linux-kernel - Re: [PATCH -V2] tdx, memory hotplug: Check whole hot-adding memory range for TDX

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4bc038a4-e8ff-4441-acb1-63fcb3dc9068@redhat.com>
Date: Fri, 11 Oct 2024 11:48:24 +0200
From: David Hildenbrand <david@...hat.com>
To: "Huang, Ying" <ying.huang@...el.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>, x86@...nel.org,
 linux-coco@...ts.linux.dev, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, Dan Williams <dan.j.williams@...el.com>,
 Kai Huang <kai.huang@...el.com>, "H. Peter Anvin" <hpa@...or.com>,
 Andy Lutomirski <luto@...nel.org>, Oscar Salvador <osalvador@...e.de>
Subject: Re: [PATCH -V2] tdx, memory hotplug: Check whole hot-adding memory
 range for TDX

On 11.10.24 10:51, Huang, Ying wrote:
> David Hildenbrand <david@...hat.com> writes:
> 
>> On 11.10.24 03:27, Huang, Ying wrote:
>>> David Hildenbrand <david@...hat.com> writes:
>>>
>>>>>     extern u64 max_mem_size;
>>>>>       extern int mhp_online_type_from_str(const char *str);
>>>>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>>>>> index 621ae1015106..c4769f24b1e2 100644
>>>>> --- a/mm/memory_hotplug.c
>>>>> +++ b/mm/memory_hotplug.c
>>>>> @@ -1305,6 +1305,11 @@ int try_online_node(int nid)
>>>>>     	return ret;
>>>>>     }
>>>>>     +int __weak arch_check_hotplug_memory_range(u64 start, u64 size)
>>>>> +{
>>>>> +	return 0;
>>>>> +}
>>>>
>>>> BTW, I remember that "__weak" doesn't always behave the way it would
>>>> seem, which is the reason we're usually using
>>>>
>>>> #define arch_check_hotplug_memory_range arch_check_hotplug_memory_range
>>>>
>>>> #ifndef arch_check_hotplug_memory_range
>>>> ...
>>>> #endif
>>>>
>>>>
>>>> Not that I remember the details, just that it can result in rather
>>>> surprising outcomes (e.g., the wrong function getting called).
>>> I can replace __weak with #define/#ifndef.
>>> However, it appears that "__weak" is still widely used now.
>>
>> Probably better to avoid new ones.
> 
> Sure.  Will do that in the future versions.
> 
>> See also
>> Documentation/dev-tools/checkpatch.rst
>>
>> I assume checkpatch.pl should complain as well?
> 
> Double checked again.  It doesn't complain for that.

Indeed, it only checks for usage of "weak" for *declarations*. So maybe 
it's fine after all and I am misremembering things. So just leave it as 
is for the time being.

-- 
Cheers,

David / dhildenb