| Message ID | 20170523063645.1247-1-david@gibson.dropbear.id.au (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 23/05/2017 08:36, David Gibson wrote: > As of pseries-2.7 and later, we require the total number of guest vcpus to > be a multiple of the threads-per-core. pseries-2.6 and earlier machine > types, however, are supposed to allow this for the sake of migration from > old qemu versions which allowed this. > > Unfortunately, 8149e29 "pseries: Enforce homogeneous threads-per-core" > broke this by not considering the old machine type case. This fixes it by > only applying the check when the machine type supports hotpluggable cpus. > By not-entirely-coincidence, that corresponds to the same time when we > started enforcing total threads being a multiple of threads-per-core. > > Fixes: 8149e2992f7811355cc34721b79d69d1a3a667dd > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au> > --- > hw/ppc/spapr.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c > index c92d269..bcb0e18 100644 > --- a/hw/ppc/spapr.c > +++ b/hw/ppc/spapr.c > @@ -2863,7 +2863,13 @@ static void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev, > goto out; > } > > - if (cc->nr_threads != smp_threads) { > + /* > + * In general we should have homogeneous threads-per-core, but old > + * (pre hotplug support) machine types allow the last core to have > + * reduced threads as a compatibility hack for when we allowed > + * total vcpus not a multiple of threads-per-core. > + */ > + if (mc->has_hotpluggable_cpus && (cc->nr_threads != smp_threads)) { > error_setg(errp, "invalid nr-threads %d, must be %d", > cc->nr_threads, smp_threads); > return; > Reviewed-by: Laurent Vivier <lvivier@redhat.com>
On Tue, 23 May 2017 16:36:45 +1000 David Gibson <david@gibson.dropbear.id.au> wrote: > As of pseries-2.7 and later, we require the total number of guest vcpus to > be a multiple of the threads-per-core. pseries-2.6 and earlier machine > types, however, are supposed to allow this for the sake of migration from > old qemu versions which allowed this. > > Unfortunately, 8149e29 "pseries: Enforce homogeneous threads-per-core" > broke this by not considering the old machine type case. This fixes it by > only applying the check when the machine type supports hotpluggable cpus. > By not-entirely-coincidence, that corresponds to the same time when we > started enforcing total threads being a multiple of threads-per-core. > > Fixes: 8149e2992f7811355cc34721b79d69d1a3a667dd > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au> > --- Reviewed-by: Greg Kurz <groug@kaod.org> and Tested-by: Greg Kurz <groug@kaod.org> > hw/ppc/spapr.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c > index c92d269..bcb0e18 100644 > --- a/hw/ppc/spapr.c > +++ b/hw/ppc/spapr.c > @@ -2863,7 +2863,13 @@ static void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev, > goto out; > } > > - if (cc->nr_threads != smp_threads) { > + /* > + * In general we should have homogeneous threads-per-core, but old > + * (pre hotplug support) machine types allow the last core to have > + * reduced threads as a compatibility hack for when we allowed > + * total vcpus not a multiple of threads-per-core. > + */ > + if (mc->has_hotpluggable_cpus && (cc->nr_threads != smp_threads)) { > error_setg(errp, "invalid nr-threads %d, must be %d", > cc->nr_threads, smp_threads); > return;
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index c92d269..bcb0e18 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -2863,7 +2863,13 @@ static void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev, goto out; } - if (cc->nr_threads != smp_threads) { + /* + * In general we should have homogeneous threads-per-core, but old + * (pre hotplug support) machine types allow the last core to have + * reduced threads as a compatibility hack for when we allowed + * total vcpus not a multiple of threads-per-core. + */ + if (mc->has_hotpluggable_cpus && (cc->nr_threads != smp_threads)) { error_setg(errp, "invalid nr-threads %d, must be %d", cc->nr_threads, smp_threads); return;
As of pseries-2.7 and later, we require the total number of guest vcpus to be a multiple of the threads-per-core. pseries-2.6 and earlier machine types, however, are supposed to allow this for the sake of migration from old qemu versions which allowed this. Unfortunately, 8149e29 "pseries: Enforce homogeneous threads-per-core" broke this by not considering the old machine type case. This fixes it by only applying the check when the machine type supports hotpluggable cpus. By not-entirely-coincidence, that corresponds to the same time when we started enforcing total threads being a multiple of threads-per-core. Fixes: 8149e2992f7811355cc34721b79d69d1a3a667dd Signed-off-by: David Gibson <david@gibson.dropbear.id.au> --- hw/ppc/spapr.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)