diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c

> index 58d4951..576b28d 100644
> --- a/xen/arch/x86/mm/p2m.c
> +++ b/xen/arch/x86/mm/p2m.c
> @@ -1514,6 +1514,13 @@ void p2m_mem_access_emulate_check(struct vcpu *v,
>      }
>  }
>
> +void p2m_altp2m_check(struct vcpu *v, const vm_event_response_t *rsp)
> +{
> +    if ( (rsp->flags & VM_EVENT_FLAG_ALTERNATE_P2M) &&
>

Please keep the check for (rsp->flags & VM_EVENT_FLAG_ALTERNATE_P2M) in
common/vm_event.c. With that you also only have to pass the altp2m_idx here.


> +         altp2m_active(v->domain) )
> +        p2m_switch_vcpu_altp2m_by_id(v, rsp->altp2m_idx);
> +}
> diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
> index 120a78a..57095d8 100644
> --- a/xen/common/vm_event.c
> +++ b/xen/common/vm_event.c
> @@ -399,6 +399,9 @@ void vm_event_resume(struct domain *d, struct
> vm_event_domain *ved)
>
>          };
>
> +        /* Check for altp2m switch */
> +        p2m_altp2m_check(v, &rsp);
>

See my comment above.

Thanks,
Tamas