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

Sudeep Holla
2018-10-02T10:57:11Z

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>

--
Regards,
Sudeep