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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.10.14 at 23:18, <boris.ostrovsky@xxxxxxxxxx> wrote:
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -4811,7 +4811,8 @@ static hvm_hypercall_t *const 
> pvh_hypercall64_table[NR_hypercalls] = {
>      HYPERCALL(hvm_op),
>      HYPERCALL(sysctl),
>      HYPERCALL(domctl),
> -    [ __HYPERVISOR_arch_1 ] = (hvm_hypercall_t *)paging_domctl_continuation
> +    [ __HYPERVISOR_arch_1 ] = (hvm_hypercall_t *)paging_domctl_continuation,
> +    HYPERCALL(xenpmu_op)
>  };

At least the operations visible in the patch context are all sorted
by hypercall number - please don't break this.

> +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 ...

> --- 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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