On Wed, 3 Mar 2021 18:48:50 +0100
Cédric Le Goater <c...@kaod.org> wrote:
> The 'chip_id' field of the XIVE CPU structure is used to choose a
> target for a source located on the same chip when possible. This field
> is assigned on the PowerNV platform using the "ibm,chip-id" property
> on pSeries under KVM when NUMA nodes are defined but it is undefined
This sentence seems to have a syntax problem... like it is missing an
'and' before 'on pSeries'.
> under PowerVM. The XIVE source structure has a similar field
> 'src_chip' which is only assigned on the PowerNV platform.
>
> cpu_to_node() returns a compatible value on all platforms, 0 being the
> default node. It will also give us the opportunity to set the affinity
> of a source on pSeries when we can localize them.
>
IIUC this relies on the fact that the NUMA node id is == to chip id
on PowerNV, i.e. xc->chip_id which is passed to OPAL remain stable
with this change.
On the other hand, you have the pSeries case under PowerVM that
doesn't xc->chip_id, which isn't passed to any hcall AFAICT. It
looks like the chip id is only used for localization purpose in
this case, right ?
In this case, what about doing this change for pSeries only,
somewhere in spapr.c ?
> Signed-off-by: Cédric Le Goater <c...@kaod.org>
> ---
> arch/powerpc/sysdev/xive/common.c | 7 +------
> 1 file changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/sysdev/xive/common.c
> b/arch/powerpc/sysdev/xive/common.c
> index 595310e056f4..b8e456da28aa 100644
> --- a/arch/powerpc/sysdev/xive/common.c
> +++ b/arch/powerpc/sysdev/xive/common.c
> @@ -1335,16 +1335,11 @@ static int xive_prepare_cpu(unsigned int cpu)
>
> xc = per_cpu(xive_cpu, cpu);
> if (!xc) {
> - struct device_node *np;
> -
> xc = kzalloc_node(sizeof(struct xive_cpu),
> GFP_KERNEL, cpu_to_node(cpu));
> if (!xc)
> return -ENOMEM;
> - np = of_get_cpu_node(cpu, NULL);
> - if (np)
> - xc->chip_id = of_get_ibm_chip_id(np);
> - of_node_put(np);
> + xc->chip_id = cpu_to_node(cpu);
> xc->hw_ipi = XIVE_BAD_IRQ;
>
> per_cpu(xive_cpu, cpu) = xc;
