From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39501) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1drpZY-00073L-G6 for qemu-devel@nongnu.org; Tue, 12 Sep 2017 14:06:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1drpZS-0002Px-K1 for qemu-devel@nongnu.org; Tue, 12 Sep 2017 14:06:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55292) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1drpZS-0002PE-BT for qemu-devel@nongnu.org; Tue, 12 Sep 2017 14:06:02 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AF6025F723 for ; Tue, 12 Sep 2017 18:06:00 +0000 (UTC) Date: Tue, 12 Sep 2017 15:05:56 -0300 From: Eduardo Habkost Message-ID: <20170912180556.GD7570@localhost.localdomain> References: <1504776162-31400-1-git-send-email-thuth@redhat.com> <20170911145344.4f2e192c@nial.brq.redhat.com> <20170911170600.145e752d@nial.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170911170600.145e752d@nial.brq.redhat.com> Subject: Re: [Qemu-devel] [PATCH] hw/core/qdev: Do not allow hot-plugging without hotplug controller List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Igor Mammedov Cc: Thomas Huth , qemu-devel@nongnu.org, Paolo Bonzini , "Michael S. Tsirkin" , Markus Armbruster , "Dr. David Alan Gilbert" , Juan Quintela On Mon, Sep 11, 2017 at 05:06:00PM +0200, Igor Mammedov wrote: > On Mon, 11 Sep 2017 16:31:39 +0200 > Thomas Huth wrote: > > > On 11.09.2017 14:53, Igor Mammedov wrote: > > > On Thu, 7 Sep 2017 11:22:42 +0200 > > > Thomas Huth wrote: > > > > > >> qdev_unplug() bails out with an assertion if the user tries to device_del > > >> a hot-plugged device that does not have a hotplug controller. Unfortunately, > > >> our devices are all marked with hotpluggable = true by default (see the > > >> device_class_init() function in qdev.c), so it currently can happen that > > >> the user runs into this situation and QEMU gets terminated unexpectedly: > > >> > > >> $ qemu-system-aarch64 -M virt -nographic -nodefaults -monitor stdio -S > > >> QEMU 2.10.50 monitor - type 'help' for more information > > >> (qemu) device_add aux-to-i2c-bridge,id=x > > >> (qemu) device_del x > > >> ** > > >> ERROR:qdev-monitor.c:872:qdev_unplug: assertion failed: (hotplug_ctrl) > > >> Aborted (core dumped) > > >> Hotplugging devices without a hotplug controller does not make much sense, > > >> so we should disallow this during the device_add process already! > > >> > > >> Suggested-by: Paolo Bonzini > > >> Signed-off-by: Thomas Huth > > >> --- > > >> hw/core/qdev.c | 5 +++++ > > >> 1 file changed, 5 insertions(+) > > >> > > >> diff --git a/hw/core/qdev.c b/hw/core/qdev.c > > >> index 606ab53..d9ccce6 100644 > > >> --- a/hw/core/qdev.c > > >> +++ b/hw/core/qdev.c > > >> @@ -908,6 +908,11 @@ static void device_set_realized(Object *obj, bool value, Error **errp) > > >> if (local_err != NULL) { > > >> goto fail; > > >> } > > >> + } else if (dev->hotplugged) { > > >> + /* Hot-plugged device without hotplug controller? No way! */ > > >> + error_setg(&local_err, QERR_DEVICE_NO_HOTPLUG, > > >> + object_get_typename(obj)); > > >> + goto fail; > > >> } > > >> > > >> if (dc->realize) { > > > > > > maybe it should be other way around, i.e, fix device so that following would work > > > > > > device_set_realized() > > > if (dev->hotplugged && !dc->hotpluggable) { > > > error_setg(errp, QERR_DEVICE_NO_HOTPLUG, object_get_typename(obj)); > > > return; > > > } > > > > > > instead of leaving device broken, like in yours > > > 84ebd3e watchdog/wdt_diag288: Mark diag288 watchdog as non-hotpluggable > > > > No, that apparently does not work right for new devices since people > > keep forgetting to set hotpluggable = false there. Both, Paolo and Peter > > suggested that we should not allow hot-plugging if there's no hot plug > > controller - it indeed does not make sense, so we should not allow it. > historically all devices were hotpluggble and conversion to hotplug > controller didn't fix it which os fine as far as user did not attempt > unreasonable things. However it should be fixedfor code to work correctly. > > I'd suggest to flip default > dc->hotpluggable = false; > and set it to true explicitly for devices that support hotplug, > it obviously harder to do than this patch as it requires audit > of all devices, but it looks more correct than fixing symptoms of > incorrectly set dc->hotpluggable property. I agree we should do this. If we have any device-type that is not hotpluggable on any machine because no machine will return a hotplug controller for it, we shouldn't report it as hotpluggable through QMP and HMP. But this patch also seems to be required, for cases where not all machine-types accept hotplug of a given device type. -- Eduardo