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Thu, 16 May 2024 05:32:31 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AD7012004F; Thu, 16 May 2024 05:32:29 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9B39C2004D; Thu, 16 May 2024 05:32:27 +0000 (GMT) Received: from li-1901474c-32f3-11b2-a85c-fc5ff2c001f3.ibm.com (unknown [9.79.188.146]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 16 May 2024 05:32:27 +0000 (GMT) From: Harsh Prateek Bora To: npiggin@gmail.com, qemu-ppc@nongnu.org, qemu-devel@nongnu.org Cc: danielhb413@gmail.com, vaibhav@linux.ibm.com, sbhat@linux.ibm.com, salil.mehta@huawei.com Subject: [PATCH v2 4/4] target/ppc: handle vcpu hotplug failure gracefully Date: Thu, 16 May 2024 11:02:11 +0530 Message-Id: <20240516053211.145504-5-harshpb@linux.ibm.com> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20240516053211.145504-1-harshpb@linux.ibm.com> References: <20240516053211.145504-1-harshpb@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: x_uuvj0dm4zseI3ohVxygHQX-5bz1bA3 X-Proofpoint-GUID: x8Oznjey9MFLd8ou0UZJX-KKJJmyCfYW X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.650,FMLib:17.11.176.26 definitions=2024-05-16_02,2024-05-15_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 clxscore=1015 adultscore=0 suspectscore=0 impostorscore=0 priorityscore=1501 mlxlogscore=999 mlxscore=0 malwarescore=0 phishscore=0 bulkscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2405010000 definitions=main-2405160037 Received-SPF: pass client-ip=148.163.158.5; envelope-from=harshpb@linux.ibm.com; helo=mx0b-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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.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. Based on api refactoring to create/park vcpus introduced in 1/8 of patch series: https://lore.kernel.org/qemu-devel/20240312020000.12992-2-salil.mehta@huawei.com/ 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 Signed-off by: Harsh Prateek Bora Tested-by: Anushree Mathur --- target/ppc/kvm.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c index 63930d4a77..25f0cf0ba8 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" #define PROC_DEVTREE_CPU "/proc/device-tree/cpus/" @@ -2339,6 +2341,26 @@ static void alter_insns(uint64_t *word, uint64_t flags, bool on) } } +static bool kvmppc_cpu_realize(CPUState *cs, Error **errp) +{ + int ret; + + cs->cpu_index = cpu_get_free_index(); + + POWERPC_CPU(cs)->vcpu_id = cs->cpu_index; + + if (cs->parent_obj.hotplugged) { + /* create and park to fail gracefully in case vcpu hotplug fails */ + ret = kvm_create_and_park_vcpu(cs); + if (ret) { + error_setg(errp, "%s: vcpu hotplug failed with %d", + __func__, ret); + return false; + } + } + return true; +} + static void kvmppc_host_cpu_class_init(ObjectClass *oc, void *data) { PowerPCCPUClass *pcc = POWERPC_CPU_CLASS(oc); @@ -2958,4 +2980,6 @@ void kvmppc_set_reg_tb_offset(PowerPCCPU *cpu, int64_t tb_offset) void kvm_arch_accel_class_init(ObjectClass *oc) { + AccelClass *ac = ACCEL_CLASS(oc); + ac->cpu_common_realize = kvmppc_cpu_realize; }