Re: [V12 PATCH 3/4] pvh dom0: Add and remove foreign pages

["Jan Beulich" <JBeulich@suse.com>]

>>> On 15.05.14 at 03:59, <mukesh.rathor@oracle.com> wrote:
> Code wise several options, but seems mem_event.c would be the best 
> place to put checks (would ENOSYS be more appropriate?):

I'd prefer -EOPNOTSUPP as you did.

> +++ b/xen/arch/x86/mm/mem_event.c
> @@ -538,6 +538,13 @@ int mem_event_domctl(struct domain *d, xen_domctl_mem_event
>          case XEN_DOMCTL_MEM_EVENT_OP_PAGING_ENABLE:
>          {
>              struct p2m_domain *p2m = p2m_get_hostp2m(d);
> +            struct domain *hwdom = rcu_lock_domain_by_id(hardware_domid);
> +
> +            rcu_unlock_domain(hwdom);

Why not simply look at hardware_domain? But I think that's wrong
anyway, and you want to look at current->domain instead. And
even that would still assume that a guest controlled by other than
Dom0 would only ever have operations like this carried out by its
controlling domain - i.e. perhaps you need to check both.

> BTW, how come you let these get away without "fixme" tags :).. :
> 
>             /* Only HAP is supported */
>             if ( !hap_enabled(d) )
>                 break;
> 
>             /* Currently only EPT is supported */
>             if ( !cpu_has_vmx )

I don't think I was involved in the addition of these features.

Jan