From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 664A3606A31F for ; Fri, 30 Oct 2026 13:15:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=ATQP36M0 Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1xMmS2-0001M4-Rr; Fri, 30 Oct 2026 09:15:23 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xMmRz-0001DF-8l for qemu-devel@nongnu.org; Fri, 30 Oct 2026 09:15:20 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xMmRv-0005Pr-Ua for qemu-devel@nongnu.org; Fri, 30 Oct 2026 09:15:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1793366115; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8cxputGmZ3JXZXRm5sHq/Fjnsxhk83VtPil5rs77aNw=; b=ATQP36M0dEyYND/Yy6HPUqb48NBQtHhkQYCR8k7FqQe9UYfwtgiNTFzXZ4kko1EiesgEPB l18FE2FDdRbGMKKWX75QyyzP5FlxgJI7hBIO8db/hZjMu01OPYKZ0nFLwd7Eb5sS28m3UM PoMkupdvtnGXSimSn79epaVlwl0EIUs= 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-527-Bg953bgqOjaQ8RdG2tVCpQ-1; Fri, 30 Oct 2026 09:15:10 -0400 X-MC-Unique: Bg953bgqOjaQ8RdG2tVCpQ-1 X-Mimecast-MFC-AGG-ID: Bg953bgqOjaQ8RdG2tVCpQ_1793366108 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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 857BD1956058; Fri, 30 Oct 2026 13:15:08 +0000 (UTC) Received: from laptop.redhat.corp (headnet04.pony-001.prod.iad2.dc.redhat.com [10.2.32.116]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id BD9871956088; Fri, 30 Oct 2026 13:15:03 +0000 (UTC) From: Eric Auger To: eric.auger.pro@gmail.com, eric.auger@redhat.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org, peter.maydell@linaro.org, shaju.abraham@nutanix.com, khushit.shah@nutanix.com, richard.henderson@linaro.org, pbonzini@redhat.com, skolothumtho@nvidia.com, philmd@oss.qualcomm.com, 7746591750@163.com, maobibo@loongson.cn, harshpb@linux.ibm.com, amachhiw@linux.ibm.com, daniel.barboza@oss.qualcomm.com, milesg@linux.ibm.com, farman@linux.ibm.com, cohuck@redhat.com, alireza.sanaee@huawei.com Cc: armbru@redhat.com, mbawa@redhat.com Subject: [PATCH v4 for-11.2 10/10] target/arm/kvm: Improve error handling on scratch vcpu probe Date: Fri, 30 Oct 2026 14:13:18 +0100 Message-ID: <20261030131406.461599-11-eric.auger@redhat.com> In-Reply-To: <20261030131406.461599-1-eric.auger@redhat.com> References: <20261030131406.461599-1-eric.auger@redhat.com> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.129.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 5 X-Spam_score: 0.5 X-Spam_bar: / X-Spam_report: (0.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Pass an error handle to both kvm_arm_create_scratch_host_vcpu() and kvm_arm_get_host_cpu_features(). This allows to improve the error reporting on kvm_arm_set_cpu_features_from_host(). If any, the error is stored in the new cpu->host_cpu_probe_err field and further propagated on realize(). In arm_gic_cap_kvm_probe() call path we just pass a NULL error handle to kvm_arm_create_scratch_host_vcpu because we don't care about the failure nature and just want to revert to emulated versions if it fails. Signed-off-by: Eric Auger --- target/arm/kvm_arm.h | 3 ++- target/arm/kvm.c | 40 ++++++++++++++++++++++++++++------------ 2 files changed, 30 insertions(+), 13 deletions(-) diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h index e7c40fb003..9c7e7f654a 100644 --- a/target/arm/kvm_arm.h +++ b/target/arm/kvm_arm.h @@ -105,6 +105,7 @@ struct kvm_vcpu_init; * @init: filled in with the necessary values for creating a host * vcpu. If NULL is provided, will not init the vCPU (though the cpufd * will still be set up). + * @errp: Error handle * * Create a scratch vcpu in its own VM of the type preferred by the host * kernel (as would be used for '-cpu host'), for purposes of probing it @@ -114,7 +115,7 @@ struct kvm_vcpu_init; * false on failure (and fdarray and init are not valid). */ bool kvm_arm_create_scratch_host_vcpu(int *fdarray, - struct kvm_vcpu_init *init); + struct kvm_vcpu_init *init, Error **errp); /** * kvm_arm_destroy_scratch_host_vcpu: diff --git a/target/arm/kvm.c b/target/arm/kvm.c index f9c7577460..b66eb4f6c2 100644 --- a/target/arm/kvm.c +++ b/target/arm/kvm.c @@ -62,6 +62,7 @@ typedef struct ARMHostCPUFeatures { uint32_t target; uint32_t sve_vq_supported; const char *dtb_compatible; + Error *probe_err; } ARMHostCPUFeatures; static ARMHostCPUFeatures arm_host_cpu_features; @@ -104,13 +105,14 @@ static int kvm_arm_vcpu_finalize(ARMCPU *cpu, int feature) } bool kvm_arm_create_scratch_host_vcpu(int *fdarray, - struct kvm_vcpu_init *init) + struct kvm_vcpu_init *init, Error **errp) { int ret = 0, kvmfd = -1, vmfd = -1, cpufd = -1; int max_vm_pa_size; kvmfd = qemu_open_old("/dev/kvm", O_RDWR); if (kvmfd < 0) { + error_setg_errno(errp, errno, "Failed to open /dev/kvm"); goto err; } max_vm_pa_size = ioctl(kvmfd, KVM_CHECK_EXTENSION, KVM_CAP_ARM_VM_IPA_SIZE); @@ -121,6 +123,7 @@ bool kvm_arm_create_scratch_host_vcpu(int *fdarray, vmfd = ioctl(kvmfd, KVM_CREATE_VM, max_vm_pa_size); } while (vmfd == -1 && errno == EINTR); if (vmfd < 0) { + error_setg_errno(errp, errno, "Failed to create the scratch VM"); goto err; } @@ -140,6 +143,7 @@ bool kvm_arm_create_scratch_host_vcpu(int *fdarray, cpufd = ioctl(vmfd, KVM_CREATE_VCPU, 0); if (cpufd < 0) { + error_setg_errno(errp, errno, "Failed to create the scratch VCPU"); goto err; } @@ -153,12 +157,16 @@ bool kvm_arm_create_scratch_host_vcpu(int *fdarray, ret = ioctl(vmfd, KVM_ARM_PREFERRED_TARGET, &preferred); if (ret < 0) { + error_setg_errno(errp, errno, + "Failed to get the preferred KVM target"); goto err; } init->target = preferred.target; } ret = ioctl(cpufd, KVM_ARM_VCPU_INIT, init); if (ret < 0) { + error_setg_errno(errp, errno, + "Failed to initialize the scratch VCPU"); goto err; } @@ -312,13 +320,19 @@ static uint32_t kvm_arm_sve_get_vls(int fd) return vls[0] & MAKE_64BIT_MASK(0, ARM_MAX_VQ); } -static void kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf) +/** + * kvm_arm_get_host_cpu_features: + * @ahcf: host CPU feature struct to populate + * @errp: error handle + * + * Identify the feature bits corresponding to the host CPU by creating a + * scratch VM/vCPU and querying its ID registers. + * + * On failure, @ahcf->target is QEMU_KVM_ARM_TARGET_NONE and *errp is set + * On success, @ahcf->target is set to a valid KVM target. + */ +static void kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf, Error **errp) { - /* Identify the feature bits corresponding to the host CPU, and - * fill out the ARMHostCPUClass fields accordingly. To do this - * we have to create a scratch VM, create a single CPU inside it, - * and then query that CPU for the relevant ID registers. - */ int fdarray[3]; bool sve_supported; bool el2_supported; @@ -330,6 +344,7 @@ static void kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf) ahcf->dtb_compatible = "arm,armv8"; if (!kvm_enabled()) { + error_setg(errp, "KVM is not enabled"); return; } @@ -371,7 +386,7 @@ static void kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf) features |= 1ULL << ARM_FEATURE_PMU; } - if (!kvm_arm_create_scratch_host_vcpu(fdarray, &init)) { + if (!kvm_arm_create_scratch_host_vcpu(fdarray, &init, errp)) { return; } @@ -502,6 +517,7 @@ static void kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf) kvm_arm_destroy_scratch_host_vcpu(fdarray); if (err < 0) { + error_setg(errp, "Failed to read some host CPU ID registers"); return; } @@ -528,7 +544,8 @@ void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu) CPUARMState *env = &cpu->env; if (!arm_host_cpu_features.dtb_compatible) { - kvm_arm_get_host_cpu_features(&arm_host_cpu_features); + kvm_arm_get_host_cpu_features(&arm_host_cpu_features, + &arm_host_cpu_features.probe_err); } cpu->kvm_target = arm_host_cpu_features.target; @@ -538,8 +555,7 @@ void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu) * We can't report this error yet, so flag that we need to * in arm_cpu_realizefn(). */ - error_setg(&cpu->host_cpu_probe_err, - "failed to retrieve host CPU features"); + cpu->host_cpu_probe_err = error_copy(arm_host_cpu_features.probe_err); return; } @@ -2674,7 +2690,7 @@ void arm_gic_cap_kvm_probe(GICCapability *v2, GICCapability *v3) { int fdarray[3]; - if (!kvm_arm_create_scratch_host_vcpu(fdarray, NULL)) { + if (!kvm_arm_create_scratch_host_vcpu(fdarray, NULL, NULL)) { return; } -- 2.53.0