From mboxrd@z Thu Jan  1 00:00:00 1970
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH v3 05/16] x86/VPMU: Handle APIC_LVTPC
	accesses
Date: Mon, 13 Jan 2014 10:04:40 -0500
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To: Jan Beulich <JBeulich@suse.com>
Cc: keir@xen.org, suravee.suthikulpanit@amd.com, andrew.cooper3@citrix.com, eddie.dong@intel.com, dietmar.hahn@ts.fujitsu.com, jun.nakajima@intel.com, xen-devel <xen-devel@lists.xenproject.org>
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On 01/13/2014 08:28 AM, Jan Beulich wrote:
>>>> On 06.01.14 at 20:24, Boris Ostrovsky <boris.ostrovsky@oracle.com> wrote:
>> Update APIC_LVTPC vector when HVM guest writes to it.
>>
>> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

...

>> +void vpmu_lvtpc_update(uint32_t val)
>> +{
>> +    struct vpmu_struct *vpmu = vcpu_vpmu(current);
>> +
>> +    vpmu->hw_lapic_lvtpc = PMU_APIC_VECTOR | (val & APIC_LVT_MASKED);
>> +    apic_write(APIC_LVTPC, vpmu->hw_lapic_lvtpc);
>> +}
>> +
>>   int vpmu_do_wrmsr(unsigned int msr, uint64_t msr_content)
>>   {
>>       struct vpmu_struct *vpmu = vcpu_vpmu(current);
>> @@ -227,19 +235,21 @@ void vpmu_initialise(struct vcpu *v)
>>       case X86_VENDOR_AMD:
>>           if ( svm_vpmu_initialise(v, opt_vpmu_enabled) != 0 )
>>               opt_vpmu_enabled = 0;
>> -        break;
>> +        return;
>>   
>>       case X86_VENDOR_INTEL:
>>           if ( vmx_vpmu_initialise(v, opt_vpmu_enabled) != 0 )
>>               opt_vpmu_enabled = 0;
>> -        break;
>> +        return;
>>   
>>       default:
>>           printk("VPMU: Initialization failed. "
>>                  "Unknown CPU vendor %d\n", vendor);
>>           opt_vpmu_enabled = 0;
>> -        break;
>> +        return;
>>       }
>> +
>> +    vpmu->hw_lapic_lvtpc = PMU_APIC_VECTOR | APIC_LVT_MASKED;
>>   }
> So what is this good for? All code paths above use "return" now,
> hence how would execution get here?

Yes, it shouldn't be here. I could move it up but since we are now 
updating LVTPC explicitly when a guest is writing APIC I think I can 
just drop it altogether.

-boris