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

[Zhao Liu]

On Wed, Jun 07, 2023 at 04:51:07PM +0200, Igor Mammedov wrote:
> Date: Wed, 7 Jun 2023 16:51:07 +0200
> From: Igor Mammedov <imammedo@redhat.com>
> Subject: Re: [PATCH v2 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 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.

Ok, thanks.

> 
> > 
> > [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);
> >      }
> >  
>