On Mon, Sep 20, 2021 at 02:49:47PM -0300, Daniel Henrique Barboza wrote:
> numa_complete_configuration() in hw/core/numa.c always adds a NUMA node
> for the pSeries machine if none was specified, but without node distance
> information for the single node created.
>
> NUMA FORM1 affinity code didn't rely on numa_state information to do its
> job, but FORM2 does. As is now, this is the result of a pSeries guest
> with NUMA FORM2 affinity when no NUMA nodes is specified:
>
> $ numactl -H
> available: 1 nodes (0)
> node 0 cpus: 0
> node 0 size: 16222 MB
> node 0 free: 15681 MB
> No distance information available.
>
> This can be amended in spapr_numa_FORM2_write_rtas_tables(). We're
> enforcing that the local distance (the distance to the node to itself) is
> always 10. This allows for the proper creation of the NUMA distance tables,
> fixing the output of 'numactl -H' in the guest:
>
> $ numactl -H
> available: 1 nodes (0)
> node 0 cpus: 0
> node 0 size: 16222 MB
> node 0 free: 15685 MB
> node distances:
> node 0
> 0: 10
>
> CC: Igor Mammedov <imammedo@redhat.com>
> Reviewed-by: Greg Kurz <groug@kaod.org>
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> ---
> hw/ppc/spapr_numa.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c
> index 13db321997..58d5dc7084 100644
> --- a/hw/ppc/spapr_numa.c
> +++ b/hw/ppc/spapr_numa.c
> @@ -539,6 +539,17 @@ static void spapr_numa_FORM2_write_rtas_tables(SpaprMachineState *spapr,
>
> for (src = 0; src < nb_numa_nodes; src++) {
> for (dst = 0; dst < nb_numa_nodes; dst++) {
> + /*
> + * We need to be explicit with the local distance
> + * value to cover the case where the user didn't added any
> + * NUMA nodes, but QEMU adds the default NUMA node without
> + * adding the numa_info to retrieve distance info from.
> + */
> + if (src == dst) {
> + node_distances[i++] = 10;
Would it make sense to use NUMA_DISTANCE_MIN here, rather than a fixed
value?
Again, simple enough that it can be fixed in followup.
> + continue;
> + }
> +
> node_distances[i++] = numa_info[src].distance[dst];
> }
> }
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
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