From mboxrd@z Thu Jan  1 00:00:00 1970
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH v8 15/19] x86/VPMU: Merge vpmu_rdmsr and
	vpmu_wrmsr
Date: Tue, 29 Jul 2014 10:35:40 -0400
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To: Jan Beulich <JBeulich@suse.com>
Cc: kevin.tian@intel.com, keir@xen.org, suravee.suthikulpanit@amd.com, andrew.cooper3@citrix.com, tim@xen.org, dietmar.hahn@ts.fujitsu.com, xen-devel@lists.xen.org, jun.nakajima@intel.com
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On 07/29/2014 03:46 AM, Jan Beulich wrote:
>>>> On 01.07.14 at 16:37, <boris.ostrovsky@oracle.com> wrote:
>>>>
>> @@ -99,13 +99,21 @@ int vpmu_do_wrmsr(unsigned int msr, uint64_t msr_content)
>>       if ( !(vpmu_mode & XENPMU_MODE_ON) )
>>           return 0;
>>   
>> -    if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->do_wrmsr )
>> +    ASSERT((rw == VPMU_MSR_READ) || (rw == VPMU_MSR_WRITE));
>> +
>> +    if ( vpmu->arch_vpmu_ops )
>>       {
>> -        int ret = vpmu->arch_vpmu_ops->do_wrmsr(msr, msr_content);
>> +        int ret;
>>   
>> +        if ( (rw == VPMU_MSR_READ) && vpmu->arch_vpmu_ops->do_rdmsr )
>> +            ret = vpmu->arch_vpmu_ops->do_rdmsr(msr, msr_content);
>> +        else if ( vpmu->arch_vpmu_ops->do_wrmsr )
>> +            ret = vpmu->arch_vpmu_ops->do_wrmsr(msr, *msr_content);
> This won't do what you intend if rw == VPMU_MSR_READ but there's
> no ->do_rdmsr handler.

Right.

I was actually thinking about dropping checks for ops altogether 
(everywhere) and adding nop ops when needed (I think cpuid is the only one).

But if I do this it will be sometime later.


-boris