Re: [PATCH] cpu: Initialize nr_cores and nr_threads in cpu_common_initfn()

[Philippe Mathieu-Daudé]

On 22/11/24 17:03, Xiaoyao Li wrote:
> Currently cpu->nr_cores and cpu->nr_threads are initialized in
> qemu_init_vcpu(), which is called a bit late in *cpu_realizefn() for
> each ARCHes.
>
> x86 arch would like to use nr_cores and nr_threads earlier in its
> realizefn(). To serve this purpose, initialize nr_cores and nr_threads
> in cpu_common_initfn(), which is earlier than *cpu_realizefn().
>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> ---
>   hw/core/cpu-common.c | 10 +++++++++-
>   system/cpus.c        |  4 ----
>   2 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/hw/core/cpu-common.c b/hw/core/cpu-common.c
> index 09c79035949b..6de92ed854bc 100644
> --- a/hw/core/cpu-common.c
> +++ b/hw/core/cpu-common.c
> @@ -237,14 +237,22 @@ static void cpu_common_unrealizefn(DeviceState *dev)
>   static void cpu_common_initfn(Object *obj)
>   {
>       CPUState *cpu = CPU(obj);
> +    Object *machine = qdev_get_machine();
> +    MachineState *ms;
>   
>       gdb_init_cpu(cpu);
>       cpu->cpu_index = UNASSIGNED_CPU_INDEX;
>       cpu->cluster_index = UNASSIGNED_CLUSTER_INDEX;
>       /* user-mode doesn't have configurable SMP topology */
> -    /* the default value is changed by qemu_init_vcpu() for system-mode */
>       cpu->nr_cores = 1;
>       cpu->nr_threads = 1;
> +#ifndef CONFIG_USER_ONLY

Is CONFIG_USER_ONLY available in an common_ss[] object? I don't recall.

Anyway, can we not use CONFIG_USER_ONLY in cpu-common.c?

> +    if (object_dynamic_cast(machine, TYPE_MACHINE)) {
> +        ms = MACHINE(machine);
> +        cpu->nr_cores = machine_topo_get_cores_per_socket(ms);
> +        cpu->nr_threads = ms->smp.threads;
> +    }
> +#endif
>       cpu->cflags_next_tb = -1;
>   
>       /* allocate storage for thread info, initialise condition variables */
> diff --git a/system/cpus.c b/system/cpus.c
> index 1c818ff6828c..c1547fbfd39b 100644
> --- a/system/cpus.c
> +++ b/system/cpus.c
> @@ -664,10 +664,6 @@ const AccelOpsClass *cpus_get_accel(void)
>   
>   void qemu_init_vcpu(CPUState *cpu)
>   {
> -    MachineState *ms = MACHINE(qdev_get_machine());
> -
> -    cpu->nr_cores = machine_topo_get_cores_per_socket(ms);
> -    cpu->nr_threads =  ms->smp.threads;
>       cpu->stopped = true;
>       cpu->random_seed = qemu_guest_random_seed_thread_part1();
>