Re: [PATCH v11 1/4] xen/device-tree: Parse 'cpu-map' node for CPU topology exploration

[Jan Beulich <jbeulich@xxxxxxxx>]

On 13.10.2026 12:36, Hirokazu Takahashi wrote:
> Parse the 'cpu-map' node in the Device Tree to extract CPU topology
> information. If the 'cpu-map' node is absent, simply ignore it.
> 
> Signed-off-by: Hirokazu Takahashi <taka@xxxxxxxxxxxxx>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> # common, acpi

Imo this should have been dropped, when the covered code ...

> ---
> Changes in v11:
>  - When parsing the Device Tree, ignore CPU nodes if the corresponding
>    physical CPU failed to boot, rather than treating it as an error.
>  - Drop the dependency on UNSUPPORTED for CPU topology support.
>  - Print an error message if memory allocation fails in init_cpu_topology().

... was touched at least for this change. Specifically ...

> --- /dev/null
> +++ b/xen/common/cpu-topology.c
> @@ -0,0 +1,69 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#include <xen/acpi.h>
> +#include <xen/cpu-topology.h>
> +#include <xen/cpumask.h>
> +#include <xen/dt-cpu-topology.h>
> +#include <xen/init.h>
> +#include <xen/xvmalloc.h>
> +
> +static void __init free_topology_table(void)
> +{
> +    unsigned int cpu;
> +
> +    for ( cpu = 0; cpu < nr_cpu_ids; cpu++ )
> +    {
> +        free_cpumask_var(cpu_topology[cpu].thread_sibling);
> +        free_cpumask_var(cpu_topology[cpu].core_sibling);
> +        free_cpumask_var(cpu_topology[cpu].cluster_sibling);
> +    }
> +
> +    XVFREE(cpu_topology);
> +}
> +
> +void __init init_cpu_topology(void)
> +{
> +    unsigned int cpu;
> +    int ret;
> +
> +    if ( num_possible_cpus() == 1 )
> +        return;
> +
> +    cpu_topology = xvzalloc_array(struct cpu_topology, nr_cpu_ids);
> +    if ( !cpu_topology )
> +    {
> +        printk(XENLOG_WARNING "CPU topology table allocation failed.\n");

... for one, nit: No full stops please in log messages. And then, how can
a reader of the log tell this message from ...

> +        return;
> +    }
> +
> +    for ( cpu = 0; cpu < nr_cpu_ids; cpu++ )
> +    {
> +        if ( !zalloc_cpumask_var(&cpu_topology[cpu].thread_sibling) ||
> +             !zalloc_cpumask_var(&cpu_topology[cpu].core_sibling) ||
> +             !zalloc_cpumask_var(&cpu_topology[cpu].cluster_sibling) )
> +        {
> +            free_topology_table();
> +            printk(XENLOG_WARNING "CPU topology table allocation failed.\n");

... this one? Or if the message is meant to be the same, perhaps you want
to fold both printk()s (likely by way of using goto)?

Jan