Re: [PATCH 32/37] xen/arm: unified entry to parse all NUMA data from device tree

[Stefano Stabellini <sstabellini@kernel.org>]

On Thu, 23 Sep 2021, Wei Chen wrote:
> In this API, we scan whole device tree to parse CPU node id, memory
          ^ function   ^ the whole

> node id and distance-map. Though early_scan_node will invoke has a
> handler to process memory nodes. If we want to parse memory node id
> in this handler, we have to embeded NUMA parse code in this handler.
                              ^ embed

> But we still need to scan whole device tree to find CPU NUMA id and
> distance-map. In this case, we include memory NUMA id parse in this
> API too. Another benefit is that we have a unique entry for device
  ^ function

> tree NUMA data parse.

Ah, that's the explanation I was asking for earlier!


> Signed-off-by: Wei Chen <wei.chen@arm.com>
> ---
>  xen/arch/arm/numa_device_tree.c | 30 ++++++++++++++++++++++++++++++
>  xen/include/asm-arm/numa.h      |  1 +
>  2 files changed, 31 insertions(+)
> 
> diff --git a/xen/arch/arm/numa_device_tree.c b/xen/arch/arm/numa_device_tree.c
> index e7fa84df4c..6a3fed0002 100644
> --- a/xen/arch/arm/numa_device_tree.c
> +++ b/xen/arch/arm/numa_device_tree.c
> @@ -242,3 +242,33 @@ static int __init fdt_parse_numa_distance_map_v1(const void *fdt, int node)
>  
>      return 0;
>  }
> +
> +static int __init fdt_scan_numa_nodes(const void *fdt,
> +                int node, const char *uname, int depth,
> +                u32 address_cells, u32 size_cells, void *data)

Please align parameters


> +{
> +    int len, ret = 0;
> +    const void *prop;
> +
> +    prop = fdt_getprop(fdt, node, "device_type", &len);
> +    if (prop)

code style


> +    {
> +        len += 1;
> +        if ( memcmp(prop, "cpu", len) == 0 )
> +            ret = fdt_parse_numa_cpu_node(fdt, node);
> +        else if ( memcmp(prop, "memory", len) == 0 )
> +            ret = fdt_parse_numa_memory_node(fdt, node, uname,
> +                                address_cells, size_cells);

I realize that with the inclusion of '\0' in the check, the usage of
memcmp should be safe, but I would prefer if we used strncmp instead.


> +    }
> +    else if ( fdt_node_check_compatible(fdt, node,
> +                                "numa-distance-map-v1") == 0 )
> +        ret = fdt_parse_numa_distance_map_v1(fdt, node);
> +
> +    return ret;
> +}
> +
> +/* Initialize NUMA from device tree */
> +int __init numa_device_tree_init(const void *fdt)
> +{
> +    return device_tree_for_each_node(fdt, 0, fdt_scan_numa_nodes, NULL);
> +}
> diff --git a/xen/include/asm-arm/numa.h b/xen/include/asm-arm/numa.h
> index 7675012cb7..f46e8e2935 100644
> --- a/xen/include/asm-arm/numa.h
> +++ b/xen/include/asm-arm/numa.h
> @@ -23,6 +23,7 @@ typedef u8 nodeid_t;
>  #define NR_NODE_MEMBLKS NR_MEM_BANKS
>  
>  extern void numa_set_distance(nodeid_t from, nodeid_t to, uint32_t distance);
> +extern int numa_device_tree_init(const void *fdt);
>  
>  #else
>  
> -- 
> 2.25.1
>