Hi, On 6/26/19 3:26 PM, Andrew Jones wrote: > On Wed, Jun 26, 2019 at 09:43:09AM +0200, Auger Eric wrote: >> Hi Drew, >> >> On 6/21/19 6:34 PM, Andrew Jones wrote: >>> Add support for the query-cpu-model-expansion QMP command to Arm. We >>> do this selectively, only exposing CPU properties which represent >>> optional CPU features which the user may want to enable/disable. Also, >>> for simplicity, we restrict the list of queryable cpu models to 'max', >>> 'host', or the current type when KVM is in use, even though there >>> may exist KVM hosts where other types would also work. For example on a >>> seattle you could use 'host' for the current type, but then attempt to >>> query 'cortex-a57', which is also a valid CPU type to use with KVM on >>> seattle hosts, but that query will fail with our simplifications. This >>> shouldn't be an issue though as management layers and users have been >>> preferring the 'host' CPU type for use with KVM for quite some time. >>> Additionally, if the KVM-enabled QEMU instance running on a seattle >>> host is using the cortex-a57 CPU type, then querying 'cortex-a57' will >>> work. Finally, we only implement expansion type 'full', as Arm does not >>> yet have a "base" CPU type. Below are some example calls and results >>> (to save character clutter they're not in json, but are still json-ish >>> to give the idea) >>> >>> # expand the 'max' CPU model >>> query-cpu-model-expansion: type:full, model:{ name:max } >>> >>> return: model:{ name:max, props:{ 'aarch64': true, 'pmu': true }} >>> >>> # attempt to expand the 'max' CPU model with pmu=off >>> query-cpu-model-expansion: >>> type:full, model:{ name:max, props:{ 'pmu': false }} >>> >>> return: model:{ name:max, props:{ 'aarch64': true, 'pmu': false }} >>> >>> # attempt to expand the 'max' CPU model with aarch64=off >>> query-cpu-model-expansion: >>> type:full, model:{ name:max, props:{ 'aarch64': false }} >>> >>> error: "'aarch64' feature cannot be disabled unless KVM is enabled >>> and 32-bit EL1 is supported" >>> >>> In the last example KVM was not in use so an error was returned. >>> >>> Note1: It's possible for features to have dependencies on other >>> features. I.e. it may be possible to change one feature at a time >>> without error, but when attempting to change all features at once >>> an error could occur depending on the order they are processed. It's >>> also possible changing all at once doesn't generate an error, because >>> a feature's dependencies are satisfied with other features, but the >>> same feature cannot be changed independently without error. For these >>> reasons callers should always attempt to make their desired changes >>> all at once in order to ensure the collection is valid. >>> >>> Note2: Certainly more features may be added to the list of >>> advertised features, e.g. 'vfp' and 'neon'. The only requirement >>> is that their property set accessors fail when invalid >>> configurations are detected. For vfp we would need something like >>> >>> set_vfp() >>> { >>> if (arm_feature(env, ARM_FEATURE_AARCH64) && >>> cpu->has_vfp != cpu->has_neon) >>> error("AArch64 CPUs must have both VFP and Neon or neither") >>> >>> in its set accessor, and the same for neon, rather than doing that >>> check at realize time, which isn't executed at qmp query time. >>> >>> Signed-off-by: Andrew Jones <drjo...@redhat.com> >>> --- >>> qapi/target.json | 6 +- >>> target/arm/monitor.c | 132 +++++++++++++++++++++++++++++++++++++++++++ >>> 2 files changed, 135 insertions(+), 3 deletions(-) >>> >>> diff --git a/qapi/target.json b/qapi/target.json >>> index 1d4d54b6002e..edfa2f82b916 100644 >>> --- a/qapi/target.json >>> +++ b/qapi/target.json >>> @@ -408,7 +408,7 @@ >>> ## >>> { 'struct': 'CpuModelExpansionInfo', >>> 'data': { 'model': 'CpuModelInfo' }, >>> - 'if': 'defined(TARGET_S390X) || defined(TARGET_I386)' } >>> + 'if': 'defined(TARGET_S390X) || defined(TARGET_I386) || >>> defined(TARGET_ARM)' } >>> >>> ## >>> # @query-cpu-model-expansion: >>> @@ -433,7 +433,7 @@ >>> # query-cpu-model-expansion while using these is not advised. >>> # >>> # Some architectures may not support all expansion types. s390x supports >>> -# "full" and "static". >>> +# "full" and "static". Arm only supports "full". >>> # >>> # Returns: a CpuModelExpansionInfo. Returns an error if expanding CPU >>> models is >>> # not supported, if the model cannot be expanded, if the model >>> contains >>> @@ -447,7 +447,7 @@ >>> 'data': { 'type': 'CpuModelExpansionType', >>> 'model': 'CpuModelInfo' }, >>> 'returns': 'CpuModelExpansionInfo', >>> - 'if': 'defined(TARGET_S390X) || defined(TARGET_I386)' } >>> + 'if': 'defined(TARGET_S390X) || defined(TARGET_I386) || >>> defined(TARGET_ARM)' } >>> >>> ## >>> # @CpuDefinitionInfo: >>> diff --git a/target/arm/monitor.c b/target/arm/monitor.c >>> index 41b32b94b258..19e3120eef95 100644 >>> --- a/target/arm/monitor.c >>> +++ b/target/arm/monitor.c >>> @@ -23,7 +23,13 @@ >>> #include "qemu/osdep.h" >>> #include "hw/boards.h" >>> #include "kvm_arm.h" >>> +#include "qapi/error.h" >>> +#include "qapi/visitor.h" >>> +#include "qapi/qobject-input-visitor.h" >>> #include "qapi/qapi-commands-target.h" >>> +#include "qapi/qmp/qerror.h" >>> +#include "qapi/qmp/qdict.h" >>> +#include "qom/qom-qobject.h" >>> >>> static GICCapability *gic_cap_new(int version) >>> { >>> @@ -82,3 +88,129 @@ GICCapabilityList *qmp_query_gic_capabilities(Error >>> **errp) >>> >>> return head; >>> } >>> + >>> +static const char *cpu_model_advertised_features[] = { >>> + "aarch64", "pmu", >>> + NULL >>> +}; >>> + >>> +CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType >>> type, >>> + CpuModelInfo *model, >>> + Error **errp) >>> +{ >>> + CpuModelExpansionInfo *expansion_info; >>> + const QDict *qdict_in = NULL; >>> + QDict *qdict_out; >>> + ObjectClass *oc; >>> + Object *obj; >>> + const char *name; >>> + int i; >>> + >>> + if (type != CPU_MODEL_EXPANSION_TYPE_FULL) { >>> + error_setg(errp, "The requested expansion type is not supported."); >>> + return NULL; >>> + } >>> + >>> + if (!kvm_enabled() && !strcmp(model->name, "host")) { >>> + error_setg(errp, "The CPU definition '%s' requires KVM", >>> model->name); >>> + return NULL; >>> + } >>> + >>> + oc = cpu_class_by_name(TYPE_ARM_CPU, model->name); >>> + if (!oc) { >>> + error_setg(errp, "The CPU definition '%s' is unknown.", >>> model->name); >>> + return NULL; >>> + } >>> + >>> + if (kvm_enabled()) { >>> + const char *cpu_type = current_machine->cpu_type; >>> + int len = strlen(cpu_type) - strlen(ARM_CPU_TYPE_SUFFIX); >>> + bool supported = false; >>> + >>> + if (!strcmp(model->name, "host") || !strcmp(model->name, "max")) { >>> + /* These are kvmarm's recommended cpu types */ >>> + supported = true; >>> + } else if (strlen(model->name) == len && >>> + !strncmp(model->name, cpu_type, len)) { >>> + /* KVM is enabled and we're using this type, so it works. */ >>> + supported = true; >>> + } >>> + if (!supported) { >>> + error_setg(errp, "The CPU definition '%s' cannot " >> use model name instead of CPU definition? > > I took that wording from s390x, but maybe I prefer "The CPU type..." > better. I'll change it for v3. > >>> + "be used with KVM on this host", model->name); >> >> According to your commit mesg doesn't it mean that we fall into the >> simplification you mentionned and not necessarily that the model name >> cannot be used along with KVM? > > There's no way to know that. The simplification is meant to avoid having > to know which models will work with KVM, because most don't, but some do. > Can you suggest wording you'd prefer if you don't want to make the error > message so absolute? I think I prefer keeping it simple like this and > just saying it doesn't work. > >> >>> seattle you could use 'host' for the current type, but then attempt to >>> query 'cortex-a57', which is also a valid CPU type to use with KVM on >>> seattle hosts, but that query will fail with our simplifications >>> + return NULL; >>> + } >>> + } >>> + >>> + if (model->props) { >>> + qdict_in = qobject_to(QDict, model->props); >>> + if (!qdict_in) { >>> + error_setg(errp, QERR_INVALID_PARAMETER_TYPE, "props", "dict"); >>> + return NULL; >>> + } >>> + } >>> + >>> + obj = object_new(object_class_get_name(oc)); >>> + >>> + if (qdict_in) { >>> + Visitor *visitor; >>> + >>> + visitor = qobject_input_visitor_new(model->props); >>> + visit_start_struct(visitor, NULL, NULL, 0, errp); >>> + if (*errp) { >> Normally we shouldn't do that as errp can be NULL. see /include/qapi/error.h >> I see the same in cpu_model_from_info() by the way (s390x/cpu_models.c) >> Maybe you can guarantee that errp isn't NULL but ... > > Yeah, I know about the errp NULL thing, which is why I use local_err > elsewhere. I decided to follow s390x here though because I'm guessing > our QMP function will never be called with a NULL errp, it just > wouldn't work that way. Would you be satisfied with an assert(errp) > at the top of the function? Or should I switch all these to local_err > and then propagate? > >>> + object_unref(obj); >>> + return NULL; >>> + } >>> + >>> + i = 0; >>> + while ((name = cpu_model_advertised_features[i++]) != NULL) { >>> + if (qdict_get(qdict_in, name)) { >>> + object_property_set(obj, visitor, name, errp); >>> + if (*errp) {> + break; >> I don't really get why we don't continue here instead of break. I see >> that later we read the props back and populate the qdict_out object > > If we get an error here we're done and want to report it. If we continued > we'd lose that error with the next object_property_set() call. See a few > lines below where we free memory and return NULL due to this error.
By the way, if you were to use local_err, you could propagate them successively to errp and you wouldn't loose any of them. This would allow to report several errors at a time. Thanks Eric > >>> + } >>> + } >>> + } >>> + >>> + if (!*errp) {> + visit_check_struct(visitor, errp); >>> + } >>> + visit_end_struct(visitor, NULL); >>> + visit_free(visitor); >>> + if (*errp) { >>> + object_unref(obj); >>> + return NULL; >>> + } >>> + } >>> + >>> + expansion_info = g_new0(CpuModelExpansionInfo, 1); >>> + expansion_info->model = g_malloc0(sizeof(*expansion_info->model)); >>> + expansion_info->model->name = g_strdup(model->name); >>> + >>> + qdict_out = qdict_new(); >>> + >>> + i = 0; >>> + while ((name = cpu_model_advertised_features[i++]) != NULL) { >>> + ObjectProperty *prop = object_property_find(obj, name, NULL); >>> + if (prop) { >>> + QObject *value; >>> + >>> + assert(prop->get); >>> + value = object_property_get_qobject(obj, name, errp); >>> + assert(!*errp); >>> + >>> + qdict_put_obj(qdict_out, name, value); >>> + } >>> + } >>> + >>> + if (!qdict_size(qdict_out)) { >>> + qobject_unref(qdict_out); >>> + } else { >>> + expansion_info->model->props = QOBJECT(qdict_out); >>> + expansion_info->model->has_props = true; >>> + }> + >>> + object_unref(obj); >>> + >>> + return expansion_info; >>> +} >>> >> Thanks >> >> Eric >> >