Re: [Qemu-devel] [PATCH RFC v5 3/7] qemu_init_vcpu: add a new Error parameter to propagate

[Fei Li <fli@suse.com>]

On 10/11/2018 09:19 PM, Markus Armbruster wrote:
> Fei Li <fli@suse.com> writes:
>
>> The caller of qemu_init_vcpu() already passed the **errp to handle
> Which caller?  There are many.  Or do you mean "The callers"?
Oh, sorry, I mean "The callers" :)
>
>> errors. In view of this, add a new Error parameter to the following
>> call trace to propagate the error and let the further caller check it.
> Which "call trace"?
Actually, I want to say all functions called by qemu_init_vcpu()..
>
>> Besides, make qemu_init_vcpu() return a Boolean value to let its
>> callers know whether it succeeds.
>>
>> Signed-off-by: Fei Li <fli@suse.com>
>> Reviewed-by: Fam Zheng <famz@redhat.com>
>> ---
>>   accel/tcg/user-exec-stub.c      |  2 +-
>>   cpus.c                          | 34 +++++++++++++++++++++-------------
>>   include/qom/cpu.h               |  2 +-
>>   target/alpha/cpu.c              |  4 +++-
>>   target/arm/cpu.c                |  4 +++-
>>   target/cris/cpu.c               |  4 +++-
>>   target/hppa/cpu.c               |  4 +++-
>>   target/i386/cpu.c               |  4 +++-
>>   target/lm32/cpu.c               |  4 +++-
>>   target/m68k/cpu.c               |  4 +++-
>>   target/microblaze/cpu.c         |  4 +++-
>>   target/mips/cpu.c               |  4 +++-
>>   target/moxie/cpu.c              |  4 +++-
>>   target/nios2/cpu.c              |  4 +++-
>>   target/openrisc/cpu.c           |  4 +++-
>>   target/ppc/translate_init.inc.c |  4 +++-
>>   target/riscv/cpu.c              |  4 +++-
>>   target/s390x/cpu.c              |  4 +++-
>>   target/sh4/cpu.c                |  4 +++-
>>   target/sparc/cpu.c              |  4 +++-
>>   target/tilegx/cpu.c             |  4 +++-
>>   target/tricore/cpu.c            |  4 +++-
>>   target/unicore32/cpu.c          |  4 +++-
>>   target/xtensa/cpu.c             |  4 +++-
>>   24 files changed, 86 insertions(+), 36 deletions(-)
>>
>> diff --git a/accel/tcg/user-exec-stub.c b/accel/tcg/user-exec-stub.c
>> index a32b4496af..38f6b928d4 100644
>> --- a/accel/tcg/user-exec-stub.c
>> +++ b/accel/tcg/user-exec-stub.c
>> @@ -10,7 +10,7 @@ void cpu_resume(CPUState *cpu)
>>   {
>>   }
>>   
>> -void qemu_init_vcpu(CPUState *cpu)
>> +bool qemu_init_vcpu(CPUState *cpu, Error **errp)
>>   {
> You need to return a value here.  Sure you compile-tested this?
Oops! I forget the TCG case.. The `return true` should be added.
Thanks for pointing this out!
>
>>   }
>>   
>> diff --git a/cpus.c b/cpus.c
>> index 361678e459..c4db70607e 100644
>> --- a/cpus.c
>> +++ b/cpus.c
>> @@ -1918,7 +1918,7 @@ void cpu_remove_sync(CPUState *cpu)
>>   /* For temporary buffers for forming a name */
>>   #define VCPU_THREAD_NAME_SIZE 16
>>   
>> -static void qemu_tcg_init_vcpu(CPUState *cpu)
>> +static void qemu_tcg_init_vcpu(CPUState *cpu, Error **errp)
>>   {
>>       char thread_name[VCPU_THREAD_NAME_SIZE];
>>       static QemuCond *single_tcg_halt_cond;
>> @@ -1974,7 +1974,7 @@ static void qemu_tcg_init_vcpu(CPUState *cpu)
>>       }
>>   }
>>   
>> -static void qemu_hax_start_vcpu(CPUState *cpu)
>> +static void qemu_hax_start_vcpu(CPUState *cpu, Error **errp)
>>   {
>>       char thread_name[VCPU_THREAD_NAME_SIZE];
>>   
>> @@ -1991,7 +1991,7 @@ static void qemu_hax_start_vcpu(CPUState *cpu)
>>   #endif
>>   }
>>   
>> -static void qemu_kvm_start_vcpu(CPUState *cpu)
>> +static void qemu_kvm_start_vcpu(CPUState *cpu, Error **errp)
>>   {
>>       char thread_name[VCPU_THREAD_NAME_SIZE];
>>   
>> @@ -2004,7 +2004,7 @@ static void qemu_kvm_start_vcpu(CPUState *cpu)
>>                          cpu, QEMU_THREAD_JOINABLE);
>>   }
>>   
>> -static void qemu_hvf_start_vcpu(CPUState *cpu)
>> +static void qemu_hvf_start_vcpu(CPUState *cpu, Error **errp)
>>   {
>>       char thread_name[VCPU_THREAD_NAME_SIZE];
>>   
>> @@ -2022,7 +2022,7 @@ static void qemu_hvf_start_vcpu(CPUState *cpu)
>>                          cpu, QEMU_THREAD_JOINABLE);
>>   }
>>   
>> -static void qemu_whpx_start_vcpu(CPUState *cpu)
>> +static void qemu_whpx_start_vcpu(CPUState *cpu, Error **errp)
>>   {
>>       char thread_name[VCPU_THREAD_NAME_SIZE];
>>   
>> @@ -2038,7 +2038,7 @@ static void qemu_whpx_start_vcpu(CPUState *cpu)
>>   #endif
>>   }
>>   
>> -static void qemu_dummy_start_vcpu(CPUState *cpu)
>> +static void qemu_dummy_start_vcpu(CPUState *cpu, Error **errp)
>>   {
>>       char thread_name[VCPU_THREAD_NAME_SIZE];
>>   
>> @@ -2051,11 +2051,12 @@ static void qemu_dummy_start_vcpu(CPUState *cpu)
>>                          QEMU_THREAD_JOINABLE);
>>   }
>>   
>> -void qemu_init_vcpu(CPUState *cpu)
>> +bool qemu_init_vcpu(CPUState *cpu, Error **errp)
>>   {
>>       cpu->nr_cores = smp_cores;
>>       cpu->nr_threads = smp_threads;
>>       cpu->stopped = true;
>> +    Error *local_err = NULL;
>>   
>>       if (!cpu->as) {
>>           /* If the target cpu hasn't set up any address spaces itself,
>> @@ -2066,22 +2067,29 @@ void qemu_init_vcpu(CPUState *cpu)
>>       }
>>   
>>       if (kvm_enabled()) {
>> -        qemu_kvm_start_vcpu(cpu);
>> +        qemu_kvm_start_vcpu(cpu, &local_err);
>>       } else if (hax_enabled()) {
>> -        qemu_hax_start_vcpu(cpu);
>> +        qemu_hax_start_vcpu(cpu, &local_err);
>>       } else if (hvf_enabled()) {
>> -        qemu_hvf_start_vcpu(cpu);
>> +        qemu_hvf_start_vcpu(cpu, &local_err);
>>       } else if (tcg_enabled()) {
>> -        qemu_tcg_init_vcpu(cpu);
>> +        qemu_tcg_init_vcpu(cpu, &local_err);
>>       } else if (whpx_enabled()) {
>> -        qemu_whpx_start_vcpu(cpu);
>> +        qemu_whpx_start_vcpu(cpu, &local_err);
>>       } else {
>> -        qemu_dummy_start_vcpu(cpu);
>> +        qemu_dummy_start_vcpu(cpu, &local_err);
>> +    }
>> +
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>> +        return false;
>>       }
>>   
>>       while (!cpu->created) {
>>           qemu_cond_wait(&qemu_cpu_cond, &qemu_global_mutex);
>>       }
>> +
>> +    return true;
>>   }
>>   
>>   void cpu_stop_current(void)
>> diff --git a/include/qom/cpu.h b/include/qom/cpu.h
>> index dc130cd307..4d85dda175 100644
>> --- a/include/qom/cpu.h
>> +++ b/include/qom/cpu.h
>> @@ -1012,7 +1012,7 @@ void end_exclusive(void);
>>    *
>>    * Initializes a vCPU.
>>    */
>> -void qemu_init_vcpu(CPUState *cpu);
>> +bool qemu_init_vcpu(CPUState *cpu, Error **errp);
>>   
>>   #define SSTEP_ENABLE  0x1  /* Enable simulated HW single stepping */
>>   #define SSTEP_NOIRQ   0x2  /* Do not use IRQ while single stepping */
>> diff --git a/target/alpha/cpu.c b/target/alpha/cpu.c
>> index b08078e7fc..d531bd4f7e 100644
>> --- a/target/alpha/cpu.c
>> +++ b/target/alpha/cpu.c
>> @@ -66,7 +66,9 @@ static void alpha_cpu_realizefn(DeviceState *dev, Error **errp)
>>           return;
>>       }
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       acc->parent_realize(dev, errp);
>>   }
>> diff --git a/target/arm/cpu.c b/target/arm/cpu.c
>> index b5e61cc177..40f300174d 100644
>> --- a/target/arm/cpu.c
>> +++ b/target/arm/cpu.c
>> @@ -1038,7 +1038,9 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
>>       }
>>   #endif
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>       cpu_reset(cs);
>>   
>>       acc->parent_realize(dev, errp);
>> diff --git a/target/cris/cpu.c b/target/cris/cpu.c
>> index a23aba2688..ec92d69781 100644
>> --- a/target/cris/cpu.c
>> +++ b/target/cris/cpu.c
>> @@ -140,7 +140,9 @@ static void cris_cpu_realizefn(DeviceState *dev, Error **errp)
>>       }
>>   
>>       cpu_reset(cs);
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       ccc->parent_realize(dev, errp);
>>   }
>> diff --git a/target/hppa/cpu.c b/target/hppa/cpu.c
>> index 00bf444620..08f600ced9 100644
>> --- a/target/hppa/cpu.c
>> +++ b/target/hppa/cpu.c
>> @@ -98,7 +98,9 @@ static void hppa_cpu_realizefn(DeviceState *dev, Error **errp)
>>           return;
>>       }
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>       acc->parent_realize(dev, errp);
>>   
>>   #ifndef CONFIG_USER_ONLY
>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>> index c88876dfe3..d199f91258 100644
>> --- a/target/i386/cpu.c
>> +++ b/target/i386/cpu.c
>> @@ -5112,7 +5112,9 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp)
>>       }
>>   #endif
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       /*
>>        * Most Intel and certain AMD CPUs support hyperthreading. Even though QEMU
>> diff --git a/target/lm32/cpu.c b/target/lm32/cpu.c
>> index b7499cb627..d50b1e4a43 100644
>> --- a/target/lm32/cpu.c
>> +++ b/target/lm32/cpu.c
>> @@ -139,7 +139,9 @@ static void lm32_cpu_realizefn(DeviceState *dev, Error **errp)
>>   
>>       cpu_reset(cs);
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       lcc->parent_realize(dev, errp);
>>   }
>> diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c
>> index 582e3a73b3..4ab53f2d58 100644
>> --- a/target/m68k/cpu.c
>> +++ b/target/m68k/cpu.c
>> @@ -231,7 +231,9 @@ static void m68k_cpu_realizefn(DeviceState *dev, Error **errp)
>>       m68k_cpu_init_gdb(cpu);
>>   
>>       cpu_reset(cs);
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       mcc->parent_realize(dev, errp);
>>   }
>> diff --git a/target/microblaze/cpu.c b/target/microblaze/cpu.c
>> index 9b546a2c18..3906c864a3 100644
>> --- a/target/microblaze/cpu.c
>> +++ b/target/microblaze/cpu.c
>> @@ -161,7 +161,9 @@ static void mb_cpu_realizefn(DeviceState *dev, Error **errp)
>>           return;
>>       }
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       env->pvr.regs[0] = PVR0_USE_EXC_MASK \
>>                          | PVR0_USE_ICACHE_MASK \
>> diff --git a/target/mips/cpu.c b/target/mips/cpu.c
>> index 497706b669..62be84af76 100644
>> --- a/target/mips/cpu.c
>> +++ b/target/mips/cpu.c
>> @@ -136,7 +136,9 @@ static void mips_cpu_realizefn(DeviceState *dev, Error **errp)
>>       cpu_mips_realize_env(&cpu->env);
>>   
>>       cpu_reset(cs);
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       mcc->parent_realize(dev, errp);
>>   }
>> diff --git a/target/moxie/cpu.c b/target/moxie/cpu.c
>> index 8d67eb6727..8581a6d922 100644
>> --- a/target/moxie/cpu.c
>> +++ b/target/moxie/cpu.c
>> @@ -66,7 +66,9 @@ static void moxie_cpu_realizefn(DeviceState *dev, Error **errp)
>>           return;
>>       }
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>       cpu_reset(cs);
>>   
>>       mcc->parent_realize(dev, errp);
>> diff --git a/target/nios2/cpu.c b/target/nios2/cpu.c
>> index fbfaa2ce26..5c7b4b486e 100644
>> --- a/target/nios2/cpu.c
>> +++ b/target/nios2/cpu.c
>> @@ -94,7 +94,9 @@ static void nios2_cpu_realizefn(DeviceState *dev, Error **errp)
>>           return;
>>       }
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>       cpu_reset(cs);
>>   
>>       ncc->parent_realize(dev, errp);
>> diff --git a/target/openrisc/cpu.c b/target/openrisc/cpu.c
>> index fb7cb5c507..a6dcdb9df9 100644
>> --- a/target/openrisc/cpu.c
>> +++ b/target/openrisc/cpu.c
>> @@ -83,7 +83,9 @@ static void openrisc_cpu_realizefn(DeviceState *dev, Error **errp)
>>           return;
>>       }
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>       cpu_reset(cs);
>>   
>>       occ->parent_realize(dev, errp);
>> diff --git a/target/ppc/translate_init.inc.c b/target/ppc/translate_init.inc.c
>> index 263e63cb03..a6dd2318a6 100644
>> --- a/target/ppc/translate_init.inc.c
>> +++ b/target/ppc/translate_init.inc.c
>> @@ -9694,7 +9694,9 @@ static void ppc_cpu_realize(DeviceState *dev, Error **errp)
>>                                    32, "power-vsx.xml", 0);
>>       }
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        goto unrealize;
>> +    }
>>   
>>       pcc->parent_realize(dev, errp);
>>   
>> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
>> index d630e8fd6c..ef56215e92 100644
>> --- a/target/riscv/cpu.c
>> +++ b/target/riscv/cpu.c
>> @@ -303,7 +303,9 @@ static void riscv_cpu_realize(DeviceState *dev, Error **errp)
>>           return;
>>       }
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>       cpu_reset(cs);
>>   
>>       mcc->parent_realize(dev, errp);
>> diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c
>> index 18ba7f85a5..2a3eac9761 100644
>> --- a/target/s390x/cpu.c
>> +++ b/target/s390x/cpu.c
>> @@ -222,7 +222,9 @@ static void s390_cpu_realizefn(DeviceState *dev, Error **errp)
>>       qemu_register_reset(s390_cpu_machine_reset_cb, cpu);
>>   #endif
>>       s390_cpu_gdb_init(cs);
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       /*
>>        * KVM requires the initial CPU reset ioctl to be executed on the target
>> diff --git a/target/sh4/cpu.c b/target/sh4/cpu.c
>> index b9f393b7c7..d32ef2e1cb 100644
>> --- a/target/sh4/cpu.c
>> +++ b/target/sh4/cpu.c
>> @@ -196,7 +196,9 @@ static void superh_cpu_realizefn(DeviceState *dev, Error **errp)
>>       }
>>   
>>       cpu_reset(cs);
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       scc->parent_realize(dev, errp);
>>   }
>> diff --git a/target/sparc/cpu.c b/target/sparc/cpu.c
>> index 0f090ece54..9c22f6a7df 100644
>> --- a/target/sparc/cpu.c
>> +++ b/target/sparc/cpu.c
>> @@ -773,7 +773,9 @@ static void sparc_cpu_realizefn(DeviceState *dev, Error **errp)
>>           return;
>>       }
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       scc->parent_realize(dev, errp);
>>   }
>> diff --git a/target/tilegx/cpu.c b/target/tilegx/cpu.c
>> index bfe9be59b5..234148fabd 100644
>> --- a/target/tilegx/cpu.c
>> +++ b/target/tilegx/cpu.c
>> @@ -92,7 +92,9 @@ static void tilegx_cpu_realizefn(DeviceState *dev, Error **errp)
>>       }
>>   
>>       cpu_reset(cs);
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       tcc->parent_realize(dev, errp);
>>   }
>> diff --git a/target/tricore/cpu.c b/target/tricore/cpu.c
>> index 2edaef1aef..5482d6ea3f 100644
>> --- a/target/tricore/cpu.c
>> +++ b/target/tricore/cpu.c
>> @@ -96,7 +96,9 @@ static void tricore_cpu_realizefn(DeviceState *dev, Error **errp)
>>           set_feature(env, TRICORE_FEATURE_13);
>>       }
>>       cpu_reset(cs);
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       tcc->parent_realize(dev, errp);
>>   }
>> diff --git a/target/unicore32/cpu.c b/target/unicore32/cpu.c
>> index 68f978d80b..1f6a33b6f3 100644
>> --- a/target/unicore32/cpu.c
>> +++ b/target/unicore32/cpu.c
>> @@ -96,7 +96,9 @@ static void uc32_cpu_realizefn(DeviceState *dev, Error **errp)
>>           return;
>>       }
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       ucc->parent_realize(dev, errp);
>>   }
>> diff --git a/target/xtensa/cpu.c b/target/xtensa/cpu.c
>> index a54dbe4260..d2351c9b20 100644
>> --- a/target/xtensa/cpu.c
>> +++ b/target/xtensa/cpu.c
>> @@ -131,7 +131,9 @@ static void xtensa_cpu_realizefn(DeviceState *dev, Error **errp)
>>   
>>       cs->gdb_num_regs = xcc->config->gdb_regmap.num_regs;
>>   
>> -    qemu_init_vcpu(cs);
>> +    if (!qemu_init_vcpu(cs, errp)) {
>> +        return;
>> +    }
>>   
>>       xcc->parent_realize(dev, errp);
>>   }
> I see how you changed the code to pass an Error from the
> qemu_FOO_start_vcpu() through qemu_init_vcpu() to its callers.  I can't
> see how such errors can be created.  Without a way to create any, the
> patch is pointless.  What am I missing?
This patch is also the pre-patch for the updated qemu_thread_create() in 
patch 7/7
just as I explained in patch 2/7 [Issue1].

Have a nice day, thanks
Fei