From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8849543B496 for ; Thu, 20 Aug 2026 11:50:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787226630; cv=none; b=Rd8yKWQ+Eo+IbECVxN4k4DAGSBvm3PPOZLx2f/ZfNOCJX4b6q3w9qbytR9q5k5j6xA8Tgbv8L59kRRsCQPUn+PiQMnio3Nk4R+mGbf6FG+Z2Wkh+Vk+0+ir+VOwcPYvV8FE1J7BqXF7wpu2vKgIML4/tdZO7i6Wir6IIfdl6zvo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787226630; c=relaxed/simple; bh=HlTOhfUZuPC0RzXmjK5sMe3hbQ0K+H4zs9u5bZY7YWA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=OAdEqPORaj+THG4fFBet4Yhyg4YvY2IiH+jJf28PqJqQAwk21C/6z0mdKHxEJDlGMk9zpNPqnR2lxMGpQDSC2Sg1csTL5mUAX6fm4RDCzTKoUdH43sqKa8YhPVMcNgQBweoWUOTJe/c11KdZ6QGCi2P6BrAL/5cTrxebRTmjnWM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=BK4Azcmm; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BK4Azcmm" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1787226627; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=bvSiCvexm0vGp60WArGjDkGI0kQakkk2uBehrXtZnc0=; b=BK4AzcmmpekSdMZx61swLw7IRIAlUmp6qZfBEnxirdB+Ujq+3uQc+ubDKPKoNqU9CgsbQF WeVDX++6wnHdVwB7O0vTNb6xCX/uelxjkom6vNyO4Ef+5KsHIfBzqin2rIT8K13uCVrA+T KuyRxuRVjppc0nez+NHePWaEEQjpWdE= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-58-0xpJ89z0MzO6uic1vkL96A-1; Thu, 20 Aug 2026 07:50:23 -0400 X-MC-Unique: 0xpJ89z0MzO6uic1vkL96A-1 X-Mimecast-MFC-AGG-ID: 0xpJ89z0MzO6uic1vkL96A_1787226622 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7A7B6195605E; Thu, 20 Aug 2026 11:50:21 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.12]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 582B23001DAF; Thu, 20 Aug 2026 11:50:20 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id D962521E6920; Thu, 20 Aug 2026 13:50:17 +0200 (CEST) From: Markus Armbruster To: Eric Auger Cc: eric.auger.pro@gmail.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org, kvmarm@lists.linux.dev, peter.maydell@linaro.org, shaju.abraham@nutanix.com, khushit.shah@nutanix.com, yangjinqian1@huawei.com, cohuck@redhat.com, richard.henderson@linaro.org, sebott@redhat.com, skolothumtho@nvidia.com, philmd@oss.qualcomm.com, maz@kernel.org, oliver.upton@linux.dev, pbonzini@redhat.com, berrange@redhat.com, abologna@redhat.com, jdenemar@redhat.com Subject: Re: [RFC PATCH v7 18/18] arm-qmp-cmds: introspection for ID register props In-Reply-To: <20260726153221.24773-19-eric.auger@redhat.com> (Eric Auger's message of "Sun, 26 Jul 2026 17:29:56 +0200") References: <20260726153221.24773-1-eric.auger@redhat.com> <20260726153221.24773-19-eric.auger@redhat.com> Date: Thu, 20 Aug 2026 13:50:17 +0200 Message-ID: <878q613tae.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-MFC-PROC-ID: MWl_QrJG59DsrVXQ_QfEhwxLvzHnNisOS7i1BuOkVGY_1787226622 X-Mimecast-Originator: redhat.com Content-Type: text/plain Eric Auger writes: > From: Cornelia Huck > > Implement the capability to query available ID register values by > adding SYSREG_* options and values to the cpu model expansion for the > host model, if available. > > Excerpt: > (QEMU) query-cpu-model-expansion type=full model={"name":"host"} Is this qmp-shell? > {"return": {"model": {"name": "host", "props": {"SYSREG_ID_AA64PFR0_EL1_EL3": 1, > "SYSREG_ID_AA64ISAR2_EL1_CLRBHB": 0, "SYSREG_CTR_EL0_L1Ip": 3, > "SYSREG_MIDR_EL1_PartNum": 3407, "SYSREG_CTR_EL0_DminLine": 4, > "SYSREG_ID_AA64MMFR0_EL1_PARange": 5, "SYSREG_ID_AA64MMFR1_EL1_ECBHB": 0 > ../.. > > This allows the upper stack to detect available writable ID regs and > the "host passthrough model" values. > > It also allows to test some ID reg field values: > (QEMU) query-cpu-model-expansion type=full model={"name":"host","props":{"SYSREG_ID_AA64ISAR0_EL1_DP":0x13}} > {"error": {"class": "GenericError", "desc": "idreg SYSREG_ID_AA64ISAR0_EL1_DP set value (0x13) exceeds length of field (4)!"}} > > (QEMU) query-cpu-model-expansion type=full model={"name":"host","props":{"SYSREG_ID_AA64ISAR0_EL1_DP":0x2}} > {"error": {"class": "GenericError", "desc": "idreg SYSREG_ID_AA64ISAR0_EL1_DP set value (0x2) does not match any arch valid enum value!"}} The examples use CPU "host". Inconvenient for me, because I run into "The CPU type 'host' requires KVM" when I try to play with them myself. If you don't actually need "host" here, consider using something that works more widely, just to help reviewers. > > The following checks are performed: > - the value does not exceed the field size > - if the field is associated to enum values, the set value must be one > of those enum values > - the value is applied against a scratch vcpu making sure the setting is > not rejected for this host > > Signed-off-by: Eric Auger > Signed-off-by: Cornelia Huck > > --- > > v5 -> v6: > - add the write capability > --- > target/arm/arm-qmp-cmds.c | 98 +++++++++++++++++++++++++++++++++++++++ > 1 file changed, 98 insertions(+) > > diff --git a/target/arm/arm-qmp-cmds.c b/target/arm/arm-qmp-cmds.c > index 83ec95c290..41fefadcea 100644 > --- a/target/arm/arm-qmp-cmds.c > +++ b/target/arm/arm-qmp-cmds.c > @@ -21,6 +21,7 @@ > */ > > #include "qemu/osdep.h" > +#include "qemu/error-report.h" > #include "qemu/target-info.h" > #include "hw/core/boards.h" > #include "kvm_arm.h" > @@ -30,7 +31,10 @@ > #include "qapi/qapi-commands-machine.h" > #include "qapi/qapi-commands-misc-arm.h" > #include "qobject/qdict.h" > +#include "qobject/qnum.h" > #include "qom/qom-qobject.h" > +#include > +#include "system/kvm.h" > #include "cpu.h" > > static GICCapability *gic_cap_new(int version) > @@ -84,11 +88,14 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type, > Error **errp) > { > CpuModelExpansionInfo *expansion_info; > + ObjectPropertyIterator iter; > const QDict *qdict_in; > + ObjectProperty *idregprop; > QDict *qdict_out; > ObjectClass *oc; > Object *obj; > const char *name; > + int fdarray[3]; > int i; > > if (type != CPU_MODEL_EXPANSION_TYPE_FULL) { > @@ -133,6 +140,38 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type, > > obj = object_new(object_class_get_name(oc)); > > + if (kvm_enabled()) { > + bool pmuv3_supported = kvm_check_extension(kvm_state, KVM_CAP_ARM_PMU_V3); > + bool sve_supported = kvm_check_extension(kvm_state, KVM_CAP_ARM_SVE); > + struct kvm_vcpu_init init = { .target = -1, }; > + bool el2_supported = kvm_arm_el2_supported(); > + bool pauth_supported; > + int ret; > + > + pauth_supported = kvm_check_extension(kvm_state, KVM_CAP_ARM_PTRAUTH_ADDRESS) && > + kvm_check_extension(kvm_state, KVM_CAP_ARM_PTRAUTH_GENERIC); > + > + if (sve_supported) { > + init.features[0] |= 1 << KVM_ARM_VCPU_SVE; > + } > + if (el2_supported) { > + init.features[0] |= 1 << KVM_ARM_VCPU_HAS_EL2; > + } > + if (pauth_supported) { > + init.features[0] |= (1 << KVM_ARM_VCPU_PTRAUTH_ADDRESS | > + 1 << KVM_ARM_VCPU_PTRAUTH_GENERIC); > + } > + if (pmuv3_supported) { > + init.features[0] |= 1 << KVM_ARM_VCPU_PMU_V3; > + } > + > + ret = kvm_arm_create_scratch_host_vcpu(fdarray, &init); > + if (!ret) { > + error_setg(errp, "failing creating a scratch vcpu"); This error message feels off. I'd use something like "can't create FOO". Still bad, because it provides no clue on why. What are the possible failure modes? > + return NULL; > + } > + } > + > if (model->props) { > Visitor *visitor; > Error *err = NULL; > @@ -145,6 +184,49 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type, > } > > qdict_in = qobject_to(QDict, model->props); > + > + for (const QDictEntry *entry = qdict_first(qdict_in); > + entry != NULL; entry = qdict_next(qdict_in, entry)) { > + const char *key = qdict_entry_key(entry); > + QObject *val_obj = qdict_entry_value(entry); > + ObjectProperty *prop; > + Visitor *v; > + bool success; > + uint64_t val; > + > + prop = object_property_find(obj, key); > + if (!prop) { > + error_setg(errp, "%s does not exist!", key); Scratch the ! >From error_setg()'s contract: * The resulting message should be a single phrase, with no newline or * trailing punctuation. Is this error reachable? How? > + return NULL; > + } > + > + if (!g_str_has_prefix(key, "SYSREG_")) { > + continue; > + } > + > + /* consume the prop to avoid unexpected parameter */ > + if (!visit_type_uint64(visitor, key, &val, errp)) { > + return NULL; > + } > + > + v = qobject_input_visitor_new(val_obj); > + > + if (!object_property_set(obj, key, v, &err)) { > + error_propagate(errp, err); Pass @errp to object_property_set() and drop the error_propagate()? > + visit_free(v); > + return NULL; > + } > + > + success = kvm_idreg_write_scratch_vcpu(fdarray[2], v, key, > + prop->opaque, &err); > + if (!success) { > + error_propagate(errp, err); Likewise? > + visit_free(v); > + return NULL; > + } > + visit_free(v); > + } > + > i = 0; > while ((name = cpu_model_advertised_features[i++]) != NULL) { > if (qdict_get(qdict_in, name)) { > @@ -160,6 +242,10 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type, > if (!err) { > arm_cpu_finalize_features(ARM_CPU(obj), &err); > } > + > + if (kvm_enabled()) { > + kvm_arm_destroy_scratch_host_vcpu(fdarray); > + } > visit_end_struct(visitor, NULL); > visit_free(visitor); > if (err) { > @@ -190,6 +276,18 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type, > } > } > > + object_property_iter_init(&iter, obj); > + > + while ((idregprop = object_property_iter_next(&iter))) { > + QObject *value; > + > + if (!g_str_has_prefix(idregprop->name, "SYSREG_")) { > + continue; > + } > + value = object_property_get_qobject(obj, idregprop->name, &error_abort); > + qdict_put_obj(qdict_out, idregprop->name, value); > + } > + > if (!qdict_size(qdict_out)) { > qobject_unref(qdict_out); > } else {