From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49855) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dSCsP-0002WQ-OE for qemu-devel@nongnu.org; Mon, 03 Jul 2017 21:43:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dSCsM-0002uu-JM for qemu-devel@nongnu.org; Mon, 03 Jul 2017 21:43:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60250) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dSCsM-0002t3-AA for qemu-devel@nongnu.org; Mon, 03 Jul 2017 21:43:38 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4D00275748 for ; Tue, 4 Jul 2017 01:43:36 +0000 (UTC) Date: Tue, 4 Jul 2017 09:43:36 +0800 From: Peter Xu Message-ID: <20170704014336.GB32003@pxdev.xzpeter.org> References: <1499049848-18012-1-git-send-email-peterx@redhat.com> <1499049848-18012-3-git-send-email-peterx@redhat.com> <20170703145903.GL12152@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170703145903.GL12152@localhost.localdomain> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 2/4] vl: move global property, migrate init earlier List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: qemu-devel@nongnu.org, Laurent Vivier , Juan Quintela , "Dr . David Alan Gilbert" On Mon, Jul 03, 2017 at 11:59:03AM -0300, Eduardo Habkost wrote: > On Mon, Jul 03, 2017 at 10:44:06AM +0800, Peter Xu wrote: > > Currently drive_init_func() may call migrate_get_current() while the > > migrate object is still not ready yet at that time. Move the migratio= n > > object init earlier, along with the global properties, right after > > acceleration init. > >=20 > > This fixes a breakage for iotest 055, which caused an assertion failu= re. > >=20 > > Reported-by: Max Reitz > > Reported-by: Philippe Mathieu-Daud=C3=A9 > > Fixes: 3df663 ("migration: move only_migratable to MigrationState") > > Signed-off-by: Peter Xu > > --- > > vl.c | 24 ++++++++++++------------ > > 1 file changed, 12 insertions(+), 12 deletions(-) > >=20 > > diff --git a/vl.c b/vl.c > > index 0c497a3..2ae4313 100644 > > --- a/vl.c > > +++ b/vl.c > > @@ -4414,6 +4414,18 @@ int main(int argc, char **argv, char **envp) > > =20 > > configure_accelerator(current_machine); > > =20 > > + /* > > + * Register all the global properties, including accel propertie= s, > > + * machine properties, and user-specified ones. > > + */ > > + register_global_properties(current_machine); > > + > > + /* > > + * Migration object can only be created after global properties > > + * are applied correctly. > > + */ > > + migration_object_init(); > > + >=20 > So, things that might introduce bugs here are: > 1) Unexpected qdev_prop_register_global() calls between this place and > the original register_global_properties() call (that would now happe= n > in a different order). > 2) register_global_properties() seeing a different global property list > because it is being called earlier. > 2.1) AccelClass::global_props is statically defined and will be the > same here. Not a problem. > 2.2) MachineClass::compat_props: same as above. > 2.3) user-provided global properties: we need to ensure all > properties in the "global" QemuOpts section are already > available at this point. >=20 >=20 > To ensure (1) is not a problem, we need to check all calls for > qdev_prop_register_global(). The callers are: >=20 > * configure_rtc() > - Called very early, when parsing command-line options. Not a proble= m.[1] > * global_init_func() > * Called by user_register_global_props() > * Called by register_global_properties(). > - That's the code we're moving. Not a problem. > * QEMU_OPTION_rtc_td_hack case in main() > - Called very early, when parsing command-line options. Not a proble= m.[1] > * QEMU_OPTION_no_kvm_pit_reinjection case in main() > - Called very early, when parsing command-line options. Not a proble= m.[1] > * register_compat_prop() > * Called by machine_register_compat_props() > * Called by register_global_properties(). > - That's the code we're moving. Not a problem. > * Called by machine_register_compat_for_subclass() > * Called by machine_register_compat_props() (see above) > * Called by register_compat_props_array() > * Called by accel_register_compat_props() > * Called by register_global_properties(). > - That's the code we're moving. Not a problem. > * qdev_prop_register_global_list() > - Used only by unit test code. > * cpu_common_parse_features() > - Used when initializing CPUs, which is done much later, when > machine_run_board_init() is called (or when -device is handled by > device_init_func()). Not a problem.[2] > * x86_cpu_parse_featurestr() > - Same as above. >=20 >=20 > To ensure (2.3) is not a problem, we need to look for references to > qemu_find_opts("global") or qemu_global_opts. They are: >=20 > * user_register_global_props() > - This is the code we're moving. Not a problem. > * default_driver_check() call at main() > - This happens earlier, before the code we're moving. Not a problem. > * qemu_global_option() > - Called very early, when parsing command-line options. Not a proble= m. >=20 >=20 > So the code reordering looks OK. >=20 > Reviewed-by: Eduardo Habkost I really appreciate for such an in-depth review on this patch. >=20 >=20 > Notes about things we need to fix in the future: >=20 > [1] I think they should be replaced by qemu_global_option() calls, thou= gh. > [2] This is a fragile portion of the global property code and should be > eventually moved to the command-line parsing section of main(). Agree on both. Thanks again! --=20 Peter Xu