Re: [RFC PATCH 2/6] acpi: numa: Add support to enumerate and store extended linear address mode

[Dave Jiang <dave.jiang@intel.com>]

On 10/17/24 9:00 AM, Jonathan Cameron wrote:
> On Fri, 27 Sep 2024 07:16:54 -0700
> Dave Jiang <dave.jiang@intel.com> wrote:
> 
>> Store the address mode as part of the cache attriutes. Export the mode
>> attribute to sysfs as all other cache attributes.
>>
>> Link: https://lore.kernel.org/linux-cxl/668333b17e4b2_5639294fd@dwillia2-xfh.jf.intel.com.notmuch/
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> Minor things inline. Basically looks fine.
> 
> Jonathan
> 
>> ---
>>  Documentation/ABI/stable/sysfs-devices-node | 7 +++++++
>>  drivers/acpi/numa/hmat.c                    | 3 +++
>>  drivers/base/node.c                         | 2 ++
>>  include/linux/node.h                        | 7 +++++++
>>  4 files changed, 19 insertions(+)
>>
>> diff --git a/Documentation/ABI/stable/sysfs-devices-node b/Documentation/ABI/stable/sysfs-devices-node
>> index 402af4b2b905..9016cc4f027c 100644
>> --- a/Documentation/ABI/stable/sysfs-devices-node
>> +++ b/Documentation/ABI/stable/sysfs-devices-node
>> @@ -177,6 +177,13 @@ Description:
>>  		The cache write policy: 0 for write-back, 1 for write-through,
>>  		other or unknown.
>>  
>> +What:		/sys/devices/system/node/nodeX/memory_side_cache/indexY/mode
>> +Date:		September 2024
>> +Contact:	Dave Jiang <dave.jiang@intel.com>
>> +Description:
>> +		The address mode: 0 for reserved, 1 for extended-lniear,
> 
> linear
> 
> also, is 0 reserved or unknown? I'm confused.

It's labeled Reserved and indicates unknown in the document.

0 - Reserved (Unknown Address Mode)

I'll just remove "others unknown" line and have 0 as reserved and as well have the define as RESERVED below.

DJ

> 
> 
>> +		other unknown.
>> +
>>  What:		/sys/devices/system/node/nodeX/x86/sgx_total_bytes
>>  Date:		November 2021
>>  Contact:	Jarkko Sakkinen <jarkko@kernel.org>
>> diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c
>> index 1a902a02390f..39524f36be5b 100644
>> --- a/drivers/acpi/numa/hmat.c
>> +++ b/drivers/acpi/numa/hmat.c
>> @@ -506,6 +506,9 @@ static __init int hmat_parse_cache(union acpi_subtable_headers *header,
>>  	switch ((attrs & ACPI_HMAT_CACHE_ASSOCIATIVITY) >> 8) {
>>  	case ACPI_HMAT_CA_DIRECT_MAPPED:
>>  		tcache->cache_attrs.indexing = NODE_CACHE_DIRECT_MAP;
>> +		/* Extended Linear mode is only valid if cache is direct mapped */
>> +		if (cache->address_mode == ACPI_HMAT_CACHE_MODE_EXTENDED_LINEAR)
>> +			tcache->cache_attrs.mode = NODE_CACHE_MODE_EXTENDED_LINEAR;
>>  		break;
>>  	case ACPI_HMAT_CA_COMPLEX_CACHE_INDEXING:
>>  		tcache->cache_attrs.indexing = NODE_CACHE_INDEXED;
>> diff --git a/drivers/base/node.c b/drivers/base/node.c
>> index eb72580288e6..744be5470728 100644
>> --- a/drivers/base/node.c
>> +++ b/drivers/base/node.c
>> @@ -244,12 +244,14 @@ CACHE_ATTR(size, "%llu")
>>  CACHE_ATTR(line_size, "%u")
>>  CACHE_ATTR(indexing, "%u")
>>  CACHE_ATTR(write_policy, "%u")
>> +CACHE_ATTR(mode, "%u")
>>  
>>  static struct attribute *cache_attrs[] = {
>>  	&dev_attr_indexing.attr,
>>  	&dev_attr_size.attr,
>>  	&dev_attr_line_size.attr,
>>  	&dev_attr_write_policy.attr,
>> +	&dev_attr_mode.attr,
>>  	NULL,
>>  };
>>  ATTRIBUTE_GROUPS(cache);
>> diff --git a/include/linux/node.h b/include/linux/node.h
>> index 9a881c2208b3..589951c5e36f 100644
>> --- a/include/linux/node.h
>> +++ b/include/linux/node.h
>> @@ -57,6 +57,11 @@ enum cache_write_policy {
>>  	NODE_CACHE_WRITE_OTHER,
>>  };
>>  
>> +enum cache_mode {
>> +	NODE_CACHE_MODE_UNKOWN,
> UNKNOWN
> 
>> +	NODE_CACHE_MODE_EXTENDED_LINEAR,
>> +};
>> +
>>  /**
>>   * struct node_cache_attrs - system memory caching attributes
>>   *
>> @@ -65,6 +70,7 @@ enum cache_write_policy {
>>   * @size:		Total size of cache in bytes
>>   * @line_size:		Number of bytes fetched on a cache miss
>>   * @level:		The cache hierarchy level
>> + * @mode:		The address mode
>>   */
>>  struct node_cache_attrs {
>>  	enum cache_indexing indexing;
>> @@ -72,6 +78,7 @@ struct node_cache_attrs {
>>  	u64 size;
>>  	u16 line_size;
>>  	u8 level;
>> +	u16 mode;
>>  };
>>  
>>  #ifdef CONFIG_HMEM_REPORTING
>