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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id k13-20020a17090666cd00b009b65a834dd6sm1168699ejp.215.2023.10.27.05.56.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Oct 2023 05:56:55 -0700 (PDT) Date: Fri, 27 Oct 2023 14:56:52 +0200 From: Igor Mammedov To: Salil Mehta Cc: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH V6 1/9] accel/kvm: Extract common KVM vCPU {creation,parking} code Message-ID: <20231027145652.44cc845c@imammedo.users.ipa.redhat.com> In-Reply-To: <20231013105129.25648-2-salil.mehta@huawei.com> References: <20231013105129.25648-1-salil.mehta@huawei.com> <20231013105129.25648-2-salil.mehta@huawei.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TUID: beNInolYdLW9 On Fri, 13 Oct 2023 11:51:21 +0100 Salil Mehta wrote: > KVM vCPU creation is done once during the initialization of the VM when Qemu ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > thread is spawned. This is common to all the architectures. is it really true fox x86? > > 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 and its ^ since KVM doesn't support vCPU removal > representative KVM vCPU object/context in Qemu is parked. > > Refactor common logic so that some APIs could be reused by vCPU Hotplug code. 'reused' part doesn't happen within this series. So a reason why patch exists is not clear/no one can deduce the reason without the actual user here. Suggest to move it to a series that actually will use this patch. > Update new/old APIs with trace events instead of DTRACE. > > Signed-off-by: Salil Mehta > Reviewed-by: Gavin Shan > Tested-by: Vishnu Pajjuri > Reviewed-by: Jonathan Cameron > Tested-by: Xianglai Li > --- > accel/kvm/kvm-all.c | 64 ++++++++++++++++++++++++++++++++---------- > accel/kvm/trace-events | 4 +++ > include/sysemu/kvm.h | 16 +++++++++++ > 3 files changed, 69 insertions(+), 15 deletions(-) > > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c > index 72e1d1141c..bfa7816aaa 100644 > --- a/accel/kvm/kvm-all.c > +++ b/accel/kvm/kvm-all.c > @@ -137,6 +137,7 @@ 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) > { > @@ -320,14 +321,53 @@ 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; > > - DPRINTF("kvm_destroy_vcpu\n"); > + trace_kvm_destroy_vcpu(cpu->cpu_index, kvm_arch_vcpu_id(cpu)); > > ret = kvm_arch_destroy_vcpu(cpu); > if (ret < 0) { > @@ -353,10 +393,7 @@ 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; > } > @@ -377,6 +414,8 @@ 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); > @@ -384,7 +423,7 @@ 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) > @@ -395,19 +434,14 @@ 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)); > 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 399aaeb0ec..cdd0c95c09 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" > diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h > index ee9025f8e9..8137e6a44c 100644 > --- a/include/sysemu/kvm.h > +++ b/include/sysemu/kvm.h > @@ -465,6 +465,22 @@ 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);