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

[Zhao Liu]

On Wed, May 31, 2023 at 05:46:48PM +0200, Igor Mammedov wrote:
> Date: Wed, 31 May 2023 17:46:48 +0200
> From: Igor Mammedov <imammedo@redhat.com>
> Subject: Re: [PATCH 3/3] hw/smbios: Fix core count in type4
> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-redhat-linux-gnu)
> 
> On Tue, 30 May 2023 00:43:43 +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.
> > 
> > [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>
> > ---
> >  hw/smbios/smbios.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/hw/smbios/smbios.c b/hw/smbios/smbios.c
> > index f80a701cdfc1..32e26bffa2df 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 cpus_per_socket = ms->smp.max_cpus / ms->smp.sockets;
> > +    unsigned cores_per_socket = cpus_per_socket / ms->smp.threads;
> wouldn't be
>    smp.dies * smp.clusters * smp.cores
> cleaner and more self-describing
> 
> and then you can add sanity check 
>       g_assert(cores_per_socket != (cpus_per_socket / ms->smp.threads))
> so we won't miss change to CpuTopology in the future?

Thanks! Will use this way.

Regards,
Zhao

>  
> >  
> >      if (smbios_ep_type == SMBIOS_ENTRY_POINT_TYPE_64) {
> >          tbl_len = SMBIOS_TYPE_4_LEN_V30;
> > @@ -748,7 +749,7 @@ static void smbios_build_type_4_table(MachineState *ms, 
> > unsigned instance)
> >      SMBIOS_TABLE_SET_STR(4, asset_tag_number_str, type4.asset);
> >      SMBIOS_TABLE_SET_STR(4, part_number_str, type4.part);
> >  
> > -    t->core_count = (ms->smp.cores > 255) ? 0xFF : ms->smp.cores;
> > +    t->core_count = (cores_per_socket > 255) ? 0xFF : cores_per_socket;
> >      t->core_enabled = t->core_count;
> >  
> >      t->thread_count = (cpus_per_socket > 255) ? 0xFF : cpus_per_socket;
> > @@ -757,7 +758,7 @@ 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(cpus_per_socket);
> >      }
> >  
>