Re: [PATCH 20/22] xen/arm64: mm: Use per-pCPU page-tables

[Julien Grall <julien@xen.org>]

Hi Henry,

On 06/01/2023 14:54, Henry Wang wrote:
>> -----Original Message-----
>> Subject: [PATCH 20/22] xen/arm64: mm: Use per-pCPU page-tables
>>
>> From: Julien Grall <jgrall@amazon.com>
>>
>> At the moment, on Arm64, every pCPU are sharing the same page-tables.
> 
> Nit: s/every pCPU are/ every pCPU is/

I will fix it.

> 
>>
>>   /*
>> diff --git a/xen/arch/arm/include/asm/domain_page.h
>> b/xen/arch/arm/include/asm/domain_page.h
>> new file mode 100644
>> index 000000000000..e9f52685e2ec
>> --- /dev/null
>> +++ b/xen/arch/arm/include/asm/domain_page.h
>> @@ -0,0 +1,13 @@
>> +#ifndef __ASM_ARM_DOMAIN_PAGE_H__
>> +#define __ASM_ARM_DOMAIN_PAGE_H__
>> +
>> +#ifdef CONFIG_ARCH_MAP_DOMAIN_PAGE
>> +bool init_domheap_mappings(unsigned int cpu);
> 
> I wonder if we can make this function "__init" as IIRC this function is only
> used at Xen boot time, but since the original init_domheap_mappings()
> is not "__init" anyway so this is not a strong argument.

While this is not yet supported on Xen on Arm, CPUs can be 
onlined/offlined at runtime. So you want to keep init_domheap_mappings() 
around.

We could consider to provide a new attribute that will be match __init 
if hotplug is supported otherwirse it would be a NOP. But I don't think 
this is related to this series (most of the function used for bringup 
are not in __init).

>> +static inline bool init_domheap_mappings(unsigned int cpu)
> 
> (and also here)
> 
> Either you agree with above "__init" comment or not:
> Reviewed-by: Henry Wang <Henry.Wang@arm.com>

Thanks!

Cheers,

-- 
Julien Grall