Re: [PATCH v4 5/8] smp: Move cpu_up/down helpers to common code

[Julien Grall <julien@xxxxxxx>]

Hi,

On 12/11/2025 10:51, Mykyta Poturai wrote:
> This will reduce code duplication for the upcoming cpu hotplug support
> on Arm64 patch.
>
> SMT-disable enforcement check is moved into a separate
> architecture-specific function.
>
> Signed-off-by: Mykyta Poturai <mykyta_poturai@xxxxxxxx>
>
> v3->v4:
> * patch introduced
> ---
>   xen/arch/arm/smp.c             |  6 ++++++
>   xen/arch/ppc/stubs.c           |  4 ++++
>   xen/arch/riscv/stubs.c         |  5 +++++
>   xen/arch/x86/include/asm/smp.h |  3 ---
>   xen/arch/x86/smp.c             | 33 +++------------------------------
>   xen/common/smp.c               | 32 ++++++++++++++++++++++++++++++++
>   xen/include/xen/smp.h          |  4 ++++
>   7 files changed, 54 insertions(+), 33 deletions(-)
>
> diff --git a/xen/arch/arm/smp.c b/xen/arch/arm/smp.c
> index b372472188..85815aeda0 100644
> --- a/xen/arch/arm/smp.c
> +++ b/xen/arch/arm/smp.c
> @@ -44,6 +44,12 @@ void smp_send_call_function_mask(const cpumask_t *mask)
>       }
>   }
>   
> +/* ARM don't have SMT so we don't need any special logic for CPU disabling  */
Xen doesn't support SMT on Arm. But some of the cores may support SMT. 
So would reword this to:
"We currently don't support SMT"

Cheers,

--
Julien Grall