Re: [Xen-devel] [PATCH] xen/x86: clear per cpu stub page information in cpu_smpboot_free()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 08.01.2020 14:26, Jürgen Groß wrote:
> On 08.01.20 14:20, Jan Beulich wrote:
>> On 08.01.2020 12:01, Juergen Gross wrote:
>>> --- a/xen/arch/x86/smpboot.c
>>> +++ b/xen/arch/x86/smpboot.c
>>> @@ -945,6 +945,8 @@ static void cpu_smpboot_free(unsigned int cpu, bool 
>>> remove)
>>>                                (per_cpu(stubs.addr, cpu) | ~PAGE_MASK) + 1);
>>>           if ( i == STUBS_PER_PAGE )
>>>               free_domheap_page(mfn_to_page(mfn));
>>> +        per_cpu(stubs.addr, cpu) = 0;
>>> +        per_cpu(stubs.mfn, cpu) = 0;
>>>       }
>>
>> Afaict this was a regression from the introduction of CPU parking:
>> Prior to that, per-CPU data would have been zeroed in all cases
>> before a new CPU was unleashed. I think it would be helpful it
>> this was mentioned in the description (possibly by way of a Fixes:
>> tag).
> 
> Okay, will do. Just to be sure - you are thinking of commit 2e6c8f182?

Yes, this looks to be the one.

Jan

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