From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:34457) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Sd2N2-0006QC-0k for qemu-devel@nongnu.org; Fri, 08 Jun 2012 12:49:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Sd2My-0003zC-FD for qemu-devel@nongnu.org; Fri, 08 Jun 2012 12:49:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59288) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Sd2My-0003yz-71 for qemu-devel@nongnu.org; Fri, 08 Jun 2012 12:49:04 -0400 Date: Fri, 8 Jun 2012 17:48:56 +0100 From: "Daniel P. Berrange" Message-ID: <20120608164856.GB4012@redhat.com> References: <1337619593-25823-1-git-send-email-berrange@redhat.com> <1337619593-25823-4-git-send-email-berrange@redhat.com> <20120530155037.4e5d46df@doriath.home> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20120530155037.4e5d46df@doriath.home> Subject: Re: [Qemu-devel] [PATCH v2 3/3] Add rate limiting of RTC_CHANGE, BALLOON_CHANGE & WATCHDOG events Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Luiz Capitulino Cc: Amit Shah , qemu-devel@nongnu.org, Anthony Liguori , Markus Armbruster On Wed, May 30, 2012 at 03:50:37PM -0300, Luiz Capitulino wrote: > On Mon, 21 May 2012 17:59:53 +0100 > "Daniel P. Berrange" wrote: > > +/* Global, one-time initializer to configure the rate limiting > > + * and initialize state */ > > +static void monitor_protocol_event_init(void) > > +{ > > + qemu_mutex_init(&monitor_event_state_lock); > > + /* Limit RTC & BALLOON events to 1 per second */ > > + monitor_protocol_event_throttle(QEVENT_RTC_CHANGE, 1000); > > + monitor_protocol_event_throttle(QEVENT_BALLOON_CHANGE, 1000); > > + monitor_protocol_event_throttle(QEVENT_WATCHDOG, 1000); > > What about SUSPENDED and BLOCK_IO_ERROR? Couldn't the former be also > used by a malicious guest to cause a DoS? The former is already emitted > several times for virtio. This can't be used to filter BLOCK_IO_ERROR, since that event contains per-device state information. Filtering this would need to be done in the block layer, so it can done per device. I don't think SUSPEND can be used to DoS, since once the VM is in the suspend state, a monitor command is required to wake it up again before the guest OS can trigger a new suspend. > > @@ -4564,6 +4709,11 @@ static void sortcmdlist(void) > > * End: > > */ > > > > +void monitor_global_init(void) > > +{ > > It's better to call it monitor_early_init() (or monitor_init_early()). Hmm, I chose this name because wanted to make it clear that this applied to all monitor instances, vs monitor_init which is per-monitor. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|