Re: [PATCH 2/4] s390x: Cleanup cpu resets

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Hi Janosh,

On 11/22/19 8:52 AM, Janosch Frank wrote:
> Let's move the resets into one function and switch by type, so we can
> use fallthroughs for shared reset actions.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>   target/s390x/cpu.c | 110 ++++++++++++++++++++-------------------------
>   1 file changed, 48 insertions(+), 62 deletions(-)
> 
> diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c
> index 3abe7e80fd..556afecbc1 100644
> --- a/target/s390x/cpu.c
> +++ b/target/s390x/cpu.c
> @@ -82,67 +82,52 @@ static void s390_cpu_load_normal(CPUState *s)
>   }
>   #endif
>   
> -/* S390CPUClass::cpu_reset() */
> -static void s390_cpu_reset(CPUState *s)
> +typedef enum cpu_reset_type {
> +    S390_CPU_RESET_NORMAL,
> +    S390_CPU_RESET_INITIAL,
> +    S390_CPU_RESET_CLEAR,
> +} cpu_reset_type;
> +
> +static void s390_cpu_reset(CPUState *s, cpu_reset_type type)
>   {
>       S390CPU *cpu = S390_CPU(s);
>       S390CPUClass *scc = S390_CPU_GET_CLASS(cpu);
>       CPUS390XState *env = &cpu->env;
>   
> -    env->pfault_token = -1UL;
> -    env->bpbc = false;
>       scc->parent_reset(s);
>       cpu->env.sigp_order = 0;
>       s390_cpu_set_state(S390_CPU_STATE_STOPPED, cpu);
> -}
>   
> -/* S390CPUClass::initial_reset() */
> -static void s390_cpu_initial_reset(CPUState *s)
> -{
> -    S390CPU *cpu = S390_CPU(s);
> -    CPUS390XState *env = &cpu->env;
> +    /* Set initial values after clearing */
> +    switch (type) {
> +    case S390_CPU_RESET_CLEAR:
> +        memset(env, 0, offsetof(CPUS390XState, start_initial_reset_fields));
> +        /* Fallthrough */
> +    case S390_CPU_RESET_INITIAL:
> +        memset(&env->start_initial_reset_fields, 0,
> +               offsetof(CPUS390XState, end_reset_fields) -
> +               offsetof(CPUS390XState, start_initial_reset_fields));
> +        /* architectured initial values for CR 0 and 14 */
> +        env->cregs[0] = CR0_RESET;
> +        env->cregs[14] = CR14_RESET;
>   
> -    s390_cpu_reset(s);
> -    /* initial reset does not clear everything! */
> -    memset(&env->start_initial_reset_fields, 0,
> -        offsetof(CPUS390XState, end_reset_fields) -
> -        offsetof(CPUS390XState, start_initial_reset_fields));
> -
> -    /* architectured initial values for CR 0 and 14 */
> -    env->cregs[0] = CR0_RESET;
> -    env->cregs[14] = CR14_RESET;
> -
> -    /* architectured initial value for Breaking-Event-Address register */
> -    env->gbea = 1;
> -
> -    env->pfault_token = -1UL;
> -
> -    /* tininess for underflow is detected before rounding */
> -    set_float_detect_tininess(float_tininess_before_rounding,
> -                              &env->fpu_status);
> +        /* architectured initial value for Breaking-Event-Address register */
> +        env->gbea = 1;
> +        /* tininess for underflow is detected before rounding */
> +        set_float_detect_tininess(float_tininess_before_rounding,
> +                                  &env->fpu_status);
> +        /* Fallthrough */
> +    case S390_CPU_RESET_NORMAL:
> +        env->pfault_token = -1UL;
> +        env->bpbc = false;
> +        break;
> +    }
>   
>       /* Reset state inside the kernel that we cannot access yet from QEMU. */
> -    if (kvm_enabled()) {
> -        kvm_s390_reset_vcpu(cpu);
> +    if (kvm_enabled() && (type == S390_CPU_RESET_CLEAR ||
> +                          type == S390_CPU_RESET_INITIAL)) {
> +            kvm_s390_reset_vcpu(cpu);
>       }
> -}
> -
> -/* CPUClass:reset() */
> -static void s390_cpu_full_reset(CPUState *s)
> -{
> -    S390CPU *cpu = S390_CPU(s);
> -    S390CPUClass *scc = S390_CPU_GET_CLASS(cpu);
> -    CPUS390XState *env = &cpu->env;
> -
> -    scc->parent_reset(s);
> -    cpu->env.sigp_order = 0;
> -    s390_cpu_set_state(S390_CPU_STATE_STOPPED, cpu);
> -
> -    memset(env, 0, offsetof(CPUS390XState, end_reset_fields));
> -
> -    /* architectured initial values for CR 0 and 14 */
> -    env->cregs[0] = CR0_RESET;
> -    env->cregs[14] = CR14_RESET;
>   
>   #if defined(CONFIG_USER_ONLY)
>       /* user mode should always be allowed to use the full FPU */
> @@ -151,20 +136,21 @@ static void s390_cpu_full_reset(CPUState *s)
>           env->cregs[0] |= CR0_VECTOR;
>       }
>   #endif
> +}
>   
> -    /* architectured initial value for Breaking-Event-Address register */
> -    env->gbea = 1;
> +static void s390_cpu_reset_normal(CPUState *s)
> +{
> +    return s390_cpu_reset(s, S390_CPU_RESET_NORMAL);
> +}
>   
> -    env->pfault_token = -1UL;
> +static void s390_cpu_reset_initial(CPUState *s)
> +{
> +    return s390_cpu_reset(s, S390_CPU_RESET_INITIAL);
> +}
>   
> -    /* tininess for underflow is detected before rounding */
> -    set_float_detect_tininess(float_tininess_before_rounding,
> -                              &env->fpu_status);
> -
> -    /* Reset state inside the kernel that we cannot access yet from QEMU. */
> -    if (kvm_enabled()) {
> -        kvm_s390_reset_vcpu(cpu);
> -    }
> +static void s390_cpu_reset_clear(CPUState *s)
> +{
> +    return s390_cpu_reset(s, S390_CPU_RESET_CLEAR);
>   }
>   
>   #if !defined(CONFIG_USER_ONLY)
> @@ -473,9 +459,9 @@ static void s390_cpu_class_init(ObjectClass *oc, void *data)
>   #if !defined(CONFIG_USER_ONLY)
>       scc->load_normal = s390_cpu_load_normal;
>   #endif
> -    scc->cpu_reset = s390_cpu_reset;
> -    scc->initial_cpu_reset = s390_cpu_initial_reset;
> -    cc->reset = s390_cpu_full_reset;
> +    scc->cpu_reset = s390_cpu_reset_normal;
> +    scc->initial_cpu_reset = s390_cpu_reset_initial;
> +    cc->reset = s390_cpu_reset_clear;
>       cc->class_by_name = s390_cpu_class_by_name,
>       cc->has_work = s390_cpu_has_work;
>   #ifdef CONFIG_TCG
> 

This is a nice cleanup, but the patch is hard to digest.
Maybe you can split it in 3, one patch for each cpu_reset_type.

Regards,

Phil.