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Fri, 22 Mar 2024 08:15:13 +0000 (GMT) Message-ID: Date: Fri, 22 Mar 2024 13:45:10 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V8 1/8] accel/kvm: Extract common KVM vCPU {creation, parking} code To: Salil Mehta , qemu-devel@nongnu.org, qemu-arm@nongnu.org Cc: maz@kernel.org, jean-philippe@linaro.org, jonathan.cameron@huawei.com, lpieralisi@kernel.org, peter.maydell@linaro.org, richard.henderson@linaro.org, imammedo@redhat.com, andrew.jones@linux.dev, david@redhat.com, philmd@linaro.org, eric.auger@redhat.com, oliver.upton@linux.dev, pbonzini@redhat.com, mst@redhat.com, will@kernel.org, gshan@redhat.com, rafael@kernel.org, alex.bennee@linaro.org, linux@armlinux.org.uk, darren@os.amperecomputing.com, ilkka@os.amperecomputing.com, vishnu@os.amperecomputing.com, karl.heubaum@oracle.com, miguel.luis@oracle.com, salil.mehta@opnsrc.net, zhukeqian1@huawei.com, wangxiongfeng2@huawei.com, wangyanan55@huawei.com, jiakernel2@gmail.com, maobibo@loongson.cn, lixianglai@loongson.cn, linuxarm@huawei.com, Vaibhav Jain , sbhat@linux.ibm.com References: <20240312020000.12992-1-salil.mehta@huawei.com> <20240312020000.12992-2-salil.mehta@huawei.com> Content-Language: en-US From: Harsh Prateek Bora In-Reply-To: <20240312020000.12992-2-salil.mehta@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: tsxhMhWsrL_GhKz9GU4yVSscVlmqQIFx X-Proofpoint-GUID: AZ1Q4nW4o_OTiYwPeOE_BYR2DaNpe9Ki X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-03-22_04,2024-03-21_02,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 bulkscore=0 mlxlogscore=999 clxscore=1011 priorityscore=1501 mlxscore=0 malwarescore=0 impostorscore=0 spamscore=0 phishscore=0 lowpriorityscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2403210000 definitions=main-2403220058 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org + Vaibhav, Shiva Hi Salil, I came across your patch while trying to solve a related problem on spapr. One query below .. On 3/12/24 07:29, Salil Mehta via wrote: > KVM vCPU creation is done once during the vCPU realization when Qemu vCPU thread > is spawned. This is common to all the architectures as of now. > > Hot-unplug of vCPU results in destruction of the vCPU object in QOM but the > corresponding KVM vCPU object in the Host KVM is not destroyed as KVM doesn't > support vCPU removal. Therefore, its representative KVM vCPU object/context in > Qemu is parked. > > Refactor architecture common logic so that some APIs could be reused by vCPU > Hotplug code of some architectures likes ARM, Loongson etc. Update new/old APIs > with trace events instead of DPRINTF. No functional change is intended here. > > Signed-off-by: Salil Mehta > Reviewed-by: Gavin Shan > Tested-by: Vishnu Pajjuri > Reviewed-by: Jonathan Cameron > Tested-by: Xianglai Li > Tested-by: Miguel Luis > Reviewed-by: Shaoqin Huang > --- > accel/kvm/kvm-all.c | 64 ++++++++++++++++++++++++++++++++---------- > accel/kvm/trace-events | 5 +++- > include/sysemu/kvm.h | 16 +++++++++++ > 3 files changed, 69 insertions(+), 16 deletions(-) > > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c > index a8cecd040e..3bc3207bda 100644 > --- a/accel/kvm/kvm-all.c > +++ b/accel/kvm/kvm-all.c > @@ -126,6 +126,7 @@ static QemuMutex kml_slots_lock; > #define kvm_slots_unlock() qemu_mutex_unlock(&kml_slots_lock) > > static void kvm_slot_init_dirty_bitmap(KVMSlot *mem); > +static int kvm_get_vcpu(KVMState *s, unsigned long vcpu_id); > > static inline void kvm_resample_fd_remove(int gsi) > { > @@ -314,14 +315,53 @@ err: > return ret; > } > > +void kvm_park_vcpu(CPUState *cpu) > +{ > + struct KVMParkedVcpu *vcpu; > + > + trace_kvm_park_vcpu(cpu->cpu_index, kvm_arch_vcpu_id(cpu)); > + > + vcpu = g_malloc0(sizeof(*vcpu)); > + vcpu->vcpu_id = kvm_arch_vcpu_id(cpu); > + vcpu->kvm_fd = cpu->kvm_fd; > + QLIST_INSERT_HEAD(&kvm_state->kvm_parked_vcpus, vcpu, node); > +} > + > +int kvm_create_vcpu(CPUState *cpu) > +{ > + unsigned long vcpu_id = kvm_arch_vcpu_id(cpu); > + KVMState *s = kvm_state; > + int kvm_fd; > + > + trace_kvm_create_vcpu(cpu->cpu_index, kvm_arch_vcpu_id(cpu)); > + > + /* check if the KVM vCPU already exist but is parked */ > + kvm_fd = kvm_get_vcpu(s, vcpu_id); > + if (kvm_fd < 0) { > + /* vCPU not parked: create a new KVM vCPU */ > + kvm_fd = kvm_vm_ioctl(s, KVM_CREATE_VCPU, vcpu_id); > + if (kvm_fd < 0) { > + error_report("KVM_CREATE_VCPU IOCTL failed for vCPU %lu", vcpu_id); > + return kvm_fd; > + } > + } > + > + cpu->kvm_fd = kvm_fd; > + cpu->kvm_state = s; > + cpu->vcpu_dirty = true; > + cpu->dirty_pages = 0; > + cpu->throttle_us_per_full = 0; > + > + return 0; > +} > + > static int do_kvm_destroy_vcpu(CPUState *cpu) > { > KVMState *s = kvm_state; > long mmap_size; > - struct KVMParkedVcpu *vcpu = NULL; > int ret = 0; > > - trace_kvm_destroy_vcpu(); > + trace_kvm_destroy_vcpu(cpu->cpu_index, kvm_arch_vcpu_id(cpu)); > > ret = kvm_arch_destroy_vcpu(cpu); > if (ret < 0) { > @@ -347,10 +387,7 @@ static int do_kvm_destroy_vcpu(CPUState *cpu) > } > } > > - vcpu = g_malloc0(sizeof(*vcpu)); > - vcpu->vcpu_id = kvm_arch_vcpu_id(cpu); > - vcpu->kvm_fd = cpu->kvm_fd; > - QLIST_INSERT_HEAD(&kvm_state->kvm_parked_vcpus, vcpu, node); > + kvm_park_vcpu(cpu); > err: > return ret; > } > @@ -371,6 +408,8 @@ static int kvm_get_vcpu(KVMState *s, unsigned long vcpu_id) > if (cpu->vcpu_id == vcpu_id) { > int kvm_fd; > > + trace_kvm_get_vcpu(vcpu_id); > + > QLIST_REMOVE(cpu, node); > kvm_fd = cpu->kvm_fd; > g_free(cpu); > @@ -378,7 +417,7 @@ static int kvm_get_vcpu(KVMState *s, unsigned long vcpu_id) > } > } > > - return kvm_vm_ioctl(s, KVM_CREATE_VCPU, (void *)vcpu_id); > + return -ENOENT; > } > > int kvm_init_vcpu(CPUState *cpu, Error **errp) > @@ -389,19 +428,14 @@ int kvm_init_vcpu(CPUState *cpu, Error **errp) > > trace_kvm_init_vcpu(cpu->cpu_index, kvm_arch_vcpu_id(cpu)); > > - ret = kvm_get_vcpu(s, kvm_arch_vcpu_id(cpu)); > + ret = kvm_create_vcpu(cpu); > if (ret < 0) { > - error_setg_errno(errp, -ret, "kvm_init_vcpu: kvm_get_vcpu failed (%lu)", > + error_setg_errno(errp, -ret, > + "kvm_init_vcpu: kvm_create_vcpu failed (%lu)", > kvm_arch_vcpu_id(cpu)); If a vcpu hotplug fails due to failure with kvm_create_vcpu ioctl, current behaviour would be to bring down the guest as errp is &error_fatal. Any thoughts on how do we ensure that a failure with kvm_create_vcpu ioctl for hotplugged cpus (only) doesnt bring down the guest and fail gracefully (by reporting error to user on monitor?)? regards, Harsh > goto err; > } > > - cpu->kvm_fd = ret; > - cpu->kvm_state = s; > - cpu->vcpu_dirty = true; > - cpu->dirty_pages = 0; > - cpu->throttle_us_per_full = 0; > - > mmap_size = kvm_ioctl(s, KVM_GET_VCPU_MMAP_SIZE, 0); > if (mmap_size < 0) { > ret = mmap_size; > diff --git a/accel/kvm/trace-events b/accel/kvm/trace-events > index a25902597b..5558cff0dc 100644 > --- a/accel/kvm/trace-events > +++ b/accel/kvm/trace-events > @@ -9,6 +9,10 @@ kvm_device_ioctl(int fd, int type, void *arg) "dev fd %d, type 0x%x, arg %p" > kvm_failed_reg_get(uint64_t id, const char *msg) "Warning: Unable to retrieve ONEREG %" PRIu64 " from KVM: %s" > kvm_failed_reg_set(uint64_t id, const char *msg) "Warning: Unable to set ONEREG %" PRIu64 " to KVM: %s" > kvm_init_vcpu(int cpu_index, unsigned long arch_cpu_id) "index: %d id: %lu" > +kvm_create_vcpu(int cpu_index, unsigned long arch_cpu_id) "index: %d id: %lu" > +kvm_get_vcpu(unsigned long arch_cpu_id) "id: %lu" > +kvm_destroy_vcpu(int cpu_index, unsigned long arch_cpu_id) "index: %d id: %lu" > +kvm_park_vcpu(int cpu_index, unsigned long arch_cpu_id) "index: %d id: %lu" > kvm_irqchip_commit_routes(void) "" > kvm_irqchip_add_msi_route(char *name, int vector, int virq) "dev %s vector %d virq %d" > kvm_irqchip_update_msi_route(int virq) "Updating MSI route virq=%d" > @@ -25,7 +29,6 @@ kvm_dirty_ring_reaper(const char *s) "%s" > kvm_dirty_ring_reap(uint64_t count, int64_t t) "reaped %"PRIu64" pages (took %"PRIi64" us)" > kvm_dirty_ring_reaper_kick(const char *reason) "%s" > kvm_dirty_ring_flush(int finished) "%d" > -kvm_destroy_vcpu(void) "" > kvm_failed_get_vcpu_mmap_size(void) "" > kvm_cpu_exec(void) "" > kvm_interrupt_exit_request(void) "" > diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h > index fad9a7e8ff..2ed928aa71 100644 > --- a/include/sysemu/kvm.h > +++ b/include/sysemu/kvm.h > @@ -435,6 +435,22 @@ void kvm_set_sigmask_len(KVMState *s, unsigned int sigmask_len); > int kvm_physical_memory_addr_from_host(KVMState *s, void *ram_addr, > hwaddr *phys_addr); > > +/** > + * kvm_create_vcpu - Gets a parked KVM vCPU or creates a KVM vCPU > + * @cpu: QOM CPUState object for which KVM vCPU has to be fetched/created. > + * > + * @returns: 0 when success, errno (<0) when failed. > + */ > +int kvm_create_vcpu(CPUState *cpu); > + > +/** > + * kvm_park_vcpu - Park QEMU KVM vCPU context > + * @cpu: QOM CPUState object for which QEMU KVM vCPU context has to be parked. > + * > + * @returns: none > + */ > +void kvm_park_vcpu(CPUState *cpu); > + > #endif /* NEED_CPU_H */ > > void kvm_cpu_synchronize_state(CPUState *cpu);