Re: [Xen-devel] [PATCH v14 for-xen-4.5 13/21] x86/VPMU: Initialize PMU for PV(H) guests

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 10/27/2014 12:38 PM, Jan Beulich wrote:
> > +static void pvpmu_finish(struct domain *d, xen_pmu_params_t *params)
> > +{
> > +    struct vcpu *v;
> > +    uint64_t mfn;
> > +
> > +    if ( (params->vcpu >= d->max_vcpus) || (d->vcpu == NULL) ||
> > +         (d->vcpu[params->vcpu] == NULL) )
> > +        return;
> > +
> > +    v = d->vcpu[params->vcpu];
> > +    if ( v != current )
> > +        vcpu_pause(v);
> > +
> > +    if ( v->arch.vpmu.xenpmu_data )
> > +    {
> > +        mfn = domain_page_map_to_mfn(v->arch.vpmu.xenpmu_data);
> > +        ASSERT(mfn != 0);
> > +        unmap_domain_page_global(v->arch.vpmu.xenpmu_data);
> > +        put_page_and_type(mfn_to_page(mfn));
> I think you absolutely need to clear v->arch.vpmu.xenpmu_data
> here, or else another call will (likely) crash the hypervisor. Even
> more, I think this actually needs serialization (and pvpmu_init() as
> well), especially with ...
What I should do is to destroy vpmu *before* everything else. And add 
tests for VPMU_CONTEXT_ALLOCATED at a couple of entry points to 
arch-specific code (I will need to rework Intel VPMU allocation to 
happen at initialization time as opposed to current lazy allocation). 
Then noone will be touching xenpmu_data whine it's not available. 
Including pvpmu_init().
-boris

> > --- a/xen/include/xsm/dummy.h
> > +++ b/xen/include/xsm/dummy.h
> > @@ -665,6 +665,9 @@ static XSM_INLINE int xsm_pmu_op (XSM_DEFAULT_ARG struct
> > domain *d, int op)
> >       case XENPMU_feature_set:
> >       case XENPMU_feature_get:
> >           return xsm_default_action(XSM_PRIV, d, current->domain);
> > +    case XENPMU_init:
> > +    case XENPMU_finish:
> > +        return xsm_default_action(XSM_HOOK, d, current->domain);
> ... this being XSM_HOOK rather than XSM_TARGET.
>
> Jan

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