| Message ID | 20230911205232.71735-1-walling@linux.ibm.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v1,1/2] target/s390x: introduce "host-recommended" option for model expansion | expand |
On 11.09.23 22:52, Collin Walling wrote: Patch subject is wrong (should contain "static-recommended") > Newer S390 machines may drop support for features completely, rendering > guests operating with older CPU models incapable of running on said > machines. A manual effort to disable certain CPU features would be > required. > > To alleviate this issue, a list of "deprecated" features are now > retained within QEMU, and a new "static-recommended" CPU model expansion > type has been created to allow a query of the host-model with deprecated > features explicitly disabled. > > Signed-off-by: Collin Walling <walling@linux.ibm.com> > --- > qapi/machine-target.json | 8 +++++++- > target/s390x/cpu_features.c | 14 ++++++++++++++ > target/s390x/cpu_features.h | 1 + > target/s390x/cpu_models_sysemu.c | 26 +++++++++++++++++++++----- > 4 files changed, 43 insertions(+), 6 deletions(-) > > diff --git a/qapi/machine-target.json b/qapi/machine-target.json > index f0a6b72414..4dc891809d 100644 > --- a/qapi/machine-target.json > +++ b/qapi/machine-target.json > @@ -42,6 +42,12 @@ > # to be migration-safe, but allows tooling to get an insight and > # work with model details. > # > +# @static-recommended: Expand to a static CPU model with property > +# changes suggested by the architecture. This is useful for > +# expanding a CPU model expected to operate in mixed > +# CPU-generation environments. The @static-recommended CPU > +# models are migration-safe. > +# Can we instead make this a new parameter for query-cpu-model-expansion ("no-deprecated-features" ? ), that properly gets rejected from other archs when not supported? [...] > /* convert S390CPUDef into a static CpuModelInfo */ > static void cpu_info_from_model(CpuModelInfo *info, const S390CPUModel *model, > - bool delta_changes) > + bool delta_changes, bool disable_dep_feats) "dep" can be misleading ("depended") "no_deprecated_feat" ?
On 9/12/23 02:57, David Hildenbrand wrote: > On 11.09.23 22:52, Collin Walling wrote: > > Patch subject is wrong (should contain "static-recommended") > >> Newer S390 machines may drop support for features completely, rendering >> guests operating with older CPU models incapable of running on said >> machines. A manual effort to disable certain CPU features would be >> required. >> >> To alleviate this issue, a list of "deprecated" features are now >> retained within QEMU, and a new "static-recommended" CPU model expansion >> type has been created to allow a query of the host-model with deprecated >> features explicitly disabled. >> >> Signed-off-by: Collin Walling <walling@linux.ibm.com> >> --- >> qapi/machine-target.json | 8 +++++++- >> target/s390x/cpu_features.c | 14 ++++++++++++++ >> target/s390x/cpu_features.h | 1 + >> target/s390x/cpu_models_sysemu.c | 26 +++++++++++++++++++++----- >> 4 files changed, 43 insertions(+), 6 deletions(-) >> >> diff --git a/qapi/machine-target.json b/qapi/machine-target.json >> index f0a6b72414..4dc891809d 100644 >> --- a/qapi/machine-target.json >> +++ b/qapi/machine-target.json >> @@ -42,6 +42,12 @@ >> # to be migration-safe, but allows tooling to get an insight and >> # work with model details. >> # >> +# @static-recommended: Expand to a static CPU model with property >> +# changes suggested by the architecture. This is useful for >> +# expanding a CPU model expected to operate in mixed >> +# CPU-generation environments. The @static-recommended CPU >> +# models are migration-safe. >> +# > > Can we instead make this a new parameter for query-cpu-model-expansion > ("no-deprecated-features" ? ), that properly gets rejected from other > archs when not supported? > > [...] > So instead of a "type": "static-recommended" add an entirely new (optional) parameter key-value to the command? "disable-deprecated-features": "true|false"? >> /* convert S390CPUDef into a static CpuModelInfo */ >> static void cpu_info_from_model(CpuModelInfo *info, const S390CPUModel *model, >> - bool delta_changes) >> + bool delta_changes, bool disable_dep_feats) > > "dep" can be misleading ("depended") > > "no_deprecated_feat" ? > > Good call. Tricky one to short-hand :) With respect to labeling this as "no-deprecated-features", I think that may also be misleading: it sounds like an exclusion, when in fact we *want* the deprecated feats to show up paired with the false value. So I think "disable-deprecated-features" is a better label. Would you agree?
diff --git a/qapi/machine-target.json b/qapi/machine-target.json index f0a6b72414..4dc891809d 100644 --- a/qapi/machine-target.json +++ b/qapi/machine-target.json @@ -42,6 +42,12 @@ # to be migration-safe, but allows tooling to get an insight and # work with model details. # +# @static-recommended: Expand to a static CPU model with property +# changes suggested by the architecture. This is useful for +# expanding a CPU model expected to operate in mixed +# CPU-generation environments. The @static-recommended CPU +# models are migration-safe. +# # Note: When a non-migration-safe CPU model is expanded in static # mode, some features enabled by the CPU model may be omitted, # because they can't be implemented by a static CPU model @@ -55,7 +61,7 @@ # Since: 2.8 ## { 'enum': 'CpuModelExpansionType', - 'data': [ 'static', 'full' ] } + 'data': [ 'static', 'full', 'static-recommended' ] } ## # @CpuModelCompareResult: diff --git a/target/s390x/cpu_features.c b/target/s390x/cpu_features.c index d28eb65845..efafc9711c 100644 --- a/target/s390x/cpu_features.c +++ b/target/s390x/cpu_features.c @@ -212,6 +212,20 @@ void s390_feat_bitmap_to_ascii(const S390FeatBitmap features, void *opaque, }; } +void s390_get_deprecated_features(S390FeatBitmap features) +{ + static const int feats[] = { + /* CSSKE is deprecated on newer generations */ + S390_FEAT_CONDITIONAL_SSKE, + S390_FEAT_BPB, + }; + int i; + + for (i = 0; i < ARRAY_SIZE(feats); i++) { + set_bit(feats[i], features); + } +} + #define FEAT_GROUP_INIT(_name, _group, _desc) \ { \ .name = _name, \ diff --git a/target/s390x/cpu_features.h b/target/s390x/cpu_features.h index 87463f064d..5421762db5 100644 --- a/target/s390x/cpu_features.h +++ b/target/s390x/cpu_features.h @@ -68,6 +68,7 @@ void s390_add_from_feat_block(S390FeatBitmap features, S390FeatType type, uint8_t *data); void s390_feat_bitmap_to_ascii(const S390FeatBitmap features, void *opaque, void (*fn)(const char *name, void *opaque)); +void s390_get_deprecated_features(S390FeatBitmap features); /* Definition of a CPU feature group */ typedef struct { diff --git a/target/s390x/cpu_models_sysemu.c b/target/s390x/cpu_models_sysemu.c index 63981bf36b..1aa3d076b4 100644 --- a/target/s390x/cpu_models_sysemu.c +++ b/target/s390x/cpu_models_sysemu.c @@ -176,7 +176,7 @@ static void qdict_add_enabled_feat(const char *name, void *opaque) /* convert S390CPUDef into a static CpuModelInfo */ static void cpu_info_from_model(CpuModelInfo *info, const S390CPUModel *model, - bool delta_changes) + bool delta_changes, bool disable_dep_feats) { QDict *qdict = qdict_new(); S390FeatBitmap bitmap; @@ -198,6 +198,13 @@ static void cpu_info_from_model(CpuModelInfo *info, const S390CPUModel *model, if (!bitmap_empty(bitmap, S390_FEAT_MAX)) { s390_feat_bitmap_to_ascii(bitmap, qdict, qdict_add_enabled_feat); } + + /* features flagged as deprecated */ + if (disable_dep_feats) { + bitmap_zero(bitmap, S390_FEAT_MAX); + s390_get_deprecated_features(bitmap); + s390_feat_bitmap_to_ascii(bitmap, qdict, qdict_add_disabled_feat); + } } else { /* expand all features */ s390_feat_bitmap_to_ascii(model->features, qdict, @@ -221,6 +228,7 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type, CpuModelExpansionInfo *expansion_info = NULL; S390CPUModel s390_model; bool delta_changes = false; + bool disable_dep_feats = false; /* convert it to our internal representation */ cpu_model_from_info(&s390_model, model, &err); @@ -229,9 +237,16 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type, return NULL; } - if (type == CPU_MODEL_EXPANSION_TYPE_STATIC) { + switch (type) { + case CPU_MODEL_EXPANSION_TYPE_STATIC_RECOMMENDED: + disable_dep_feats = true; + /* fall through */ + case CPU_MODEL_EXPANSION_TYPE_STATIC: delta_changes = true; - } else if (type != CPU_MODEL_EXPANSION_TYPE_FULL) { + break; + case CPU_MODEL_EXPANSION_TYPE_FULL: + break; + default: error_setg(errp, "The requested expansion type is not supported."); return NULL; } @@ -239,7 +254,8 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type, /* convert it back to a static representation */ expansion_info = g_new0(CpuModelExpansionInfo, 1); expansion_info->model = g_malloc0(sizeof(*expansion_info->model)); - cpu_info_from_model(expansion_info->model, &s390_model, delta_changes); + cpu_info_from_model(expansion_info->model, &s390_model, + delta_changes, disable_dep_feats); return expansion_info; } @@ -388,7 +404,7 @@ CpuModelBaselineInfo *qmp_query_cpu_model_baseline(CpuModelInfo *infoa, baseline_info = g_new0(CpuModelBaselineInfo, 1); baseline_info->model = g_malloc0(sizeof(*baseline_info->model)); - cpu_info_from_model(baseline_info->model, &model, true); + cpu_info_from_model(baseline_info->model, &model, true, false); return baseline_info; }
Newer S390 machines may drop support for features completely, rendering guests operating with older CPU models incapable of running on said machines. A manual effort to disable certain CPU features would be required. To alleviate this issue, a list of "deprecated" features are now retained within QEMU, and a new "static-recommended" CPU model expansion type has been created to allow a query of the host-model with deprecated features explicitly disabled. Signed-off-by: Collin Walling <walling@linux.ibm.com> --- qapi/machine-target.json | 8 +++++++- target/s390x/cpu_features.c | 14 ++++++++++++++ target/s390x/cpu_features.h | 1 + target/s390x/cpu_models_sysemu.c | 26 +++++++++++++++++++++----- 4 files changed, 43 insertions(+), 6 deletions(-)