Re: [PATCH v2 1/1] hw/ppc: free env->tb_env in spapr_unrealize_vcpu()

[David Gibson]

On Tue, Mar 29, 2022 at 09:45:45AM -0300, Daniel Henrique Barboza wrote:
> The timebase is allocated during spapr_realize_vcpu() and it's not
> freed. This results in memory leaks when doing vcpu unplugs:
> 
> ==636935==
> ==636935== 144 (96 direct, 48 indirect) bytes in 1 blocks are definitely lost 
> in loss record 6
> ,461 of 8,135
> ==636935==    at 0x4897468: calloc (vg_replace_malloc.c:760)
> ==636935==    by 0x5077213: g_malloc0 (in /usr/lib64/libglib-2.0.so.0.6400.4)
> ==636935==    by 0x507757F: g_malloc0_n (in 
> /usr/lib64/libglib-2.0.so.0.6400.4)
> ==636935==    by 0x93C3FB: cpu_ppc_tb_init (ppc.c:1066)
> ==636935==    by 0x97BC2B: spapr_realize_vcpu (spapr_cpu_core.c:268)
> ==636935==    by 0x97C01F: spapr_cpu_core_realize (spapr_cpu_core.c:337)
> ==636935==    by 0xD4626F: device_set_realized (qdev.c:531)
> ==636935==    by 0xD55273: property_set_bool (object.c:2273)
> ==636935==    by 0xD523DF: object_property_set (object.c:1408)
> ==636935==    by 0xD588B7: object_property_set_qobject (qom-qobject.c:28)
> ==636935==    by 0xD52897: object_property_set_bool (object.c:1477)
> ==636935==    by 0xD4579B: qdev_realize (qdev.c:333)
> ==636935==
> 
> This patch adds a cpu_ppc_tb_free() helper in hw/ppc/ppc.c to allow us
> to free the timebase. This leak is then solved by calling
> cpu_ppc_tb_free() in spapr_unrealize_vcpu().
> 
> Fixes: 6f4b5c3ec590 ("spapr: CPU hot unplug support")
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  hw/ppc/ppc.c            | 7 +++++++
>  hw/ppc/spapr_cpu_core.c | 3 +++
>  include/hw/ppc/ppc.h    | 1 +
>  3 files changed, 11 insertions(+)
> 
> diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
> index faa02d6710..fea70df45e 100644
> --- a/hw/ppc/ppc.c
> +++ b/hw/ppc/ppc.c
> @@ -1083,6 +1083,13 @@ clk_setup_cb cpu_ppc_tb_init (CPUPPCState *env, 
> uint32_t freq)
>      return &cpu_ppc_set_tb_clk;
>  }
>  
> +void cpu_ppc_tb_free(CPUPPCState *env)
> +{
> +    timer_free(env->tb_env->decr_timer);
> +    timer_free(env->tb_env->hdecr_timer);
> +    g_free(env->tb_env);
> +}
> +
>  /* cpu_ppc_hdecr_init may be used if the timer is not used by HDEC emulation 
> */
>  void cpu_ppc_hdecr_init(CPUPPCState *env)
>  {
> diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> index ed84713960..8a4861f45a 100644
> --- a/hw/ppc/spapr_cpu_core.c
> +++ b/hw/ppc/spapr_cpu_core.c
> @@ -189,10 +189,13 @@ static const VMStateDescription vmstate_spapr_cpu_state 
> = {
>  
>  static void spapr_unrealize_vcpu(PowerPCCPU *cpu, SpaprCpuCore *sc)
>  {
> +    CPUPPCState *env = &cpu->env;
> +
>      if (!sc->pre_3_0_migration) {
>          vmstate_unregister(NULL, &vmstate_spapr_cpu_state, 
> cpu->machine_data);
>      }
>      spapr_irq_cpu_intc_destroy(SPAPR_MACHINE(qdev_get_machine()), cpu);
> +    cpu_ppc_tb_free(env);
>      qdev_unrealize(DEVICE(cpu));
>  }
>  
> diff --git a/include/hw/ppc/ppc.h b/include/hw/ppc/ppc.h
> index b0ba4bd6b9..364f165b4b 100644
> --- a/include/hw/ppc/ppc.h
> +++ b/include/hw/ppc/ppc.h
> @@ -54,6 +54,7 @@ struct ppc_tb_t {
>  
>  uint64_t cpu_ppc_get_tb(ppc_tb_t *tb_env, uint64_t vmclk, int64_t tb_offset);
>  clk_setup_cb cpu_ppc_tb_init (CPUPPCState *env, uint32_t freq);
> +void cpu_ppc_tb_free(CPUPPCState *env);
>  void cpu_ppc_hdecr_init(CPUPPCState *env);
>  void cpu_ppc_hdecr_exit(CPUPPCState *env);
>  

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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