Re: [PATCH v3 2/2] ACPI/PPTT: Handle architecturally unknown cache types

Jeffrey Hugo
2018-10-02T15:30:21Z

On 10/2/2018 4:57 AM, Sudeep Holla wrote:
> On Thu, Sep 27, 2018 at 08:57:57PM -0600, Jeffrey Hugo wrote:
>> The type of a cache might not be specified by architectural mechanisms (ie
>> system registers), but its type might be specified in the PPTT. In this
>> case, we should populate the type of the cache, rather than leave it
>> undefined.
>>
>> This fixes the issue where the cacheinfo driver will not populate sysfs
>> for such caches, resulting in the information missing from utilities like
>> lstopo and lscpu, thus degrading the user experience.
>>
>> Fixes: 2bd00bcd73e5 (ACPI/PPTT: Add Processor Properties Topology Table parsing)
>> Reported-by: Vijaya Kumar K <vkilari@codeaurora.org>
>> Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
>> ---
>> drivers/acpi/pptt.c | 30 +++++++++++++-----------------
>> 1 file changed, 13 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
>> index d1e26cb..38ac30e 100644
>> --- a/drivers/acpi/pptt.c
>> +++ b/drivers/acpi/pptt.c
>> @@ -357,25 +357,15 @@ static void update_cache_properties(struct cacheinfo *this_leaf,
>> struct acpi_pptt_cache *found_cache,
>> struct acpi_pptt_processor *cpu_node)
>> {
>> - int valid_flags = 0;
>> -
>> this_leaf->fw_token = cpu_node;
>> - if (found_cache->flags & ACPI_PPTT_SIZE_PROPERTY_VALID) {
>> + if (found_cache->flags & ACPI_PPTT_SIZE_PROPERTY_VALID)
>> this_leaf->size = found_cache->size;
>> - valid_flags++;
>> - }
>> - if (found_cache->flags & ACPI_PPTT_LINE_SIZE_VALID) {
>> + if (found_cache->flags & ACPI_PPTT_LINE_SIZE_VALID)
>> this_leaf->coherency_line_size = found_cache->line_size;
>> - valid_flags++;
>> - }
>> - if (found_cache->flags & ACPI_PPTT_NUMBER_OF_SETS_VALID) {
>> + if (found_cache->flags & ACPI_PPTT_NUMBER_OF_SETS_VALID)
>> this_leaf->number_of_sets = found_cache->number_of_sets;
>> - valid_flags++;
>> - }
>> - if (found_cache->flags & ACPI_PPTT_ASSOCIATIVITY_VALID) {
>> + if (found_cache->flags & ACPI_PPTT_ASSOCIATIVITY_VALID)
>> this_leaf->ways_of_associativity = found_cache->associativity;
>> - valid_flags++;
>> - }
>> if (found_cache->flags & ACPI_PPTT_WRITE_POLICY_VALID) {
>> switch (found_cache->attributes & ACPI_PPTT_MASK_WRITE_POLICY) {
>> case ACPI_PPTT_CACHE_POLICY_WT:
>> @@ -402,11 +392,17 @@ static void update_cache_properties(struct cacheinfo *this_leaf,
>> }
>> }
>> /*
>> - * If the above flags are valid, and the cache type is NOCACHE
>> - * update the cache type as well.
>> + * If cache type is NOCACHE, then the cache hasn't been specified
>> + * via other mechanisms. Update the type if a cache type has been
>> + * provided.
>> + *
>> + * Note, we assume such caches are unified based on conventional system
>> + * design and known examples. Significant work is required elsewhere to
>> + * fully support data/instruction only type caches which are only
>> + * specified in PPTT.
>> */
>> if (this_leaf->type == CACHE_TYPE_NOCACHE &&
>> - valid_flags == PPTT_CHECKED_ATTRIBUTES)
>
> I don't think we use PPTT_CHECKED_ATTRIBUTES elsewhere.
> If so, can we drop that ?
>
> Other than that:
> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>

Whoops, you are right. For some reason I thought that came from the
standard ACPICA definitions. Let me drop that.

--
Jeffrey Hugo
Qualcomm Datacenter Technologies as an affiliate of Qualcomm
Technologies, Inc.