Re: [XEN RFC PATCH 36/40] xen/arm: keep guest still be NUMA unware

[Julien Grall <julien@xxxxxxx>]

Hi Wei,

On 11/08/2021 11:24, Wei Chen wrote:
> We have not wanted to make Xen guest be NUMA aware in this patch
> series. 
The concept of patch series ceases to exist once we merge the code. So 
about how:
"The NUMA information provided in the host Device-Tree are only for Xen. 
For dom0, we want to hide them as they may be different (for now, dom0 
is still not aware of NUMA".
> So in this patch, Xen will skip NUMA distance matrix node
> and skip the numa-node-id property in CPU node and memory node,
> when Xen is creating guest device tree binary.
The CPU and memory nodes are recreated from scratch for the domain. So 
we already skip the property numa-node-id. However...
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> ---
>   xen/arch/arm/domain_build.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index cf341f349f..e62fa761bd 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -584,6 +584,10 @@ static int __init write_properties(struct domain *d, 
> struct kernel_info *kinfo,
>                   continue;
>           }
>   
> +        /* Guest is numa unaware in current stage */
> +        if ( dt_property_name_is_equal(prop, "numa-node-id") )
> +            continue;
... your code is doing more than skipping the property for the two nodes 
you mentionned. Can the property exists in other nodes?
> +
>           res = fdt_property(kinfo->fdt, prop->name, prop_data, prop_len);
>   
>           if ( res )
> @@ -1454,6 +1458,8 @@ static int __init handle_node(struct domain *d, struct 
> kernel_info *kinfo,
>           DT_MATCH_TYPE("memory"),
>           /* The memory mapped timer is not supported by Xen. */
>           DT_MATCH_COMPATIBLE("arm,armv7-timer-mem"),
> +        /* Numa info doesn't need to be exposed to Domain-0 */
> +        DT_MATCH_COMPATIBLE("numa-distance-map-v1"),
>           { /* sentinel */ },
>       };
>       static const struct dt_device_match timer_matches[] __initconst =
Cheers,

--
Julien Grall