From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:50791) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SepA8-0007je-K6 for qemu-devel@nongnu.org; Wed, 13 Jun 2012 11:07:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SepA1-0004xG-DD for qemu-devel@nongnu.org; Wed, 13 Jun 2012 11:07:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:13113) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SepA1-0004vO-5c for qemu-devel@nongnu.org; Wed, 13 Jun 2012 11:07:05 -0400 Date: Wed, 13 Jun 2012 16:06:58 +0100 From: "Daniel P. Berrange" Message-ID: <20120613150658.GD29641@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> <20120608164856.GB4012@redhat.com> <20120611142205.68e86ddb@doriath.home> <20120613145355.GC29641@redhat.com> <4FD8AA58.1040700@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <4FD8AA58.1040700@redhat.com> 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: Paolo Bonzini Cc: Amit Shah , Markus Armbruster , qemu-devel@nongnu.org, Anthony Liguori , Luiz Capitulino On Wed, Jun 13, 2012 at 04:57:28PM +0200, Paolo Bonzini wrote: > Il 13/06/2012 16:53, Daniel P. Berrange ha scritto: > >>> > > 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. > >> > > >> > Can't the guest OS awake itself? > > I didn't think so. Even if it can, we can't rate limit SUSPEND > > events in isolation, because they must be strictly ordered > > wrt RESUME events. > > It can program the RTC to awake the OS, but only at 1 wakeup/second. Ah that hardware rate limit is good - we don't need todo separate throttling with this event then. 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 :|