qemu/include/hw/s390x/s390-virtio-ccw.h
Christian Borntraeger 0280b3eb7c s390x/kvm: use cpu model for gscb on compat machines
Starting a guest with
   <os>
    <type arch='s390x' machine='s390-ccw-virtio-2.9'>hvm</type>
  </os>
  <cpu mode='host-model'/>

on an IBM z14 results in

"qemu-system-s390x: Some features requested in the CPU model are not
available in the configuration: gs"

This is because guarded storage is fenced for compat machines that did
not have guarded storage support. While this prevents future migration
abort (by not starting the guest at all), not being able to start a
"host-model" guest is very much unexpected.  As it turns out, even if we
would modify libvirt to not expand the cpu model to contain "gs" for
compat machines, it cannot guarantee that a migration will succeed. For
example if the kernel changes its features (or the user has nested=1 on
one host but not on the other) the migration will fail nevertheless.  So
instead of fencing "gs" for machines <= 2.9 lets allow it for all
machine types that support the CPU model. This will make "host-model"
runnable all the time, while relying on the CPU model to reject invalid
migration attempts. We also need to change the migration for guarded
storage.
Additional discussions about host-model are still pending but are out
of scope of this patch.

Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Cornelia Huck <Cornelia Huck <cohuck@redhat.com>
Acked-by: Halil Pasic <pasic@linux.vnet.ibm.com>
2017-10-30 09:03:45 +01:00

59 lines
1.4 KiB
C

/*
* virtio ccw machine definitions
*
* Copyright 2012, 2016 IBM Corp.
* Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or (at
* your option) any later version. See the COPYING file in the top-level
* directory.
*/
#ifndef HW_S390X_S390_VIRTIO_CCW_H
#define HW_S390X_S390_VIRTIO_CCW_H
#include "hw/boards.h"
#define TYPE_S390_CCW_MACHINE "s390-ccw-machine"
#define S390_CCW_MACHINE(obj) \
OBJECT_CHECK(S390CcwMachineState, (obj), TYPE_S390_CCW_MACHINE)
#define S390_MACHINE_CLASS(klass) \
OBJECT_CLASS_CHECK(S390CcwMachineClass, (klass), TYPE_S390_CCW_MACHINE)
typedef struct S390CcwMachineState {
/*< private >*/
MachineState parent_obj;
/*< public >*/
bool aes_key_wrap;
bool dea_key_wrap;
uint8_t loadparm[8];
bool s390_squash_mcss;
} S390CcwMachineState;
typedef struct S390CcwMachineClass {
/*< private >*/
MachineClass parent_class;
/*< public >*/
bool ri_allowed;
bool cpu_model_allowed;
bool css_migration_enabled;
} S390CcwMachineClass;
/* runtime-instrumentation allowed by the machine */
bool ri_allowed(void);
/* cpu model allowed by the machine */
bool cpu_model_allowed(void);
/**
* Returns true if (vmstate based) migration of the channel subsystem
* is enabled, false if it is disabled.
*/
bool css_migration_enabled(void);
void subsystem_reset(void);
#endif