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Tue, 18 Jun 2024 08:24:06 +0000 (GMT) Received: from smtpav03.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AB6C520065; Tue, 18 Jun 2024 08:24:04 +0000 (GMT) Received: from localhost.localdomain (unknown [9.109.242.165]) by smtpav03.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 18 Jun 2024 08:24:04 +0000 (GMT) From: Harsh Prateek Bora To: npiggin@gmail.com, pbonzini@redhat.com, qemu-ppc@nongnu.org, qemu-devel@nongnu.org Cc: danielhb413@gmail.com, vaibhav@linux.ibm.com, sbhat@linux.ibm.com Subject: [PATCH v4 3/3] target/ppc: handle vcpu hotplug failure gracefully Date: Tue, 18 Jun 2024 13:53:54 +0530 Message-ID: <20240618082354.13919-4-harshpb@linux.ibm.com> X-Mailer: git-send-email 2.45.1 In-Reply-To: <20240618082354.13919-1-harshpb@linux.ibm.com> References: <20240618082354.13919-1-harshpb@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: o0TYJjXiEf9JImlXL9U9RGN36RGlqSZL X-Proofpoint-GUID: BtRniRMfk5HmhPkwMipGMpuA_pLC4RAK X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.28.16 definitions=2024-06-18_02,2024-06-17_01,2024-05-17_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 mlxlogscore=999 priorityscore=1501 phishscore=0 impostorscore=0 adultscore=0 mlxscore=0 malwarescore=0 clxscore=1015 bulkscore=0 lowpriorityscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2405170001 definitions=main-2406180061 Received-SPF: pass client-ip=148.163.156.1; envelope-from=harshpb@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On ppc64, the PowerVM hypervisor runs with limited memory and a VCPU creation during hotplug may fail during kvm_ioctl for KVM_CREATE_VCPU, leading to termination of guest since errp is set to &error_fatal while calling kvm_init_vcpu. This unexpected behaviour can be avoided by pre-creating and parking vcpu on success or return error otherwise. This enables graceful error delivery for any vcpu hotplug failures while the guest can keep running. Also introducing KVM AccelCPUClass to init cpu_target_realize for kvm. Tested OK by repeatedly doing a hotplug/unplug of vcpus as below: #virsh setvcpus hotplug 40 #virsh setvcpus hotplug 70 error: internal error: unable to execute QEMU command 'device_add': kvmppc_cpu_realize: vcpu hotplug failed with -12 Reported-by: Anushree Mathur Suggested-by: Shivaprasad G Bhat Suggested-by: Vaibhav Jain Tested-by: Anushree Mathur Reviewed-by: Nicholas Piggin Signed-off by: Harsh Prateek Bora --- target/ppc/kvm.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c index 005f2239f3..77a3ebae22 100644 --- a/target/ppc/kvm.c +++ b/target/ppc/kvm.c @@ -48,6 +48,8 @@ #include "qemu/mmap-alloc.h" #include "elf.h" #include "sysemu/kvm_int.h" +#include "sysemu/kvm.h" +#include "hw/core/accel-cpu.h" #include CONFIG_DEVICES @@ -2346,6 +2348,30 @@ static void alter_insns(uint64_t *word, uint64_t flags, bool on) } } +static bool kvmppc_cpu_realize(CPUState *cs, Error **errp) +{ + int ret; + const char *vcpu_str = (cs->parent_obj.hotplugged == true) ? + "hotplug" : "create"; + cs->cpu_index = cpu_get_free_index(); + + POWERPC_CPU(cs)->vcpu_id = cs->cpu_index; + + /* create and park to fail gracefully in case vcpu hotplug fails */ + ret = kvm_create_and_park_vcpu(cs); + if (ret) { + /* + * This causes QEMU to terminate if initial CPU creation + * fails, and only CPU hotplug failure if the error happens + * there. + */ + error_setg(errp, "%s: vcpu %s failed with %d", + __func__, vcpu_str, ret); + return false; + } + return true; +} + static void kvmppc_host_cpu_class_init(ObjectClass *oc, void *data) { PowerPCCPUClass *pcc = POWERPC_CPU_CLASS(oc); @@ -2966,3 +2992,23 @@ void kvmppc_set_reg_tb_offset(PowerPCCPU *cpu, int64_t tb_offset) void kvm_arch_accel_class_init(ObjectClass *oc) { } + +static void kvm_cpu_accel_class_init(ObjectClass *oc, void *data) +{ + AccelCPUClass *acc = ACCEL_CPU_CLASS(oc); + + acc->cpu_target_realize = kvmppc_cpu_realize; +} + +static const TypeInfo kvm_cpu_accel_type_info = { + .name = ACCEL_CPU_NAME("kvm"), + + .parent = TYPE_ACCEL_CPU, + .class_init = kvm_cpu_accel_class_init, + .abstract = true, +}; +static void kvm_cpu_accel_register_types(void) +{ + type_register_static(&kvm_cpu_accel_type_info); +} +type_init(kvm_cpu_accel_register_types);