On 09.05.19 11:58, Christian Borntraeger wrote:
>
>
> On 02.05.19 00:31, Collin Walling wrote:
>> DIAGNOSE 0x318 (diag318) is a privileged s390x instruction that must
>> be intercepted by SIE and handled via KVM. Let's introduce some
>> functions to communicate between QEMU and KVM via ioctls. These
>> will be used to get/set the diag318 related information (also known
>> as the "Control Program Code" or "CPC"), as well as check the system
>> if KVM supports handling this instruction.
>>
>> The availability of this instruction is determined by byte 134, bit 0
>> of the Read Info block. This coincidentally expands into the space used
>> for CPU entries, which means VMs running with the diag318 capability
>> will have a reduced maximum CPU count. To alleviate this, let's calculate
>> the actual max CPU entry space by subtracting the size of Read Info from
>> the SCCB size then dividing that number by the size of a CPU entry. If
>> this value is less than the value denoted by S390_MAX_CPUS, then let's
>> reduce the max cpus for s390 from 248 to 240 in an effort to anticipate
>> this potentially happening again in the future.
>>
>> In order to simplify the migration and system reset requirements of
>> the diag318 data, let's introduce it as a device class and include
>> a VMStateDescription.
>>
>> Diag318 is reset on during modified clear and load normal.
>>
>> Signed-off-by: Collin Walling <wall...@linux.ibm.com>
>> ---
>> hw/s390x/Makefile.objs | 1 +
>> hw/s390x/diag318.c | 100
>> +++++++++++++++++++++++++++++++++++++++++++
>> hw/s390x/diag318.h | 39 +++++++++++++++++
>> hw/s390x/s390-virtio-ccw.c | 23 ++++++++++
>> hw/s390x/sclp.c | 5 +++
>> include/hw/s390x/sclp.h | 2 +
>> linux-headers/asm-s390/kvm.h | 4 ++
>> target/s390x/kvm-stub.c | 15 +++++++
>> target/s390x/kvm.c | 32 ++++++++++++++
>> target/s390x/kvm_s390x.h | 3 ++
>> 10 files changed, 224 insertions(+)
>> create mode 100644 hw/s390x/diag318.c
>> create mode 100644 hw/s390x/diag318.h
>>
>> diff --git a/hw/s390x/Makefile.objs b/hw/s390x/Makefile.objs
>> index e02ed80..93621dc 100644
>> --- a/hw/s390x/Makefile.objs
>> +++ b/hw/s390x/Makefile.objs
>> @@ -34,3 +34,4 @@ obj-$(CONFIG_KVM) += s390-stattrib-kvm.o
>> obj-y += s390-ccw.o
>> obj-y += ap-device.o
>> obj-y += ap-bridge.o
>> +obj-y += diag318.o
>> diff --git a/hw/s390x/diag318.c b/hw/s390x/diag318.c
>> new file mode 100644
>> index 0000000..94b44da
>> --- /dev/null
>> +++ b/hw/s390x/diag318.c
>> @@ -0,0 +1,100 @@
>> +/*
>> + * DIAGNOSE 0x318 functions for reset and migration
>> + *
>> + * Copyright IBM, Corp. 2019
>> + *
>> + * Authors:
>> + * Collin Walling <wall...@linux.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.
>> + */
>> +
>> +#include "hw/s390x/diag318.h"
>> +#include "qapi/error.h"
>> +#include "kvm_s390x.h"
>> +#include "sysemu/kvm.h"
>> +
>> +static int diag318_post_load(void *opaque, int version_id)
>> +{
>> + DIAG318State *d = opaque;
>> +
>> + kvm_s390_set_cpc(d->cpc);
>> +
>> + /* It is not necessary to retain a copy of the cpc after migration. */
>> + d->cpc = 0;
>
> But we also do not need to zero it out? Can't you just drop these 2 lines?
>
>
>> +
>> + return 0;
>> +}
>> +
>> +static int diag318_pre_save(void *opaque)
>> +{
>> + DIAG318State *d = opaque;
>> +
>> + kvm_s390_get_cpc(&d->cpc);
>> + return 0;
>> +}
>> +
>> +static bool diag318_needed(void *opaque)
>> +{
>> + DIAG318State *d = opaque;
>> +
>> + return d->enabled;
>> +}
>
> I would like to have a cpumodel entry that allows to disable that feature.
> And we should
> then check for this.
>
>> +
>> +const VMStateDescription vmstate_diag318 = {
>> + .name = "vmstate_diag318",
>> + .post_load = diag318_post_load,
>> + .pre_save = diag318_pre_save,
>> + .version_id = 1,
>> + .minimum_version_id = 1,
>> + .needed = diag318_needed,
>> + .fields = (VMStateField[]) {
>> + VMSTATE_UINT64(cpc, DIAG318State),
>> + VMSTATE_END_OF_LIST()
>> + }
>> +};
>> +
>> +static void s390_diag318_realize(DeviceState *dev, Error **errp)
>> +{
>> + DIAG318State *d = DIAG318(dev);
>> +
>> + if (kvm_s390_has_diag318()) {
>> + d->enabled = true;
>> + }
>
> same here -> cpumodel
> Then we can get rid of the enabled bool.
>> +}
>> +
>> +static void s390_diag318_reset(DeviceState *dev)
>> +{
>> + DIAG318State *d = DIAG318(dev);
>> +
>> + if (d->enabled) {
>> + kvm_s390_set_cpc(0);
>> + }
>> +}
>> +
>> +static void s390_diag318_class_init(ObjectClass *klass, void *data)
>> +{
>> + DeviceClass *dc = DEVICE_CLASS(klass);
>> +
>> + dc->realize = s390_diag318_realize;
>> + dc->reset = s390_diag318_reset;
>> + dc->vmsd = &vmstate_diag318;
>> + dc->hotpluggable = false;
>> + /* Reason: Set automatically during IPL */
>> + dc->user_creatable = false;
>> +}
>> +
>> +static const TypeInfo s390_diag318_info = {
>> + .class_init = s390_diag318_class_init,
>> + .parent = TYPE_DEVICE,
>> + .name = TYPE_S390_DIAG318,
>> + .instance_size = sizeof(DIAG318State),
>> +};
>> +
>> +static void s390_diag318_register_types(void)
>> +{
>> + type_register_static(&s390_diag318_info);
>> +}
>> +
>> +type_init(s390_diag318_register_types)
>> diff --git a/hw/s390x/diag318.h b/hw/s390x/diag318.h
>> new file mode 100644
>> index 0000000..c154b0a
>> --- /dev/null
>> +++ b/hw/s390x/diag318.h
>> @@ -0,0 +1,39 @@
>> +/*
>> + * DIAGNOSE 0x318 functions for reset and migration
>> + *
>> + * Copyright IBM, Corp. 2019
>> + *
>> + * Authors:
>> + * Collin Walling <wall...@linux.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 DIAG318_H
>> + #define DIAG318_H
>> +
>> +#include "qemu/osdep.h"
>> +#include "hw/qdev.h"
>> +
>> +#define TYPE_S390_DIAG318 "diag318"
>> +#define DIAG318(obj) \
>> + OBJECT_CHECK(DIAG318State, (obj), TYPE_S390_DIAG318)
>> +
>> +typedef struct DIAG318State {
>> + /*< private >*/
>> + DeviceState parent_obj;
>> +
>> + /*< public >*/
>> + uint64_t cpc;
>> + bool enabled;
>> +} DIAG318State;
>> +
>> +typedef struct DIAG318Class {
>> + /*< private >*/
>> + DeviceClass parent_class;
>> +
>> + /*< public >*/
>> +} DIAG318Class;
>> +
>> +#endif /* DIAG318_H */
>> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
>> index d11069b..44a424b 100644
>> --- a/hw/s390x/s390-virtio-ccw.c
>> +++ b/hw/s390x/s390-virtio-ccw.c
>> @@ -36,6 +36,7 @@
>> #include "cpu_models.h"
>> #include "hw/nmi.h"
>> #include "hw/s390x/tod.h"
>> +#include "hw/s390x/diag318.h"
>>
>> S390CPU *s390_cpu_addr2state(uint16_t cpu_addr)
>> {
>> @@ -92,6 +93,7 @@ static const char *const reset_dev_types[] = {
>> "s390-sclp-event-facility",
>> "s390-flic",
>> "diag288",
>> + TYPE_S390_DIAG318,
>> };
>>
>> static void subsystem_reset(void)
>> @@ -246,6 +248,17 @@ static void s390_create_sclpconsole(const char *type,
>> Chardev *chardev)
>> qdev_init_nofail(dev);
>> }
>>
>> +static void s390_init_diag318(void)
>> +{
>> + Object *new = object_new(TYPE_S390_DIAG318);
>> + DeviceState *dev = DEVICE(new);
>> +
>> + object_property_add_child(qdev_get_machine(), TYPE_S390_DIAG318,
>> + new, NULL);
>> + object_unref(new);
>> + qdev_init_nofail(dev);
>> +}
>> +
>> static void ccw_init(MachineState *machine)
>> {
>> int ret;
>> @@ -302,6 +315,8 @@ static void ccw_init(MachineState *machine)
>>
>> /* init the TOD clock */
>> s390_init_tod();
>> +
>> + s390_init_diag318();
>> }
>>
>> static void s390_cpu_plug(HotplugHandler *hotplug_dev,
>> @@ -570,6 +585,7 @@ static void machine_set_loadparm(Object *obj, const char
>> *val, Error **errp)
>> ms->loadparm[i] = ' '; /* pad right with spaces */
>> }
>> }
>> +
>> static inline void s390_machine_initfn(Object *obj)
>> {
>> object_property_add_bool(obj, "aes-key-wrap",
>> @@ -652,6 +668,13 @@ static void
>> ccw_machine_4_0_instance_options(MachineState *machine)
>>
>> static void ccw_machine_4_0_class_options(MachineClass *mc)
>> {
>> + /*
>> + * Read Info might reveal more bytes used to detect facilities, thus
>> + * reducing the number of CPU entries. Let's reduce the max CPUs by
>> + * an arbitrary number in effort to anticipate future facility bytes.
>> + */
>> + if ((SCCB_SIZE - sizeof(ReadInfo)) / sizeof(CPUEntry) < S390_MAX_CPUS)
>> + mc->max_cpus = S390_MAX_CPUS - 8;
>
> Maybe this should depend on the presence of this feature in the cpumodel?
>
>> }
>> DEFINE_CCW_MACHINE(4_0, "4.0", true);
>>
>> diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
>> index 4510a80..9cfa188 100644
>> --- a/hw/s390x/sclp.c
>> +++ b/hw/s390x/sclp.c
>> @@ -22,6 +22,7 @@
>> #include "hw/s390x/event-facility.h"
>> #include "hw/s390x/s390-pci-bus.h"
>> #include "hw/s390x/ipl.h"
>> +#include "kvm_s390x.h"
>>
>> static inline SCLPDevice *get_sclp_device(void)
>> {
>> @@ -74,6 +75,10 @@ static void read_SCP_info(SCLPDevice *sclp, SCCB *sccb)
>> s390_get_feat_block(S390_FEAT_TYPE_SCLP_CONF_CHAR_EXT,
>> read_info->conf_char_ext);
>>
>> + /* Enable diag318 for guest if KVM supports emulation */
>> + if (kvm_s390_has_diag318())
>> + read_info->fac134 = 0x80;
>
> I think we should rather make this part of the cpumodel
+1, had the same idea when skimming over this.
--
Thanks,
David / dhildenb
