Re: [XEN RFC PATCH 38/40] xen/arm: enable device tree based NUMA in system init

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 11 Aug 2021, Wei Chen wrote:
> Everything is ready, we can remove the fake NUMA node and
> depends on device tree to create NUMA system.
> 
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> ---
>  xen/arch/arm/numa.c        | 45 ++++++++++++++++++++++----------------
>  xen/include/asm-arm/numa.h |  7 ------
>  2 files changed, 26 insertions(+), 26 deletions(-)
> 
> diff --git a/xen/arch/arm/numa.c b/xen/arch/arm/numa.c
> index 2a18c97470..3b04220e60 100644
> --- a/xen/arch/arm/numa.c
> +++ b/xen/arch/arm/numa.c
> @@ -18,6 +18,7 @@
>   *
>   */
>  #include <xen/init.h>
> +#include <xen/device_tree.h>
>  #include <xen/nodemask.h>
>  #include <xen/numa.h>
>  #include <xen/pfn.h>
> @@ -83,28 +84,34 @@ void __init numa_init(bool acpi_off)
>      paddr_t ram_size = 0;
>      paddr_t ram_end = 0;
>  
> -    printk(XENLOG_WARNING
> -        "NUMA has not been supported yet, NUMA off!\n");
> -    /* Arm NUMA has not been implemented until this patch */
> -    numa_off = true;
> +    /* NUMA has been turned off through Xen parameters */
> +    if ( numa_off )
> +        goto mem_init;
>  
> -    /*
> -     * Set all cpu_to_node mapping to 0, this will make cpu_to_node
> -     * function return 0 as previous fake cpu_to_node API.
> -     */
> -    for ( idx = 0; idx < NR_CPUS; idx++ )
> -        cpu_to_node[idx] = 0;
> -
> -    /*
> -     * Make node_to_cpumask, node_spanned_pages and node_start_pfn
> -     * return as previous fake APIs.
> -     */
> -    for ( idx = 0; idx < MAX_NUMNODES; idx++ ) {
> -        node_to_cpumask[idx] = cpu_online_map;
> -        node_spanned_pages(idx) = (max_page - mfn_x(first_valid_mfn));
> -        node_start_pfn(idx) = (mfn_x(first_valid_mfn));
> +    /* Initialize NUMA from device tree when system is not ACPI booted */
> +    if ( acpi_off )
> +    {
> +#ifdef CONFIG_DEVICE_TREE_NUMA
> +        int ret = numa_device_tree_init(device_tree_flattened);
> +        if ( !ret )
> +            goto mem_init;
> +        printk(XENLOG_WARNING
> +               "Init NUMA from device tree failed, ret=%d\n", ret);
> +#else
> +        printk(XENLOG_WARNING
> +               "CONFIG_DEVICE_TREE_NUMA is not set, NUMA off!\n");

I don't think we want to see this warning every time at boot when
CONFIG_DEVICE_TREE_NUMA is off. I'd set it to XENLOG_DEBUG or remove it.

Also given that we have many stub functions in
xen/include/asm-arm/numa.h already, maybe we could also have a stub
function for numa_device_tree_init so that we won'd need an #ifdef
CONFIG_DEVICE_TREE_NUMA here.


> +#endif
> +        numa_off = true;
> +    }
> +    else
> +    {
> +        /* We don't support NUMA for ACPI boot currently */
> +        printk(XENLOG_WARNING
> +               "ACPI NUMA has not been supported yet, NUMA off!\n");
> +        numa_off = true;
>      }
>  
> +mem_init:
>      /*
>       * Find the minimal and maximum address of RAM, NUMA will
>       * build a memory to node mapping table for the whole range.
> diff --git a/xen/include/asm-arm/numa.h b/xen/include/asm-arm/numa.h
> index a3982a94b6..425eb9aede 100644
> --- a/xen/include/asm-arm/numa.h
> +++ b/xen/include/asm-arm/numa.h
> @@ -30,13 +30,6 @@ extern int numa_device_tree_init(const void *fdt);
>  extern void numa_set_distance(nodeid_t from, nodeid_t to, uint32_t distance);
>  extern void arch_numa_init_failed_fallback(void);
>  
> -/*
> - * Temporary for fake NUMA node, when CPU, memory and distance
> - * matrix will be read from DTB or ACPI SRAT. The following
> - * symbols will be removed.
> - */
> -extern mfn_t first_valid_mfn;
> -
>  #else
>  
>  /* Fake one node for now. See also node_online_map. */
> -- 
> 2.25.1
>