Re: [RFT] Fix for unhandled msr c0000081 problems under Intel cpus

* Avi Kivity <avi@xxxxxxxxxxxx> wrote:

> Ingo Molnar wrote:
> >* Avi Kivity <avi@xxxxxxxxxxxx> wrote:
> >
> >  
> >>>that did the trick. The only messages remaining are:
> >>>
> >>>kvm: unhandled wrmsr: 0xc1
> >>>inject_general_protection: rip 0xc011b8ae
> >>>
> >>> 
> >>>      
> >>That's a performance counter.  What guest triggers it?
> >>    
> >
> >a 32-bit Linux bzImage:
> >
> >  c011b8ae:       0f 30                   wrmsr
> >
> > (gdb) list *0xc011b8ae
> > 0xc011b8ae is in setup_apic_nmi_watchdog (include/asm/msr.h:36).
> > 31      static inline void wrmsrl (unsigned long msr, unsigned long long 
> > val)
> > 32      {
> > 33              unsigned long lo, hi;
> > 34              lo = (unsigned long) val;
> > 35              hi = val >> 32;
> > 36              wrmsr (msr, lo, hi);
> > 37      }
> > 38
> > 39      /* wrmsr with exception handling */
> > 40      #define wrmsr_safe(msr,a,b) ({ int ret__;                         
> >
> >the guest also obviously crashes due to this #GPF.
> >  
> 
> The wary ones use wrmsr_safe().
> 
> >[ 2.6.20-rc2-rt2 kernel of course ;-) ]
> >
> >  
> 
> Who's the caller?  I boot 2.6.18 variants regularly and they don't touch 
> that msr.

the caller is in the gdb dump above:

> > 0xc011b8ae is in setup_apic_nmi_watchdog (include/asm/msr.h:36).

i'll change it to wrmsr_safe().

        Ingo

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