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 <gr...@kaod.org> > > 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? (untested) Signed-off-by: Eduardo Habkost <ehabk...@redhat.com> --- 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); + } } } -- 2.7.4