Re: [PATCH RFC V6 10/24] arm/virt: Init PMU at host for all present vCPUs

[Igor Mammedov <imammedo@redhat.com>]

On Wed,  1 Oct 2025 01:01:13 +0000
salil.mehta@opnsrc.net wrote:

> From: Salil Mehta <salil.mehta@huawei.com>
> 

...

> diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
> index 5eaf41a566..2ee202a8a5 100644
> --- a/include/hw/core/cpu.h
> +++ b/include/hw/core/cpu.h
> @@ -602,6 +602,63 @@ extern CPUTailQ cpus_queue;
>  #define CPU_FOREACH_SAFE(cpu, next_cpu) \
>      QTAILQ_FOREACH_SAFE_RCU(cpu, &cpus_queue, node, next_cpu)
>  
> +
> +/**
> + * CPU_FOREACH_POSSIBLE(cpu_, archid_list_)
> + *
> + * Iterate over all entries in a CPUArchIdList, assigning each entry’s
> + * CPUState* to @cpu_. This hides the loop index and reads like a normal
> + * C for-loop.
> + *
> + * A CPUArchIdList represents the set of *possible* CPUs for a machine.
> + * Each entry contains:
> + *   - @cpu:        CPUState pointer, or NULL if not realized yet
> + *   - @arch_id:    architecture-specific identifier (e.g. MPIDR)
> + *   - @vcpus_count: number of vCPUs represented (usually 1)
> + *
> + * The list models *possible* CPUs: it includes (a) currently plugged vCPUs
> + * made available through hotplug, (b) present (and perhaps visible to OSPM)
> + * but kept ACPI-disabled vCPUs, and (c) reserved slots for CPUs that may be
> + * created in the future. This supports co-existence of hotpluggable and
> + * admin-disabled vCPUs if architectures permit.
> + *
> + * Example:
> + *
> + *   CPUArchIdList *alist = machine_possible_cpus(ms);
> + *   CPUState *cpu;
> + *
> + *   CPU_FOREACH_POSSIBLE(cpu, alist) {
> + *       if (!cpu) {
> + *           continue; // reserved slot for hotplug case
> + *       }
> + *
> + *       < Do Something >
> + *   }
> + *
> + * Expanded equivalent:
> + *
> + *   for (int __cpu_idx = 0; alist && __cpu_idx < alist->len; __cpu_idx++) {
> + *       if ((cpu = alist->cpus[__cpu_idx].cpu, 1)) {
> + *           if (!cpu) {
> + *               continue;
> + *           }
> + *
> + *           < Do Something >
> + *       }
> + *   }
> + *
> + * Notes:
> + *   - Callers must check @cpu for NULL when filtering unplugged CPUs.
> + *   - Mirrors the style of CPU_FOREACH(), but iterates all *possible* CPUs
> + *     (plugged, ACPI-disabled, and reserved slots) rather than only present
> + *     and enabled vCPUs.
> + */
> +#define CPU_FOREACH_POSSIBLE(cpu_, archid_list_) \
> +    for (int __cpu_idx = 0; \
> +         (archid_list_) && __cpu_idx < (archid_list_)->len; \
> +         __cpu_idx++) \
> +        if (((cpu_) = (archid_list_)->cpus[__cpu_idx].cpu, 1))
> +
>  extern __thread CPUState *current_cpu;

make it a separate patch and refactor existing loops to use it.

>  
>  /**