Re: [PATCH v6 13/19] x86/VPMU: Handle PMU interrupts for PV guests

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 05/22/2014 11:30 AM, Jan Beulich wrote:
>
>> @@ -99,14 +120,87 @@ int vpmu_do_rdmsr(unsigned int msr, uint64_t *msr_content)
>>           return 0;
>>   
>>       if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->do_rdmsr )
>> -        return vpmu->arch_vpmu_ops->do_rdmsr(msr, msr_content);
>> +    {
>> +        int ret = vpmu->arch_vpmu_ops->do_rdmsr(msr, msr_content);
>> +
>> +        if ( !is_hvm_domain(current->domain) &&
>> +            (current->arch.vpmu.xenpmu_data->pmu_flags & PMU_CACHED) )
> Wouldn't the same comment as in WRMSR handling apply here too?
> If so, either replicate it or add a brief comment referring to the
> other one.


Yes, the comment is applicable here too and the next patch merges the 
two routines.


>> +        /* Store appropriate registers in xenpmu_data */
>> +        if ( is_pv_32bit_domain(current->domain) )
>> +        {
>> +            /*
>> +             * 32-bit dom0 cannot process Xen's addresses (which are 64 bit)
>> +             * and therefore we treat it the same way as a non-priviledged
>> +             * PV 32-bit domain.
>> +             */
>> +            struct compat_cpu_user_regs *cmp;
>> +
>> +            gregs = guest_cpu_user_regs();
>> +
>> +            cmp = (void *)&v->arch.vpmu.xenpmu_data->pmu.r.regs;
>> +            XLAT_cpu_user_regs(cmp, gregs);
>> +            memcpy(&v->arch.vpmu.xenpmu_data->pmu.r.regs,
>> +                   &cmp, sizeof(struct compat_cpu_user_regs));
> Afaict this memcpy() does nothing (src == dst).

Yes, memcpy is unnecessary here, copying is already done by the 
preceeding XLAT_cpu_user_reg().


-boris