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

[Jonathan Cameron]

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>

Hi Gavin,

My compiler isn't being very smart today and gives a bunch of
maybe used uninitialized for socket_offset, cluster_offset and core_offset.

They probably are initialized in all real paths, but I think you need to
set them to something at instantiation to keep the compiler happy.

Thanks,

Jonathan

> ---
>  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;
> +            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) {
> +            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);
>  }
>