Re: [PATCH] hw/smbios: fix thead count field in type 4 table

[Zhao Liu]

On Thu, Jun 01, 2023 at 09:09:13AM +0800, bibo, mao wrote:
> Date: Thu, 1 Jun 2023 09:09:13 +0800
> From: "bibo, mao" <maobibo@loongson.cn>
> Subject: Re: [PATCH] hw/smbios: fix thead count field in type 4 table
> 
> 
> 
> 在 2023/5/31 16:42, Zhao Liu 写道:
> > On Tue, May 30, 2023 at 08:20:34PM +0800, Tianrui Zhao wrote:
> > > Date: Tue, 30 May 2023 20:20:34 +0800
> > > From: Tianrui Zhao <zhaotianrui@loongson.cn>
> > > Subject: [PATCH] hw/smbios: fix thead count field in type 4 table
> > > X-Mailer: git-send-email 2.39.1
> > > 
> > > The thread_count value in smbios type_4 table should be
> > > (ms->smp.cores * ms->smp.threads). As according to smbios spec 7.5
> > > Processor Information (Type 4), the field "Thread Count" means the
> > > "Number of threads per processor socket" rather than number of
> > > threads per core.
> > > 
> > > When apply this patch, use "-smp 4,sockets=1,cores=2,threads=2" to
> > > boot VM, the dmidecode -t 4 shows like:
> > > 
> > > Handle 0x0400, DMI type 4, 48 bytes
> > > Processor Information
> > >          Socket Designation: CPU 0
> > >          ...
> > >          Core Count: 2
> > >          Core Enabled: 2
> > >          Thread Count: 4
> > >          Characteristics: None
> > > 
> > > Signed-off-by: Tianrui Zhao <zhaotianrui@loongson.cn>
> > > ---
> > >   hw/smbios/smbios.c | 7 ++++---
> > >   1 file changed, 4 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/hw/smbios/smbios.c b/hw/smbios/smbios.c
> > > index d2007e70fb..56aeaa069d 100644
> > > --- a/hw/smbios/smbios.c
> > > +++ b/hw/smbios/smbios.c
> > > @@ -713,6 +713,7 @@ static void smbios_build_type_4_table(MachineState 
> > > *ms, unsigned instance)
> > >   {
> > >       char sock_str[128];
> > >       size_t tbl_len = SMBIOS_TYPE_4_LEN_V28;
> > > +    int count;
> > >       if (smbios_ep_type == SMBIOS_ENTRY_POINT_TYPE_64) {
> > >           tbl_len = SMBIOS_TYPE_4_LEN_V30;
> > > @@ -749,15 +750,15 @@ static void smbios_build_type_4_table(MachineState 
> > > *ms, unsigned instance)
> > >       t->core_count = (ms->smp.cores > 255) ? 0xFF : ms->smp.cores;
> > >       t->core_enabled = t->core_count;
> > > -
> > > -    t->thread_count = (ms->smp.threads > 255) ? 0xFF : ms->smp.threads;
> > > +    count = ms->smp.cores * ms->smp.threads;
> > 
> > Hi Ani & Tianrui,
> > 
> >  From the comment of CpuTopology (include/hw/boards.h):
> > 
> > ms->cores means the "the number of cores in one cluster".
> > ms->threads means the "the number of threads in one core".
> > 
> > So ms->cores * ms->threads means the number of threads in one cluster
> > not one socket.
> > 
> > That's why I count the number of threads in a socket by "ms->smp.max_cpus
> > / ms->smp.sockets" in [1].
> > 
> > The other correct way is:
> > ms->smp.cluster * ms->smp.cores * ms->smp.threads.
> > 
> > [1]: https://lists.gnu.org/archive/html/qemu-devel/2023-05/msg07229.html
> ohh, we do not notice your patch. Your patch is better than us. one small
> nit about core_count calcuation if cluster/die is support. core count should
> be core number
>  per package rather than per cluster or per die.
> 
> so it should be something like this?
>     t->core_count = cpus_per_socket / ms->smp.threads
> rather than ms->smp.cores

Yes, I also fixed this in the third patch of my patch series [2].

[2]: https://lists.gnu.org/archive/html/qemu-devel/2023-05/msg07231.html

Regards,
Zhao

> 
> 
> Regards
> Bibo, mao
> > 
> > Thanks,
> > Zhao
> > 
> > > +    t->thread_count = (count > 255) ? 0xFF : count;
> > >       t->processor_characteristics = cpu_to_le16(0x02); /* Unknown */
> > >       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->thread_count2 = cpu_to_le16(ms->smp.threads);
> > > +        t->thread_count2 = cpu_to_le16(count);
> > >       }
> > >       SMBIOS_BUILD_TABLE_POST;
> > > -- 
> > > 2.39.1
> > > 
> > > 
> 
>