On Wed, 26 Jun 2019 10:07:39 -0400 Collin Walling <[email protected]> wrote:
> On 6/26/19 8:33 AM, Cornelia Huck wrote: > > On Tue, 25 Jun 2019 11:17:09 -0400 > > Collin Walling <[email protected]> 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 information. > >> > >> 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. Let's reduce the maximum CPU > >> count from 248 to 247. > >> > >> 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 set to 0 during modified clear and load normal resets. > >> > >> Signed-off-by: Collin Walling <[email protected]> > >> --- > >> hw/s390x/Makefile.objs | 1 + > >> hw/s390x/diag318.c | 80 > >> +++++++++++++++++++++++++++++++++++++++++ > >> hw/s390x/diag318.h | 38 ++++++++++++++++++++ > >> hw/s390x/s390-virtio-ccw.c | 17 +++++++++ > >> hw/s390x/sclp.c | 3 ++ > >> include/hw/s390x/sclp.h | 2 ++ > >> target/s390x/cpu.h | 8 ++++- > >> target/s390x/cpu_features.c | 3 ++ > >> target/s390x/cpu_features.h | 1 + > >> target/s390x/cpu_features_def.h | 3 ++ > >> target/s390x/gen-features.c | 1 + > >> target/s390x/kvm-stub.c | 10 ++++++ > >> target/s390x/kvm.c | 29 +++++++++++++++ > >> target/s390x/kvm_s390x.h | 2 ++ > >> 14 files changed, 197 insertions(+), 1 deletion(-) > >> create mode 100644 hw/s390x/diag318.c > >> create mode 100644 hw/s390x/diag318.h > > > > (...) > > > >> diff --git a/hw/s390x/diag318.c b/hw/s390x/diag318.c > >> new file mode 100644 > >> index 0000000..0eb80fe > >> --- /dev/null > >> +++ b/hw/s390x/diag318.c > >> @@ -0,0 +1,80 @@ > >> +/* > >> + * DIAGNOSE 0x318 functions for reset and migration > >> + * > >> + * Copyright IBM, Corp. 2019 > >> + * > >> + * Authors: > >> + * Collin Walling <[email protected]> > >> + * > >> + * 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_diag318_info(d->info); > > > > Shouldn't we at least moan if something goes wrong here? > > > > What are some things that might go wrong at this point? We > should only call this if the diag318 feature is enabled. If > we try to toggle that feature on a machine that cannot support > it, the guest will fail to start, stating (paraphrased) "some > features are not available in the configuration: diag318" > > Is there some sort of issue that could arise from QEMU that I'm not > considering? The function might return an error; so I suspected that something may possibly go wrong... checking seems like good practice in general. > > >> + return 0; > >> +} > >> + > >> +static int diag318_pre_save(void *opaque) > >> +{ > >> + DIAG318State *d = opaque; > >> + > >> + kvm_s390_get_diag318_info(&d->info); > >> + return 0; > >> +} > >> + > >> +static bool diag318_needed(void *opaque) > >> +{ > >> + return s390_has_feat(S390_FEAT_DIAG318); > > > > What happens if we emulate diag 318 in tcg and set this feature bit? We > > probably don't want to call kvm_ functions in that case. > > > > I have not tested on tcg. Well, it is not implemented right now :) My point is that we should not tie this to *kvm* functions, but rather more generic functions. > > >> +} > >> + > >> +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(info, DIAG318State), > >> + VMSTATE_END_OF_LIST() > >> + } > >> +}; > >> + > >> +static void s390_diag318_reset(DeviceState *dev) > >> +{ > >> + kvm_s390_set_diag318_info(0); > > > > Same here; we probably need a s390_set_diag318_info() function that > > either calls the kvm_ function or resets some internal state. > > > > Hmm okay. I recall doing this for the TOD-clock stuff way-back. I'll > include these functions next round. Just a simple wrapper will suffice; we can then add any possible tcg stuff whenever we get around to it (or never ;) > > >> +} > >> + > >> +static void s390_diag318_class_init(ObjectClass *klass, void *data) > >> +{ > >> + DeviceClass *dc = DEVICE_CLASS(klass); > >> + > >> + dc->reset = s390_diag318_reset; > >> + dc->vmsd = &vmstate_diag318; > >> + dc->hotpluggable = false; > >> + /* Reason: Set automatically during IPL */ > > > > "Created automatically during machine instantiation" ? > > > > I like it. > > >> + 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/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c > >> index 87b2039..54230c7 100644 > >> --- a/hw/s390x/s390-virtio-ccw.c > >> +++ b/hw/s390x/s390-virtio-ccw.c > >> @@ -38,6 +38,7 @@ > >> #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) > >> { > >> @@ -94,6 +95,7 @@ static const char *const reset_dev_types[] = { > >> "s390-sclp-event-facility", > >> "s390-flic", > >> "diag288", > >> + TYPE_S390_DIAG318, > > > > This looks a bit odd, although it is not wrong :) > > > > It's cut-off here, but TYPE_VIRTUAL_CSS_BRIDGE is also in the list :) Hah, better :)
