Re: [Xen-devel] [PATCH for-4.13] x86/AMD: unbreak CPU hotplug on AMD systems without RstrFpErrPtrs

[Jan Beulich <jbeulich@xxxxxxxx>]

On 03.12.2019 15:21, Igor Druzhinin wrote:
> On 03/12/2019 10:08, Jan Beulich wrote:
>> On 29.11.2019 21:01, Igor Druzhinin wrote:
>>> --- a/xen/arch/x86/cpu/common.c
>>> +++ b/xen/arch/x86/cpu/common.c
>>> @@ -54,7 +54,7 @@ static unsigned int forced_caps[NCAPINTS];
>>>  
>>>  DEFINE_PER_CPU(bool, full_gdt_loaded);
>>>  
>>> -void __init setup_clear_cpu_cap(unsigned int cap)
>>> +void setup_clear_cpu_cap(unsigned int cap)
>>>  {
>>>     const uint32_t *dfs;
>>>     unsigned int i;
>>> @@ -83,7 +83,7 @@ void __init setup_clear_cpu_cap(unsigned int cap)
>>>     }
>>>  }
>>>  
>>> -void __init setup_force_cpu_cap(unsigned int cap)
>>> +void setup_force_cpu_cap(unsigned int cap)
>>>  {
>>>     if (__test_and_set_bit(cap, forced_caps))
>>>             return;
>>
>> The two functions are deliberately __init, as any call to them
>> post-init is not going to take system-wide effect. These functions
>> should really be __init_presmp, if we had something like this. No
>> use of them on an AP boot path is going to affect the BSP, and
>> hence will leave the system in an inconsistent state.
> 
> On second thought, looking at how many places actually call 
> setup_{force,clear}_cpu_cap() on AP init path it still makes sense
> to keep the v1 approach as otherwise we will have to manually workaround
> every single place where it happens.

While not all of the other uses of the functions happen from __init
functions, all of them are unreachable on APs afaict - I've just
gone through all instances.

Jan

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel