Re: [PATCH v9 04/11] xen: evtchn: make evtchn_reset() ready for soft reset

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Jul 16, 2015 at 06:27:19PM +0200, Vitaly Kuznetsov wrote:
> We need to close all event channel so the domain performing soft reset
> will be able to open them back.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
> Changes since v8:
> - Check !d->controller_pause_count instead of pausing/unpausing the domain
>   in evtchn_reset(). [Konrad Rzeszutek Wilk]
> ---
>  xen/common/event_channel.c | 43 +++++++++++++++++++------------------------
>  xen/include/xen/event.h    |  3 +++
>  2 files changed, 22 insertions(+), 24 deletions(-)
> 
> diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
> index 7640e30..4fa1e4a 100644
> --- a/xen/common/event_channel.c
> +++ b/xen/common/event_channel.c
> @@ -981,44 +981,28 @@ int evtchn_unmask(unsigned int port)
>  }
>  
>  
> -static long evtchn_reset(evtchn_reset_t *r)
> +int evtchn_reset(struct domain *d)
>  {
> -    domid_t dom = r->dom;
> -    struct domain *d;
> -    int i, rc;
> -
> -    d = rcu_lock_domain_by_any_id(dom);
> -    if ( d == NULL )
> -        return -ESRCH;
> +    unsigned int i;
>  
> -    rc = xsm_evtchn_reset(XSM_TARGET, current->domain, d);
> -    if ( rc )
> -        goto out;
> +    if ( d != current->domain && !d->controller_pause_count )
> +        return -EINVAL;
>  
>      for ( i = 0; port_is_valid(d, i); i++ )
>          evtchn_close(d, i, 1);
>  
>      spin_lock(&d->event_lock);
>  
> -    if ( (dom == DOMID_SELF) && d->evtchn_fifo )
> +    if ( d->evtchn_fifo )
>      {
> -        /*
> -         * Guest domain called EVTCHNOP_reset with DOMID_SELF, destroying
> -         * FIFO event array and control blocks, resetting evtchn_port_ops to
> -         * evtchn_port_ops_2l.
> -         */
> +        /* Switching back to 2-level ABI. */
>          evtchn_fifo_destroy(d);
>          evtchn_2l_init(d);
>      }
>  
>      spin_unlock(&d->event_lock);
>  
> -    rc = 0;
> -
> -out:
> -    rcu_unlock_domain(d);
> -
> -    return rc;
> +    return 0;
>  }
>  
>  static long evtchn_set_priority(const struct evtchn_set_priority *set_priority)
> @@ -1143,9 +1127,20 @@ long do_event_channel_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
>  
>      case EVTCHNOP_reset: {
>          struct evtchn_reset reset;
> +        struct domain *d;
> +
>          if ( copy_from_guest(&reset, arg, 1) != 0 )
>              return -EFAULT;
> -        rc = evtchn_reset(&reset);
> +
> +        d = rcu_lock_domain_by_any_id(reset.dom);
> +        if ( d == NULL )
> +            return -ESRCH;
> +
> +        rc = xsm_evtchn_reset(XSM_TARGET, current->domain, d);
> +        if ( !rc )
> +            rc = evtchn_reset(d);
> +
> +        rcu_unlock_domain(d);
>          break;
>      }
>  
> diff --git a/xen/include/xen/event.h b/xen/include/xen/event.h
> index af923d1..b87924a 100644
> --- a/xen/include/xen/event.h
> +++ b/xen/include/xen/event.h
> @@ -126,6 +126,9 @@ void evtchn_check_pollers(struct domain *d, unsigned int port);
>  
>  void evtchn_2l_init(struct domain *d);
>  
> +/* Close all event channels and reset to 2-level ABI. */
> +int evtchn_reset(struct domain *d);
> +
>  /*
>   * Low-level event channel port ops.
>   */
> -- 
> 2.4.3
>