Re: [PATCH 6.9.y] x86/topology/amd: Evaluate SMT in CPUID leaf 0x8000001e only on family 0x17 and greater

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Jun 06, 2024 at 04:23:50PM +0200, Christian Heusel wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> The new AMD/HYGON topology parser evaluates the SMT information in CPUID leaf
> 0x8000001e unconditionally while the original code restricted it to CPUs with
> family 0x17 and greater.
> 
> This breaks family 0x15 CPUs which advertise that leaf and have a non-zero
> value in the SMT section. The machine boots, but the scheduler complains loudly
> about the mismatch of the core IDs:
> 
>   WARNING: CPU: 1 PID: 0 at kernel/sched/core.c:6482 sched_cpu_starting+0x183/0x250
>   WARNING: CPU: 0 PID: 1 at kernel/sched/topology.c:2408 build_sched_domains+0x76b/0x12b0
> 
> Add the condition back to cure it.
> 
>   [ bp: Make it actually build because grandpa is not concerned with
>     trivial stuff. :-P ]
> 
> Fixes: f7fb3b2dd92c ("x86/cpu: Provide an AMD/HYGON specific topology parser")
> Closes: https://gitlab.archlinux.org/archlinux/packaging/packages/linux/-/issues/56
> Reported-by: Tim Teichmann <teichmanntim@outlook.de>
> Reported-by: Christian Heusel <christian@heusel.eu>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
> Tested-by: Tim Teichmann <teichmanntim@outlook.de>
> Cc: stable@vger.kernel.org
> Link: https://lore.kernel.org/r/7skhx6mwe4hxiul64v6azhlxnokheorksqsdbp7qw6g2jduf6c@7b5pvomauugk
> (cherry picked from commit 34bf6bae3286a58762711cfbce2cf74ecd42e1b5)
> Signed-off-by: Christian Heusel <christian@heusel.eu>
> ---
>  arch/x86/kernel/cpu/topology_amd.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 

Now queued up, thanks.

greg k-h