Re: [PATCH v2 3/3] hw/smbios: Fix core count in type4

[Igor Mammedov <imammedo@redhat.com>]

On Thu,  1 Jun 2023 17:29:52 +0800
Zhao Liu <zhao1.liu@linux.intel.com> wrote:

> From: Zhao Liu <zhao1.liu@intel.com>
> 
> From SMBIOS 3.0 specification, core count field means:
> 
> Core Count is the number of cores detected by the BIOS for this
> processor socket. [1]
> 
> Before 003f230e37d7 ("machine: Tweak the order of topology members in
> struct CpuTopology"), MachineState.smp.cores means "the number of cores
> in one package", and it's correct to use smp.cores for core count.
> 
> But 003f230e37d7 changes the smp.cores' meaning to "the number of cores
> in one die" and doesn't change the original smp.cores' use in smbios as
> well, which makes core count in type4 go wrong.
> 
> Fix this issue with the correct "cores per socket" caculation.

see comment on 2/3 patch and do the same for cores.

> 
> [1] SMBIOS 3.0.0, section 7.5.6, Processor Information - Core Count
> 
> Fixes: 003f230e37d7 ("machine: Tweak the order of topology members in struct CpuTopology")
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> ---
> Changes since v1:
>  * Calculate cores_per_socket in a different way from
>    threads_per_socket.
>  * Add the sanity check to ensure consistency of results between these 2
>    ways. This can help not miss any future change of cpu topology.
> ---
>  hw/smbios/smbios.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/smbios/smbios.c b/hw/smbios/smbios.c
> index faf82d4ae646..2b46a51dfcad 100644
> --- a/hw/smbios/smbios.c
> +++ b/hw/smbios/smbios.c
> @@ -714,6 +714,7 @@ static void smbios_build_type_4_table(MachineState *ms, unsigned instance)
>      char sock_str[128];
>      size_t tbl_len = SMBIOS_TYPE_4_LEN_V28;
>      unsigned threads_per_socket;
> +    unsigned cores_per_socket;
>  
>      if (smbios_ep_type == SMBIOS_ENTRY_POINT_TYPE_64) {
>          tbl_len = SMBIOS_TYPE_4_LEN_V30;
> @@ -750,8 +751,16 @@ static void smbios_build_type_4_table(MachineState *ms, unsigned instance)
>  
>      /* smp.max_cpus is the total number of threads for the system. */
>      threads_per_socket = ms->smp.max_cpus / ms->smp.sockets;
> +    cores_per_socket = ms->smp.cores * ms->smp.clusters * ms->smp.dies;
>  
> -    t->core_count = (ms->smp.cores > 255) ? 0xFF : ms->smp.cores;
> +    /*
> +     * Currently, max_cpus = threads * cores * clusters * dies * sockets.
> +     * threads_per_socket and cores_per_socket are calculated in 2 ways so
> +     * that this sanity check ensures we won't miss any topology level.
> +     */
> +    g_assert(cores_per_socket == (threads_per_socket / ms->smp.threads));
> +
> +    t->core_count = (cores_per_socket > 255) ? 0xFF : cores_per_socket;
>      t->core_enabled = t->core_count;
>  
>      t->thread_count = (threads_per_socket > 255) ? 0xFF : threads_per_socket;
> @@ -760,7 +769,7 @@ static void smbios_build_type_4_table(MachineState *ms, unsigned instance)
>      t->processor_family2 = cpu_to_le16(0x01); /* Other */
>  
>      if (tbl_len == SMBIOS_TYPE_4_LEN_V30) {
> -        t->core_count2 = t->core_enabled2 = cpu_to_le16(ms->smp.cores);
> +        t->core_count2 = t->core_enabled2 = cpu_to_le16(cores_per_socket);
>          t->thread_count2 = cpu_to_le16(threads_per_socket);
>      }
>