Re: [PATCH v9 2/9] mm/mmzone: Tag pg_data_t with crypto capabilities

[Martin Fernandez <martin.fernandez@eclypsium.com>]

On 10/7/22, Kirill A. Shutemov <kirill@shutemov.name> wrote:
> On Mon, Jul 04, 2022 at 10:58:26AM -0300, Martin Fernandez wrote:
>> Add a new member in the pg_data_t struct to tell whether the node
>> corresponding to that pg_data_t is able to do hardware memory
>> encryption.
>>
>> This will be read from sysfs.
>>
>> Signed-off-by: Martin Fernandez <martin.fernandez@eclypsium.com>
>> ---
>>  include/linux/mmzone.h | 3 +++
>>  mm/page_alloc.c        | 1 +
>>  2 files changed, 4 insertions(+)
>>
>> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
>> index aab70355d64f..6fd4785f1d05 100644
>> --- a/include/linux/mmzone.h
>> +++ b/include/linux/mmzone.h
>> @@ -883,6 +883,9 @@ typedef struct pglist_data {
>>  	struct task_struct *kcompactd;
>>  	bool proactive_compact_trigger;
>>  #endif
>> +
>> +	bool crypto_capable;
>> +
>
> There's already pgdat->flags. Any reason we cannot encode it there?

Not really a reason, I'll considerate when I send then next version. I
tried to quickly find for references of what kind of flags does it
have, I didn't find any. Do you suggest it should work?

>>  	/*
>>  	 * This is a per-node reserve of pages that are not available
>>  	 * to userspace allocations.
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index e008a3df0485..147437329ac7 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -7729,6 +7729,7 @@ static void __init free_area_init_node(int nid)
>>  	pgdat->node_id = nid;
>>  	pgdat->node_start_pfn = start_pfn;
>>  	pgdat->per_cpu_nodestats = NULL;
>> +	pgdat->crypto_capable = memblock_node_is_crypto_capable(nid);
>>
>>  	if (start_pfn != end_pfn) {
>>  		pr_info("Initmem setup node %d [mem %#018Lx-%#018Lx]\n", nid,
>> --
>> 2.30.2
>>
>
> --
>   Kiryl Shutsemau / Kirill A. Shutemov
>