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Re: [Qemu-devel] [PATCH v3 7/7] cpus: reclaim allocated vCPU objects


From: Bharata B Rao
Subject: Re: [Qemu-devel] [PATCH v3 7/7] cpus: reclaim allocated vCPU objects
Date: Wed, 4 Mar 2015 14:10:44 +0530

On Fri, Feb 13, 2015 at 4:10 PM, Zhu Guihua <address@hidden> wrote:
> From: Gu Zheng <address@hidden>
>
> After ACPI get a signal to eject a vCPU, the vCPU must be
> removed from CPU list´╝îbefore the vCPU really removed,  then
> release the all related vCPU objects.
>
> In order to deal well with the kvm vcpus (which can not be removed without any
> protection), we do not close KVM vcpu fd, just record and mark it as stopped
> into a list, so that we can reuse it for the appending cpu hot-add request if
> possible. It is also the approach that kvm guys suggested:
> https://www.mail-archive.com/address@hidden/msg102839.html
>
> Signed-off-by: Chen Fan <address@hidden>
> Signed-off-by: Gu Zheng <address@hidden>
> Signed-off-by: Zhu Guihua <address@hidden>
> ---
>  cpus.c               | 37 ++++++++++++++++++++++++++++++++++
>  include/sysemu/kvm.h |  1 +
>  kvm-all.c            | 57 
> +++++++++++++++++++++++++++++++++++++++++++++++++++-
>  3 files changed, 94 insertions(+), 1 deletion(-)
>
> diff --git a/cpus.c b/cpus.c
> index d6e5a5f..a11941f 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -854,6 +854,24 @@ void async_run_on_cpu(CPUState *cpu, void (*func)(void 
> *data), void *data)
>      qemu_cpu_kick(cpu);
>  }
>
> +static void qemu_kvm_destroy_vcpu(CPUState *cpu)
> +{
> +    CPU_REMOVE(cpu);
> +
> +    if (kvm_destroy_vcpu(cpu) < 0) {
> +        error_report("kvm_destroy_vcpu failed.\n");
> +        exit(EXIT_FAILURE);
> +    }
> +
> +    object_unparent(OBJECT(cpu));
> +}
> +
> +static void qemu_tcg_destroy_vcpu(CPUState *cpu)
> +{
> +    CPU_REMOVE(cpu);
> +    object_unparent(OBJECT(cpu));
> +}
> +
>  static void flush_queued_work(CPUState *cpu)
>  {
>      struct qemu_work_item *wi;
> @@ -946,6 +964,11 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
>              }
>          }
>          qemu_kvm_wait_io_event(cpu);
> +        if (cpu->exit && !cpu_can_run(cpu)) {
> +            qemu_kvm_destroy_vcpu(cpu);
> +            qemu_mutex_unlock(&qemu_global_mutex);
> +            return NULL;
> +        }
>      }
>
>      return NULL;
> @@ -999,6 +1022,7 @@ static void tcg_exec_all(void);
>  static void *qemu_tcg_cpu_thread_fn(void *arg)
>  {
>      CPUState *cpu = arg;
> +    CPUState *remove_cpu = NULL;
>
>      qemu_tcg_init_cpu_signals();
>      qemu_thread_get_self(cpu->thread);
> @@ -1032,6 +1056,16 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
>              }
>          }
>          qemu_tcg_wait_io_event();
> +        CPU_FOREACH(cpu) {
> +            if (cpu->exit && !cpu_can_run(cpu)) {
> +                remove_cpu = cpu;
> +                break;
> +            }
> +        }
> +        if (remove_cpu) {
> +            qemu_tcg_destroy_vcpu(remove_cpu);
> +            remove_cpu = NULL;
> +        }
>      }
>
>      return NULL;
> @@ -1389,6 +1423,9 @@ static void tcg_exec_all(void)
>                  break;
>              }
>          } else if (cpu->stop || cpu->stopped) {
> +            if (cpu->exit) {
> +                next_cpu = CPU_NEXT(cpu);
> +            }
>              break;
>          }
>      }
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index 30cb84d..560caef 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -188,6 +188,7 @@ int kvm_has_intx_set_mask(void);
>
>  int kvm_init_vcpu(CPUState *cpu);
>  int kvm_cpu_exec(CPUState *cpu);
> +int kvm_destroy_vcpu(CPUState *cpu);
>
>  #ifdef NEED_CPU_H
>
> diff --git a/kvm-all.c b/kvm-all.c
> index 05a79c2..46e7853 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -71,6 +71,12 @@ typedef struct KVMSlot
>
>  typedef struct kvm_dirty_log KVMDirtyLog;
>
> +struct KVMParkedVcpu {
> +    unsigned long vcpu_id;
> +    int kvm_fd;
> +    QLIST_ENTRY(KVMParkedVcpu) node;
> +};
> +
>  struct KVMState
>  {
>      AccelState parent_obj;
> @@ -107,6 +113,7 @@ struct KVMState
>      QTAILQ_HEAD(msi_hashtab, KVMMSIRoute) msi_hashtab[KVM_MSI_HASHTAB_SIZE];
>      bool direct_msi;
>  #endif
> +    QLIST_HEAD(, KVMParkedVcpu) kvm_parked_vcpus;
>  };
>
>  #define TYPE_KVM_ACCEL ACCEL_CLASS_NAME("kvm")
> @@ -247,6 +254,53 @@ static int kvm_set_user_memory_region(KVMState *s, 
> KVMSlot *slot)
>      return kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem);
>  }
>
> +int kvm_destroy_vcpu(CPUState *cpu)

You need to provide a stub for this in kvm-stub.c without which I see
that aarch64-softmmu won't compile.

Regards,
Bharata.



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