On Mon, Nov 11, 2019 at 09:35:37PM +0100, Jiri Denemark wrote: > The pconfig feature was enabled in QEMU by accident in 3.1.0. All other > newer versions do not support it and it was removed from the > Icelake-Server CPU model in QEMU. > > We don't normally change our CPU models even when QEMU does so to avoid > breaking migrations between different versions of libvirt. But we can > safely do so in this specific case. QEMU never supported enabling > pconfig so any domain which was able to start has pconfig disabled. > > With a small compatibility hack which explicitly disables pconfig when > CPU model equals Icelake-Server in migratable domain definition, only > one migration scenario stays broken (and there's nothing we can do about > it): from any host to a host with libvirt < 5.10.0 and QEMU > 3.1.0. > > https://bugzilla.redhat.com/show_bug.cgi?id=1749672 > > Signed-off-by: Jiri Denemark <jdenemar@xxxxxxxxxx> > --- > src/cpu_map/x86_Icelake-Server.xml | 1 - > src/qemu/qemu_domain.c | 23 +++++++++++++++++++ > src/qemu/qemu_domain.h | 3 +++ > src/qemu/qemu_migration_cookie.c | 3 +++ > .../x86_64-cpuid-Ice-Lake-Server-guest.xml | 1 - > .../x86_64-cpuid-Ice-Lake-Server-host.xml | 11 +-------- > .../x86_64-cpuid-Ice-Lake-Server-json.xml | 1 - > 7 files changed, 30 insertions(+), 13 deletions(-) > > diff --git a/src/cpu_map/x86_Icelake-Server.xml b/src/cpu_map/x86_Icelake-Server.xml > index ecd21cf5c7..a565371977 100644 > --- a/src/cpu_map/x86_Icelake-Server.xml > +++ b/src/cpu_map/x86_Icelake-Server.xml > @@ -54,7 +54,6 @@ > <feature name='pat'/> > <feature name='pcid'/> > <feature name='pclmuldq'/> > - <feature name='pconfig'/> > <feature name='pdpe1gb'/> > <feature name='pge'/> > <feature name='pku'/> > diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c > index 58a82fbd60..4a641019be 100644 > --- a/src/qemu/qemu_domain.c > +++ b/src/qemu/qemu_domain.c > @@ -8921,6 +8921,26 @@ qemuDomainDefCopy(virQEMUDriverPtr driver, > } > > > +int > +qemuDomainMakeCPUMigratable(virCPUDefPtr cpu) > +{ > + if (cpu->mode == VIR_CPU_MODE_CUSTOM && > + STREQ_NULLABLE(cpu->model, "Icelake-Server")) { This might need tweaking when we merge support for versioned CPU I presume, but not a blocker for this series as is. > + /* Originally Icelake-Server CPU model contained pconfig CPU feature. > + * It was never actually enabled and thus it was removed. To enable > + * migration to QEMU 3.1.0 (with both new and old libvirt), we > + * explicitly disable pconfig in migration XML (otherwise old libvirt > + * would think it was implicitly enabled on the source). New libvirt > + * will drop it from the XML before starting the domain on new QEMU. > + */ > + if (virCPUDefUpdateFeature(cpu, "pconfig", VIR_CPU_FEATURE_DISABLE) < 0) > + return -1; > + } > + > + return 0; > +} > + Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
