Re: [XEN RFC PATCH 22/40] xen/arm: introduce a helper to parse device tree processor node

[Julien Grall <julien@xxxxxxx>]

Hi Wei,

On 11/08/2021 11:24, Wei Chen wrote:
> Processor NUMA ID information is stored in device tree's processor
> node as "numa-node-id". We need a new helper to parse this ID from
> processor node. If we get this ID from processor node, this ID's
> validity still need to be checked. Once we got a invalid NUMA ID
> from any processor node, the device tree will be marked as NUMA
> information invalid.
>
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> ---
>   xen/arch/arm/numa_device_tree.c | 41 +++++++++++++++++++++++++++++++--
>   1 file changed, 39 insertions(+), 2 deletions(-)
>
> diff --git a/xen/arch/arm/numa_device_tree.c b/xen/arch/arm/numa_device_tree.c
> index 1c74ad135d..37cc56acf3 100644
> --- a/xen/arch/arm/numa_device_tree.c
> +++ b/xen/arch/arm/numa_device_tree.c
> @@ -20,16 +20,53 @@
>   #include <xen/init.h>
>   #include <xen/nodemask.h>
>   #include <xen/numa.h>
> +#include <xen/device_tree.h>
> +#include <asm/setup.h>
>   
>   s8 device_tree_numa = 0;
> +static nodemask_t processor_nodes_parsed __initdata;
>   
> -int srat_disabled(void)
> +static int srat_disabled(void)
>   {
>       return numa_off || device_tree_numa < 0;
>   }
>   
> -void __init bad_srat(void)
> +static __init void bad_srat(void)
>   {
>       printk(KERN_ERR "DT: NUMA information is not used.\n");
>       device_tree_numa = -1;
>   }
> +
> +/* Callback for device tree processor affinity */
> +static int __init dtb_numa_processor_affinity_init(nodeid_t node)
> +{
> +    if ( srat_disabled() )
> +        return -EINVAL;
> +    else if ( node == NUMA_NO_NODE || node >= MAX_NUMNODES ) {
> +               bad_srat();
> +               return -EINVAL;
You seem to have a mix of soft and hard tab in this file. Is there a lot 
of the code that was directly copied from Linux? If not, then the file 
should be using Xen coding style.
> +       }
> +
> +    node_set(node, processor_nodes_parsed);
> +
> +    device_tree_numa = 1;
> +    printk(KERN_INFO "DT: NUMA node %u processor parsed\n", node);
> +
> +    return 0;
> +}
> +
> +/* Parse CPU NUMA node info */
> +int __init device_tree_parse_numa_cpu_node(const void *fdt, int node)
AFAICT, you are going to turn this helper static in a follow-up patch. 
This is a bad practice. Instead, the function should be static from the 
beginning. If it is not possible, then you should re-order the code.
In this case, I think you can add the boilerplate to parse the NUMA 
information (patch #25) here and then extend it in each patch.

> +{
> +    uint32_t nid;
> +
> +    nid = device_tree_get_u32(fdt, node, "numa-node-id", MAX_NUMNODES);
> +    printk(XENLOG_WARNING "CPU on NUMA node:%u\n", nid);
> +    if ( nid >= MAX_NUMNODES )
> +    {
> +        printk(XENLOG_WARNING "Node id %u exceeds maximum value\n", nid);
> +        return -EINVAL;
> +    }
> +
> +    return dtb_numa_processor_affinity_init(nid);
> +}
Cheers,

--
Julien Grall