Re: [Xen-devel] [PATCH v12 for-xen-4.5 12/20] x86/VPMU: Initialize PMU for PV(H) guests

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 29.09.14 at 17:41, <boris.ostrovsky@xxxxxxxxxx> wrote:
> On 09/29/2014 11:25 AM, Jan Beulich wrote:
>>>>> On 25.09.14 at 21:28, <boris.ostrovsky@xxxxxxxxxx> 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.

For which case see the respective VMX side comment.

Jan


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