From 28221f9c999a9b34f58d94599da9c229df9a4fed Mon Sep 17 00:00:00 2001 From: Janosch Frank Date: Fri, 28 Sep 2018 11:34:35 +0200 Subject: [PATCH] s390x: Fence huge pages prior to 3.1 As the kernel has no way of disallowing the start of a huge page backed VM, we can migrate a running huge backed VM to a host that has no huge page KVM support. Let's glue huge page support support to the 3.1 machine, so we do not migrate to a destination host that doesn't have QEMU huge page support and can stop migration if KVM doesn't indicate support. Signed-off-by: Janosch Frank Message-Id: <20180928093435.198573-1-frankja@linux.ibm.com> Reviewed-by: David Hildenbrand Signed-off-by: Cornelia Huck --- hw/s390x/s390-virtio-ccw.c | 10 ++++++++++ include/hw/s390x/s390-virtio-ccw.h | 3 +++ target/s390x/kvm.c | 6 ++++++ 3 files changed, 19 insertions(+) diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c index f0f7fdcadd..53fd7c975f 100644 --- a/hw/s390x/s390-virtio-ccw.c +++ b/hw/s390x/s390-virtio-ccw.c @@ -456,6 +456,7 @@ static void ccw_machine_class_init(ObjectClass *oc, void *data) s390mc->ri_allowed = true; s390mc->cpu_model_allowed = true; s390mc->css_migration_enabled = true; + s390mc->hpage_1m_allowed = true; mc->init = ccw_init; mc->reset = s390_machine_reset; mc->hot_add_cpu = s390_hot_add_cpu; @@ -535,6 +536,12 @@ bool cpu_model_allowed(void) return get_machine_class()->cpu_model_allowed; } +bool hpage_1m_allowed(void) +{ + /* for "none" machine this results in true */ + return get_machine_class()->hpage_1m_allowed; +} + static char *machine_get_loadparm(Object *obj, Error **errp) { S390CcwMachineState *ms = S390_CCW_MACHINE(obj); @@ -747,6 +754,9 @@ static void ccw_machine_3_0_instance_options(MachineState *machine) static void ccw_machine_3_0_class_options(MachineClass *mc) { + S390CcwMachineClass *s390mc = S390_MACHINE_CLASS(mc); + + s390mc->hpage_1m_allowed = false; ccw_machine_3_1_class_options(mc); SET_MACHINE_COMPAT(mc, CCW_COMPAT_3_0); } diff --git a/include/hw/s390x/s390-virtio-ccw.h b/include/hw/s390x/s390-virtio-ccw.h index e9c4f4182b..8aa27199c9 100644 --- a/include/hw/s390x/s390-virtio-ccw.h +++ b/include/hw/s390x/s390-virtio-ccw.h @@ -39,12 +39,15 @@ typedef struct S390CcwMachineClass { bool ri_allowed; bool cpu_model_allowed; bool css_migration_enabled; + bool hpage_1m_allowed; } S390CcwMachineClass; /* runtime-instrumentation allowed by the machine */ bool ri_allowed(void); /* cpu model allowed by the machine */ bool cpu_model_allowed(void); +/* 1M huge page mappings allowed by the machine */ +bool hpage_1m_allowed(void); /** * Returns true if (vmstate based) migration of the channel subsystem diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c index 348e8cc546..323cb00e6a 100644 --- a/target/s390x/kvm.c +++ b/target/s390x/kvm.c @@ -292,6 +292,12 @@ static int kvm_s390_configure_mempath_backing(KVMState *s) return 0; } + if (!hpage_1m_allowed()) { + error_report("This QEMU machine does not support huge page " + "mappings"); + return -EINVAL; + } + if (path_psize != 1 * MiB) { error_report("Memory backing with 2G pages was specified, " "but KVM does not support this memory backing"); -- 2.11.4.GIT