Re: [PATCH 04/22] qemu: domain: Drop added features from migratable CPU

Features marked with added='yes' in CPU model definitions have to be removed before migration, otherwise older libvirt would complain about unknown CPU features. We only do this for features that were enabled for a given CPU model even with older libvirt, which just ignored the features. And only for features we added ourselves when updating CPU definition during domain startup, that is we do not remove features which were explicitly mentioned by a user. That said, this is not the safest thing we could do, but it's effectively the same thing we did before the affected features were added: we ignored them completely on both sides of migration.

Signed-off-by: Jiri Denemark <jdenemar(a)redhat.com&gt; --- src/qemu/qemu_domain.c | 50 ++++++++++++++++++++++++++++++-- src/qemu/qemu_domain.h | 3 +- src/qemu/qemu_migration_cookie.c | 5 +++- 3 files changed, 54 insertions(+), 4 deletions(-)

@@ -6643,10 +6644,36 @@ qemuDomainDefCopy(virQEMUDriver *driver,

+static bool +qemuDomainDropAddedCPUFeatures(const char *name, + virCPUFeaturePolicy policy G_GNUC_UNUSED, + void *opaque) +{ + qemuDomainDropAddedCPUFeaturesData *data = opaque; + + if (!g_strv_contains(data->added, name)) + return true; + + if (data->keep && g_strv_contains((const char **) data->keep, name)) + return true;

@@ -6664,6 +6691,25 @@ qemuDomainMakeCPUMigratable(virArch arch, return -1; } + if (virCPUx86GetAddedFeatures(cpu->model, &data.added) < 0) + return -1; + + /* Drop features marked as added in a cpu model, but only + * when they are not mentioned in origCPU, i.e., when they were not + * explicitly mentioned by the user. + */ + if (data.added) { + g_auto(GStrv) keep = NULL; + + if (origCPU) { + keep = virCPUDefListFeatures(origCPU); + data.keep = keep; + } + + if (virCPUDefFilterFeatures(cpu, qemuDomainDropAddedCPUFeatures, &data) < 0) + return -1;

+ }