Re: [PATCH v7 12/19] x86/VPMU: Initialize PMU for PV guests

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

On 06/11/2014 06:20 AM, Jan Beulich wrote:
>>>> On 06.06.14 at 19:40, <boris.ostrovsky@oracle.com> wrote:
>> Code for initializing/tearing down PMU for PV guests
>> ...
>> --- a/xen/arch/x86/hvm/hvm.c
>> +++ b/xen/arch/x86/hvm/hvm.c
>> @@ -4031,7 +4031,8 @@ static hvm_hypercall_t *const pvh_hypercall64_table[NR_hypercalls] = {
>>       [ __HYPERVISOR_physdev_op ]      = (hvm_hypercall_t *)hvm_physdev_op,
>>       HYPERCALL(hvm_op),
>>       HYPERCALL(sysctl),
>> -    HYPERCALL(domctl)
>> +    HYPERCALL(domctl),
>> +    HYPERCALL(xenpmu_op)
> How is this change related to the subject and description?

Yes, this is result of my eliminating PVH patch as a standalone one and 
spreading its content over other patches. I'll update the text.

>
>> +static int pvpmu_init(struct domain *d, xen_pmu_params_t *params)
>> +{
>> +    struct vcpu *v;
>> +    struct page_info *page;
>> +    uint64_t gfn = params->d.val;
>> +
>> +    if ( !params || params->vcpu >= d->max_vcpus )
>> +        return -EINVAL;
>> +
>> +    page = get_page_from_gfn(d, gfn, NULL, P2M_ALLOC);
>> +    if ( !page )
>> +        return -EINVAL;
>> +
>> +    if ( !get_page_type(page, PGT_writable_page) )
>> +    {
>> +        put_page(page);
>> +        return -EINVAL;
>> +    }
>> +
>> +    v = d->vcpu[params->vcpu];
> I'm sure I asked this before - what guarantees (now as well as
> going forward) that you get non-NULL here? Various existing
> code paths properly verify both d->vcpu and d->vcpu[...] not
> being NULL, so you should do this consistently too.

Ah, I thought you were referring to params check last time. I'll add 
vcpu checks as well.

-boris