Re: [PATCH v5 4/4] hw/acpi/aml-build: Use existing CPU topology to build PPTT table

[Igor Mammedov <imammedo@redhat.com>]

On Sun,  3 Apr 2022 22:59:53 +0800
Gavin Shan <gshan@redhat.com> wrote:

> When the PPTT table is built, the CPU topology is re-calculated, but
> it's unecessary because the CPU topology has been populated in
> virt_possible_cpu_arch_ids() on arm/virt machine.
> 
> This reworks build_pptt() to avoid by reusing the existing one in
> ms->possible_cpus. Currently, the only user of build_pptt() is
> arm/virt machine.
> 
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> ---
>  hw/acpi/aml-build.c | 100 +++++++++++++++++---------------------------
>  1 file changed, 38 insertions(+), 62 deletions(-)
> 
> diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
> index 4086879ebf..4b0f9df3e3 100644
> --- a/hw/acpi/aml-build.c
> +++ b/hw/acpi/aml-build.c
> @@ -2002,86 +2002,62 @@ void build_pptt(GArray *table_data, BIOSLinker *linker, MachineState *ms,
>                  const char *oem_id, const char *oem_table_id)
>  {
>      MachineClass *mc = MACHINE_GET_CLASS(ms);
> -    GQueue *list = g_queue_new();
> -    guint pptt_start = table_data->len;
> -    guint parent_offset;
> -    guint length, i;
> -    int uid = 0;
> -    int socket;
> +    CPUArchIdList *cpus = ms->possible_cpus;
> +    int64_t socket_id = -1, cluster_id = -1, core_id = -1;
> +    uint32_t socket_offset, cluster_offset, core_offset;
> +    uint32_t pptt_start = table_data->len;
> +    int n;
>      AcpiTable table = { .sig = "PPTT", .rev = 2,
>                          .oem_id = oem_id, .oem_table_id = oem_table_id };
>  
>      acpi_table_begin(&table, table_data);
>  
> -    for (socket = 0; socket < ms->smp.sockets; socket++) {
> -        g_queue_push_tail(list,
> -            GUINT_TO_POINTER(table_data->len - pptt_start));
> -        build_processor_hierarchy_node(
> -            table_data,
> -            /*
> -             * Physical package - represents the boundary
> -             * of a physical package
> -             */
> -            (1 << 0),
> -            0, socket, NULL, 0);
> -    }
> +    for (n = 0; n < cpus->len; n++) {

> +        if (cpus->cpus[n].props.socket_id != socket_id) {
> +            socket_id = cpus->cpus[n].props.socket_id;

this relies on cpus->cpus[n].props.*_id being sorted form top to down levels
I'd add here and for other container_id an assert() that checks for that
specific ID goes in only one direction, to be able to detect when rule is broken.

otherwise on may end up with duplicate containers silently.

> +            cluster_id = -1;
> +            core_id = -1;
> +            socket_offset = table_data->len - pptt_start;
> +            build_processor_hierarchy_node(table_data,
> +                (1 << 0), /* Physical package */
> +                0, socket_id, NULL, 0);
> +        }
>  
> -    if (mc->smp_props.clusters_supported) {
> -        length = g_queue_get_length(list);
> -        for (i = 0; i < length; i++) {
> -            int cluster;
> -
> -            parent_offset = GPOINTER_TO_UINT(g_queue_pop_head(list));
> -            for (cluster = 0; cluster < ms->smp.clusters; cluster++) {
> -                g_queue_push_tail(list,
> -                    GUINT_TO_POINTER(table_data->len - pptt_start));
> -                build_processor_hierarchy_node(
> -                    table_data,
> -                    (0 << 0), /* not a physical package */
> -                    parent_offset, cluster, NULL, 0);
> +        if (mc->smp_props.clusters_supported) {
> +            if (cpus->cpus[n].props.cluster_id != cluster_id) {
> +                cluster_id = cpus->cpus[n].props.cluster_id;
> +                core_id = -1;
> +                cluster_offset = table_data->len - pptt_start;
> +                build_processor_hierarchy_node(table_data,
> +                    (0 << 0), /* Not a physical package */
> +                    socket_offset, cluster_id, NULL, 0);
>              }
> +        } else {
> +            cluster_offset = socket_offset;
>          }
> -    }
>  
> -    length = g_queue_get_length(list);
> -    for (i = 0; i < length; i++) {
> -        int core;
> -
> -        parent_offset = GPOINTER_TO_UINT(g_queue_pop_head(list));
> -        for (core = 0; core < ms->smp.cores; core++) {
> -            if (ms->smp.threads > 1) {
> -                g_queue_push_tail(list,
> -                    GUINT_TO_POINTER(table_data->len - pptt_start));
> -                build_processor_hierarchy_node(
> -                    table_data,
> +        if (ms->smp.threads <= 1) {

why <= instead of < is used here?

> +            build_processor_hierarchy_node(table_data,
> +                (1 << 1) | /* ACPI Processor ID valid */
> +                (1 << 3),  /* Node is a Leaf */
> +                cluster_offset, n, NULL, 0);
> +        } else {
> +            if (cpus->cpus[n].props.core_id != core_id) {
> +                core_id = cpus->cpus[n].props.core_id;
> +                core_offset = table_data->len - pptt_start;
> +                build_processor_hierarchy_node(table_data,
>                      (0 << 0), /* not a physical package */
> -                    parent_offset, core, NULL, 0);
> -            } else {
> -                build_processor_hierarchy_node(
> -                    table_data,
> -                    (1 << 1) | /* ACPI Processor ID valid */
> -                    (1 << 3),  /* Node is a Leaf */
> -                    parent_offset, uid++, NULL, 0);
> +                    cluster_offset, core_id, NULL, 0);
>              }
> -        }
> -    }
> -
> -    length = g_queue_get_length(list);
> -    for (i = 0; i < length; i++) {
> -        int thread;
>  
> -        parent_offset = GPOINTER_TO_UINT(g_queue_pop_head(list));
> -        for (thread = 0; thread < ms->smp.threads; thread++) {
> -            build_processor_hierarchy_node(
> -                table_data,
> +            build_processor_hierarchy_node(table_data,
>                  (1 << 1) | /* ACPI Processor ID valid */
>                  (1 << 2) | /* Processor is a Thread */
>                  (1 << 3),  /* Node is a Leaf */
> -                parent_offset, uid++, NULL, 0);
> +                core_offset, n, NULL, 0);
>          }
>      }
>  
> -    g_queue_free(list);
>      acpi_table_end(linker, &table);
>  }
>