] kvm [3748]: vcpu0 unhandled rdmsr: 0xc0010112
> > [   64.538294] kvm [3748]: vcpu0 unhandled rdmsr: 0xc0011021
> > [   64.866263] kvm [3748]: vcpu1 unhandled rdmsr: 0xc0011021
> > [   64.971972] kvm [3748]: vcpu2 unhandled rdmsr: 0xc0011021
> > [   65.070376] kvm [3748]: vcpu3 unhandled rdmsr: 0xc0011021
> > [   65.170625] kvm [3748]: vcpu4 unhandled rdmsr: 0xc0011021
> > [   65.272838] kvm [3748]: vcpu5 unhandled rdmsr: 0xc0011021
> > [   65.374288] kvm [3748]: vcpu6 unhandled rdmsr: 0xc0011021
> > [   65.474825] kvm [3748]: vcpu7 unhandled rdmsr: 0xc0011021
> >
> > That's all I got in dmesg from booting the guest - no more mmio PF
> > warnings.
>
> Great, though this doesn't yet explain why guest_cpuid_is_amd failed.
> I'll look into it next week when Amazon delivers my shiny new AMD
> mini-PC :) and send the patch to Linus meanwhile.

I guess QEMU passed AMD cpu mode to KVM... but not sure. :(
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