Re: Bug: cpu0 unhandled rdmsr: 0x1900 and inject_general_protection

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

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TJ wrote:
> Trying to run the latest OLPC XO guest image with kvm-intel on 2.6.22
> x86_64 (Ubuntu Gutsy) on a T7200 there are critical problems which don't
> occur if kvm-intel is not loaded/used.
>
> The same issue affects kvm-48, kvm-50 and kvm-51.
>
> I don't see these problems with Gutsy or Windows guests. The issues are:
>
> 1. Start-up of the image into GRUB is _slow_. The cursor can be seen
> scanning as the GRUB menu is drawn. It is *much* faster when kvm-intel
> isn't loaded/used.
>
> 2. After choosing a boot option the guest freezes and the host kern.log
> reports:
>
> kernel: [88380.014893] kvm: 12666: cpu0 unhandled rdmsr: 0x1900
> kernel: [88380.014900] inject_general_protection: rip 0xc07211ab
>
> 3. Guest locks up at this point with host CPU being driven 100% and requires killing.
>
>
> I'm guessing they may be related to the OLPC kernel expecting an AMD Geode CPU?
>
> ./include/asm-i386/msr.h
> #define MSR_GEODE_BUSCONT_CONF0 0x1900
>
>   

Very likely.  Try the attached patch.  The guest may hang later with 
another bad msr; you can simply add more registers as necessary.

I think we can add an API to do this from userspace, to avoid the need 
to patch the kernel for hundreds of no-op msrs.


-- 
error compiling committee.c: too many arguments to function


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diff --git a/kernel/x86.c b/kernel/x86.c
index e905d46..71307cb 100644
--- a/kernel/x86.c
+++ b/kernel/x86.c
@@ -460,6 +460,7 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
 	case MSR_IA32_UCODE_REV:
 	case MSR_IA32_PERF_STATUS:
 	case MSR_IA32_EBL_CR_POWERON:
+	case MSR_GEODE_BUSCONT_CONF0:
 		/* MTRR registers */
 	case 0xfe:
 	case 0x200 ... 0x2ff:

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