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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 <frankja@linux.ibm.com>
Message-Id: <20180928093435.198573-1-frankja@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
master
Janosch Frank 2018-09-28 11:34:35 +02:00 committed by Cornelia Huck
parent cb89b34907
commit 28221f9c99
3 changed files with 19 additions and 0 deletions
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10
hw/s390x/s390-virtio-ccw.c
View File

@ -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);
}

3
include/hw/s390x/s390-virtio-ccw.h
View File

@ -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

6
target/s390x/kvm.c
View File

@ -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");