Re: [RFC 12/52] hw/acpi: Replace MachineState.smp access with topology helpers

[wangyanan (Y)]

Hi Zhao,

在 2023/2/13 17:49, Zhao Liu 写道:
> From: Zhao Liu <zhao1.liu@intel.com>
>
> At present, in QEMU only arm needs PPTT table to build cpu topology.
>
> Before QEMU's arm supports hybrid architectures, it's enough to limit
> the cpu topology of PPTT to smp type through the explicit smp interface
> (machine_topo_get_smp_threads()).
>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Igor Mammedov <imammedo@redhat.com>
> Cc: Ani Sinha <ani@anisinha.ca>
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> ---
>   hw/acpi/aml-build.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
> index ea331a20d131..693bd8833d10 100644
> --- a/hw/acpi/aml-build.c
> +++ b/hw/acpi/aml-build.c
> @@ -2044,7 +2044,7 @@ void build_pptt(GArray *table_data, BIOSLinker *linker, 
> MachineState *ms,
>               cluster_offset = socket_offset;
>           }
>   
> -        if (ms->smp.threads == 1) {
> +        if (machine_topo_get_smp_threads(ms) == 1) {
>               build_processor_hierarchy_node(table_data,
>                   (1 << 1) | /* ACPI Processor ID valid */
>                   (1 << 3),  /* Node is a Leaf */
ACPI PPTT table is designed to also support the hybrid CPU topology
case where nodes on the same CPU topology level can have different
number of child nodes.

So to be general, the diff should be:
diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
index ea331a20d1..dfded95bbc 100644
--- a/hw/acpi/aml-build.c
+++ b/hw/acpi/aml-build.c
@@ -2044,7 +2044,7 @@ void build_pptt(GArray *table_data, BIOSLinker 
*linker, MachineState *ms,
             cluster_offset = socket_offset;
         }

-        if (ms->smp.threads == 1) {
+        if (machine_topo_get_threads_by_idx(n) == 1) {
             build_processor_hierarchy_node(table_data,
                 (1 << 1) | /* ACPI Processor ID valid */
                 (1 << 3),  /* Node is a Leaf */

Actually I'm recently working on ARM hmp virtualization which relys on
PPTT for topology representation, so we will also need PPTT to be general
for hybrid case anyway.

Thanks,
Yanan