From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44203) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cEcRg-0001Nv-TQ for qemu-devel@nongnu.org; Wed, 07 Dec 2016 08:39:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cEcRe-00060c-3Q for qemu-devel@nongnu.org; Wed, 07 Dec 2016 08:39:40 -0500 Received: from 5.mo179.mail-out.ovh.net ([46.105.43.140]:52606) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cEcRd-00060L-Pa for qemu-devel@nongnu.org; Wed, 07 Dec 2016 08:39:38 -0500 Received: from player732.ha.ovh.net (b7.ovh.net [213.186.33.57]) by mo179.mail-out.ovh.net (Postfix) with ESMTP id 9068F7D5D for ; Wed, 7 Dec 2016 14:39:35 +0100 (CET) Date: Wed, 7 Dec 2016 14:39:25 +0100 From: Greg Kurz Message-ID: <20161207143925.7b3a54f2@bahia> In-Reply-To: <20161206193159.GE4027@thinpad.lan.raisama.net> References: <148104617887.7699.984921868108236415.stgit@bahia.lab.toulouse-stg.fr.ibm.com> <20161206191952.GD4027@thinpad.lan.raisama.net> <20161206193159.GE4027@thinpad.lan.raisama.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC for-2.8] machine: Convert abstract typename on compat_props to subclass names List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: qemu-devel@nongnu.org, Halil Pasic , "Michael S. Tsirkin" , qemu-stable@nongnu.org, Stefan Hajnoczi , Cornelia Huck , Paolo Bonzini On Tue, 6 Dec 2016 17:31:59 -0200 Eduardo Habkost wrote: > On Tue, Dec 06, 2016 at 05:19:52PM -0200, Eduardo Habkost wrote: > > On Tue, Dec 06, 2016 at 06:50:47PM +0100, Greg Kurz wrote: > > > Since commit "9a4c0e220d8a hw/virtio-pci: fix virtio behaviour", passing > > > -device virtio-blk-pci.disable-modern=off has no effect on 2.6 machine > > > types because the internal virtio-pci.disable-modern=on compat property > > > always prevail. > > > > > > This should ideally be fixed in the qdev properties core code, but it is > > > too late in the QEMU 2.8 schedule. So this patch fixes the issue by setting > > > the compat properties for every virtio-*-pci subtypes instead of the base > > > virtio-pci type. > > > > > > Signed-off-by: Greg Kurz > > > > So, it looks like the bug is present in many other cases... > > > > I have hacked QEMU to print a warning in case the driver name in > > compat_props refer to an abstract class or a class that have any > > subclasses. The results are below: > > > > apic-common.legacy-instance-id set for abstract class > > apic-common.vapic set for abstract class > > i386-cpu.arat set for abstract class > > i386-cpu.check set for abstract class > > i386-cpu.cpuid-0xb set for abstract class > > i386-cpu.fill-mtrr-mask set for abstract class > > i386-cpu.full-cpuid-auto-level set for abstract class > > i386-cpu.l3-cache set for abstract class > > i386-cpu.pmu set for abstract class > > pci-device.command_serr_enable set for abstract class > > pci-device.rombar set for abstract class > > pci-device.x-pcie-lnksta-dllla set for abstract class > > powerpc64-cpu.pre-2.8-migration set for abstract class > > s390-skeys.migration-enabled set for abstract class > > spapr-pci-host-bridge.ddw set for superclass > > spapr-pci-host-bridge.dynamic-reconfiguration set for superclass > > spapr-pci-host-bridge.mem64_win_size set for superclass > > spapr-pci-host-bridge.mem_win_size set for superclass > > spapr-pci-host-bridge.pre-2.8-migration set for superclass > > usb-device.full-path set for abstract class > > usb-device.msos-desc set for abstract class > > virtio-pci.disable-legacy set for abstract class > > virtio-pci.disable-modern set for abstract class > > virtio-pci.migrate-extra set for abstract class > > virtio-pci.page-per-vq set for abstract class > > virtio-pci.virtio-pci-bus-master-bug-migration set for abstract class > > virtio-pci.x-disable-pcie set for abstract class > > x86_64-cpu.arat set for abstract class > > x86_64-cpu.check set for abstract class > > x86_64-cpu.cpuid-0xb set for abstract class > > x86_64-cpu.fill-mtrr-mask set for abstract class > > x86_64-cpu.full-cpuid-auto-level set for abstract class > > x86_64-cpu.l3-cache set for abstract class > > x86_64-cpu.pmu set for abstract class > > > > I believe the cases where we are likely to cause real-world bugs > > are virtio-pci and the *-cpu classes (because -cpu is translated > > to -global). > > > > I'm not sure what should be the right fix in 2.8. I am > > considering a temporary hack to translate abstract class names in > > compat_props to global properties for all subclasses, in case > > they refer to an abstract class. This way we fix the bug where > > -global doesn't override compat_props properly, but keep the > > rules for -global untouched. > > What about this? > Indeed that would have been a clever workaround but it is too late anyway. :) BTW, that makes me think about Halil's comment in another mail, even if it is not strictly related to the comapt issue (but rather because I mentioned it in the changelog of my first patch): "So I can't even tell if -global virtio-pci.disable-modern=off is even legit on the command line." And indeed, -device doesn't accept abstract classes... shouldn't -global prohibit setting properties for them ? > (untested) > > Signed-off-by: Eduardo Habkost > --- > hw/core/machine.c | 35 ++++++++++++++++++++++++++++++++--- > 1 file changed, 32 insertions(+), 3 deletions(-) > > diff --git a/hw/core/machine.c b/hw/core/machine.c > index b0fd91f..49f9007 100644 > --- a/hw/core/machine.c > +++ b/hw/core/machine.c > @@ -554,6 +554,25 @@ static void machine_class_finalize(ObjectClass *klass, void *data) > g_free(mc->name); > } > > +static void register_compat_prop(const char *driver, > + const char *property, > + const char *value) > +{ > + GlobalProperty *p = g_new0(GlobalProperty, 1); > + /* Machine compat_props must never cause errors: */ > + p->errp = &error_abort; > + p->driver = driver; > + p->property = property; > + p->value = value; > + qdev_prop_register_global(p); > +} > + > +static void machine_register_compat_for_subclass(ObjectClass *oc, void *opaque) > +{ > + GlobalProperty *p = opaque; > + register_compat_prop(object_class_get_name(oc), p->property, p->value); > +} > + > void machine_register_compat_props(MachineState *machine) > { > MachineClass *mc = MACHINE_GET_CLASS(machine); > @@ -565,10 +584,20 @@ void machine_register_compat_props(MachineState *machine) > } > > for (i = 0; i < mc->compat_props->len; i++) { > + ObjectClass *oc; > p = g_array_index(mc->compat_props, GlobalProperty *, i); > - /* Machine compat_props must never cause errors: */ > - p->errp = &error_abort; > - qdev_prop_register_global(p); > + oc = object_class_by_name(p->driver); > + if (oc && object_class_is_abstract(oc)) { > + /* temporary hack to make sure we will never override > + * globals set explicitly on -global: if an abstract class > + * is on compat_props, register globals for each of their > + * subclasses instead. > + */ > + object_class_foreach(machine_register_compat_for_subclass, > + p->driver, false, p); > + } else { > + register_compat_prop(p->driver, p->property, p->value); > + } > } > } >