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Thu, 25 Jul 2024 16:54:56 -0700 (PDT) Received: from wheely.local0.net ([203.220.44.216]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2cf28c7fef3sm2142060a91.16.2024.07.25.16.54.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Jul 2024 16:54:55 -0700 (PDT) From: Nicholas Piggin To: qemu-devel@nongnu.org Cc: Nicholas Piggin , qemu-ppc@nongnu.org, Harsh Prateek Bora , Anushree Mathur , Shivaprasad G Bhat , Vaibhav Jain Subject: [PULL 07/96] target/ppc: handle vcpu hotplug failure gracefully Date: Fri, 26 Jul 2024 09:52:40 +1000 Message-ID: <20240725235410.451624-8-npiggin@gmail.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240725235410.451624-1-npiggin@gmail.com> References: <20240725235410.451624-1-npiggin@gmail.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::42a; envelope-from=npiggin@gmail.com; helo=mail-pf1-x42a.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, 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 From: Harsh Prateek Bora 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 Signed-off by: Harsh Prateek Bora Reported-by: Anushree Mathur Suggested-by: Shivaprasad G Bhat Suggested-by: Vaibhav Jain Tested-by: Anushree Mathur Reviewed-by: Nicholas Piggin Signed-off-by: Nicholas Piggin --- target/ppc/kvm.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c index 2c3932200b..907dba60d1 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);