From mboxrd@z Thu Jan  1 00:00:00 1970
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH v12 for-xen-4.5 12/20] x86/VPMU: Initialize
 PMU for PV(H) guests
Date: Mon, 29 Sep 2014 11:41:23 -0400
Message-ID: <54297DA3.30200@oracle.com>
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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, Aravind.Gopalakrishnan@amd.com, jun.nakajima@intel.com, dgdegra@tycho.nsa.gov
List-Id: xen-devel@lists.xenproject.org

On 09/29/2014 11:25 AM, Jan Beulich wrote:
>>>> On 25.09.14 at 21:28, <boris.ostrovsky@oracle.com> wrote:
>> @@ -389,14 +390,26 @@ static int amd_vpmu_initialise(struct vcpu *v)
>>   	 }
>>       }
>>   
>> -    ctxt = xzalloc_bytes(sizeof(struct xen_pmu_amd_ctxt) +
>> -                         2 * sizeof(uint64_t) * AMD_MAX_COUNTERS);
>> -    if ( !ctxt )
>> +    regs_size = 2 * sizeof(uint64_t) * AMD_MAX_COUNTERS;
>> +    if ( is_hvm_domain(v->domain) )
>>       {
>> -        gdprintk(XENLOG_WARNING, "Insufficient memory for PMU, "
>> -            " PMU feature is unavailable on domain %d vcpu %d.\n",
>> -            v->vcpu_id, v->domain->domain_id);
>> -        return -ENOMEM;
>> +        ctxt = xzalloc_bytes(sizeof(struct xen_pmu_amd_ctxt) + regs_size);
>> +        if ( !ctxt )
>> +        {
>> +            gdprintk(XENLOG_WARNING, "Insufficient memory for PMU, "
>> +                "PMU feature is unavailable\n");
>> +            return -ENOMEM;
>> +        }
>> +    }
>> +    else
>> +    {
>> +        if ( sizeof(struct xen_pmu_data) + regs_size > PAGE_SIZE )
> This is a compile time constant condition - no reason to issue a
> message and return failure at runtime, just BUILD_BUG_ON() instead.

It will not be if I replace AMD_MAX_COUNTERS with runtime register 
count, as you asked in an earlier comment.

-boris