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

[Tianrui Zhao]

在 2023年05月31日 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
>
> Thanks,
> Zhao
Thanks for your explanations for  the meaning of the number of threads 
per socket, I look up the relevant code again and I agree with your 
patch [1].

Thanks
Tianrui 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