On 17.05.2017 18:26, Aurelien Jarno wrote:
> On 2017-05-17 17:35, Thomas Huth wrote:
>> Currently we only present the plain z900 feature bits to the guest,
>> but QEMU already emulates some additional features (but not all of
>> the next CPU generation, so we can not use the next CPU level as
>> default yet). Since newer Linux kernels are checking the feature bits
>> and refuse to work if a required feature is missing, we should present
>> as much of the supported features as possible when we are running
>> with the default "qemu" CPU.
>> This patch now adds the "stfle", "extended immediate" and "stckf"
>> facility bits to the "qemu" CPU, which are already supported facilities.
>> It is unfortunately still not enough to run e.g. recent Fedora kernels,
>> but at least it's a first step into the right direction.
>
> This indeed looks like a step in a good direction. At least it makes the
> recently added STFLE emulation useful :-).
>
>> Signed-off-by: Thomas Huth <th...@redhat.com>
>> ---
>> target/s390x/cpu_models.c | 29 ++++++++++++++++++++++++++---
>> 1 file changed, 26 insertions(+), 3 deletions(-)
>>
>> diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c
>> index 8d27363..18789ab 100644
>> --- a/target/s390x/cpu_models.c
>> +++ b/target/s390x/cpu_models.c
>> @@ -658,6 +658,24 @@ static void check_compatibility(const S390CPUModel
>> *max_model,
>> "available in the configuration: ");
>> }
>>
>> +/**
>> + * The base TCG CPU model "qemu" is based on the z900. However, we already
>> + * can also emulate some additional features of later CPU generations, so
>> + * we add these additional feature bits here.
>> + */
>> +static void add_qemu_cpu_model_features(S390FeatBitmap fbm)
>> +{
>> + int i, feats[] = {
>> + S390_FEAT_STFLE,
>> + S390_FEAT_EXTENDED_IMMEDIATE,
>> + S390_FEAT_STORE_CLOCK_FAST
>
> According to my list, QEMU also fully implements the following
> facilities:
>
> S390_FEAT_LONG_DISPLACEMENT
> S390_FEAT_GENERAL_INSTRUCTIONS_EXT
> S390_FEAT_EXECUTE_EXT
> S390_FEAT_STFLE_45
Ok, thanks, I'll respin and add them to the list!
>> + };
>> +
>> + for (i = 0; i < ARRAY_SIZE(feats); i++) {
>> + set_bit(feats[i], fbm);
>> + }
>> +}
>> +
>> static S390CPUModel *get_max_cpu_model(Error **errp)
>> {
>> static S390CPUModel max_model;
>> @@ -670,10 +688,11 @@ static S390CPUModel *get_max_cpu_model(Error **errp)
>> if (kvm_enabled()) {
>> kvm_s390_get_host_cpu_model(&max_model, errp);
>> } else {
>> - /* TCG emulates a z900 */
>> + /* TCG emulates a z900 (with some additional features) */
>> max_model.def = &s390_cpu_defs[0];
>> bitmap_copy(max_model.features, max_model.def->default_feat,
>> S390_FEAT_MAX);
>> + add_qemu_cpu_model_features(max_model.features);
>> }
>> if (!*errp) {
>> cached = true;
>> @@ -925,11 +944,15 @@ static void s390_host_cpu_model_initfn(Object *obj)
>>
>> static void s390_qemu_cpu_model_initfn(Object *obj)
>> {
>> + static S390CPUDef s390_qemu_cpu_defs;
>> S390CPU *cpu = S390_CPU(obj);
>>
>> cpu->model = g_malloc0(sizeof(*cpu->model));
>> - /* TCG emulates a z900 */
>> - cpu->model->def = &s390_cpu_defs[0];
>> + /* TCG emulates a z900 (with some additional features) */
>> + memcpy(&s390_qemu_cpu_defs, &s390_cpu_defs[0],
>> sizeof(s390_qemu_cpu_defs));
>> + add_qemu_cpu_model_features(s390_qemu_cpu_defs.default_feat);
>> + add_qemu_cpu_model_features(s390_qemu_cpu_defs.full_feat);
>> + cpu->model->def = &s390_qemu_cpu_defs;
>> bitmap_copy(cpu->model->features, cpu->model->def->default_feat,
>> S390_FEAT_MAX);
>> }
>
> Otherwise it looks fine to me.
>
> Reviewed-by: Aurelien Jarno <aurel...@aurel32.net>
Thanks!
Thomas
