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

[Jeffrey Hugo]

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@xxxxxxxxxxxxxx>
> > Signed-off-by: Jeffrey Hugo <jhugo@xxxxxxxxxxxxxx>
> > ---
> >   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@xxxxxxx>

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.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.