Re: [Qemu-devel] [RFC PATCH v0] numa: API to lookup NUMA node by address

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

CC'ing Eduardo...

Does this approach look sane ? Currently only PowerPC needs this, however
is this API correct from other architectures' perspective ?

On Thu, May 07, 2015 at 12:34:24PM +0530, Bharata B Rao wrote:
> Keep track of start and end address of each NUMA node in numa_info
> structure so that lookup of node by address becomes easier. Add
> an API numa_get_node() to lookup a node by address.
> 
> This is needed by sPAPR PowerPC to support
> ibm,dynamic-reconfiguration-memory device tree node which is needed for
> memory hotplug.
> 
> Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> ---
> This patch was earlier posted as part of sPAPR hotplug patchset here:
> https://lists.gnu.org/archive/html/qemu-ppc/2015-04/msg00204.html
> 
>  include/sysemu/numa.h |  3 +++
>  numa.c                | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 64 insertions(+)
> 
> diff --git a/include/sysemu/numa.h b/include/sysemu/numa.h
> index 6523b4d..19c0ba3 100644
> --- a/include/sysemu/numa.h
> +++ b/include/sysemu/numa.h
> @@ -15,11 +15,14 @@ typedef struct node_info {
>      DECLARE_BITMAP(node_cpu, MAX_CPUMASK_BITS);
>      struct HostMemoryBackend *node_memdev;
>      bool present;
> +    ram_addr_t mem_start;
> +    ram_addr_t mem_end;
>  } NodeInfo;
>  extern NodeInfo numa_info[MAX_NODES];
>  void parse_numa_opts(MachineClass *mc);
>  void numa_post_machine_init(void);
>  void query_numa_node_mem(uint64_t node_mem[]);
>  extern QemuOptsList qemu_numa_opts;
> +uint32_t numa_get_node(ram_addr_t addr, Error **errp);
> 
>  #endif
> diff --git a/numa.c b/numa.c
> index c975fb2..fdf333b 100644
> --- a/numa.c
> +++ b/numa.c
> @@ -53,6 +53,63 @@ static int max_numa_nodeid; /* Highest specified NUMA node ID, plus one.
>  int nb_numa_nodes;
>  NodeInfo numa_info[MAX_NODES];
> 
> +/*
> + * Given an address, return the index of the NUMA node to which the
> + * address belongs to.
> + */
> +uint32_t numa_get_node(ram_addr_t addr, Error **errp)
> +{
> +    uint32_t i;
> +    MemoryDeviceInfoList *info_list = NULL;
> +    MemoryDeviceInfoList **prev = &info_list;
> +    MemoryDeviceInfoList *info;
> +
> +    for (i = 0; i < nb_numa_nodes; i++) {
> +        if (addr >= numa_info[i].mem_start && addr < numa_info[i].mem_end) {
> +            return i;
> +        }
> +    }
> +
> +    /*
> +     * If this @addr falls under cold or hotplugged memory regions,
> +     * check there too.
> +     */
> +    qmp_pc_dimm_device_list(qdev_get_machine(), &prev);
> +    for (info = info_list; info; info = info->next) {
> +        MemoryDeviceInfo *value = info->value;
> +
> +        if (value) {
> +            switch (value->kind) {
> +            case MEMORY_DEVICE_INFO_KIND_DIMM:
> +                if (addr >= value->dimm->addr &&
> +                        addr < (value->dimm->addr + value->dimm->size)) {
> +                    qapi_free_MemoryDeviceInfoList(info_list);
> +                    return value->dimm->node;
> +                }
> +                break;
> +            default:
> +                break;
> +            }
> +        }
> +    }
> +    qapi_free_MemoryDeviceInfoList(info_list);
> +    error_setg(errp, "Address 0x" RAM_ADDR_FMT " doesn't belong to any "
> +                "NUMA node", addr);
> +
> +    return -1;
> +}
> +
> +static void numa_set_mem_address(int nodenr)
> +{
> +    if (nodenr) {
> +        numa_info[nodenr].mem_start = numa_info[nodenr-1].mem_end;
> +    } else {
> +        numa_info[nodenr].mem_start = 0;
> +    }
> +    numa_info[nodenr].mem_end = numa_info[nodenr].mem_start +
> +                                   numa_info[nodenr].node_mem;
> +}
> +
>  static void numa_node_parse(NumaNodeOptions *node, QemuOpts *opts, Error **errp)
>  {
>      uint16_t nodenr;
> @@ -276,6 +333,10 @@ void parse_numa_opts(MachineClass *mc)
>          }
> 
>          for (i = 0; i < nb_numa_nodes; i++) {
> +            numa_set_mem_address(i);
> +        }
> +
> +        for (i = 0; i < nb_numa_nodes; i++) {
>              if (!bitmap_empty(numa_info[i].node_cpu, MAX_CPUMASK_BITS)) {
>                  break;
>              }
> -- 
> 2.1.0