Re: [PATCH v3] xen/arm: Set correct per-cpu cpu_core_mask

[Michal Orzel <michal.orzel@xxxxxxx>]

On 21/05/2024 09:51, Henry Wang wrote:
> Hi Michal,
> 
> On 5/21/2024 3:47 PM, Michal Orzel wrote:
>> Hi Henry.
>>
>> On 3/21/2024 11:57 AM, Henry Wang wrote:
>>>> In the common sysctl command XEN_SYSCTL_physinfo, the value of
>>>> cores_per_socket is calculated based on the cpu_core_mask of CPU0.
>>>> Currently on Arm this is a fixed value 1 (can be checked via xl info),
>>>> which is not correct. This is because during the Arm CPU online
>>>> process at boot time, setup_cpu_sibling_map() only sets the per-cpu
>>>> cpu_core_mask for itself.
>>>>
>>>> cores_per_socket refers to the number of cores that belong to the same
>>>> socket (NUMA node). Currently Xen on Arm does not support physical
>>>> CPU hotplug and NUMA, also we assume there is no multithread. Therefore
>>>> cores_per_socket means all possible CPUs detected from the device
>>>> tree. Setting the per-cpu cpu_core_mask in setup_cpu_sibling_map()
>>>> accordingly. Modify the in-code comment which seems to be outdated. Add
>>>> a warning to users if Xen is running on processors with multithread
>>>> support.
>>>>
>>>> Signed-off-by: Henry Wang <Henry.Wang@xxxxxxx>
>>>> Signed-off-by: Henry Wang <xin.wang2@xxxxxxx>
>> Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
> 
> Thanks.
> 
>>>>    /* ID of the PCPU we're running on */
>>>>    DEFINE_PER_CPU(unsigned int, cpu_id);
>>>> -/* XXX these seem awfully x86ish... */
>>>> +/*
>>>> + * Although multithread is part of the Arm spec, there are not many
>>>> + * processors support multithread and current Xen on Arm assumes there
>> NIT: s/support/supporting
> 
> Sorry, it should have been spotted locally before sending. Anyway, I 
> will correct this in v4 with your Reviewed-by tag taken. Thanks for 
> pointing this out.
I don't think there is a need to resend a patch just for fixing this typo. It 
can be done on commit.

~Michal