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

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 06/11/2014 06:20 AM, Jan Beulich wrote:
> > > > On 06.06.14 at 19:40, <boris.ostrovsky@xxxxxxxxxx> 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


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