Messages in this thread | | | Subject | Re: [PATCH v2 2/2] ACPI/PPTT: Handle architecturally unknown cache types | From | Jeremy Linton <> | Date | Mon, 17 Sep 2018 17:59:19 -0500 |
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Hi,
On 09/17/2018 05:46 PM, Jeffrey Hugo wrote: > On 9/17/2018 10:17 AM, Sudeep Holla wrote: >> >> >> On 14/09/18 17:28, 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 | 15 +++++++++++---- >>> 1 file changed, 11 insertions(+), 4 deletions(-) >>> >>> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c >>> index d1e26cb..bb00ed9 100644 >>> --- a/drivers/acpi/pptt.c >>> +++ b/drivers/acpi/pptt.c >>> @@ -402,11 +402,18 @@ 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 either the cache has >>> + * been fully specified in PPTT, or 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) >>> + if ((this_leaf->type == CACHE_TYPE_NOCACHE) && >>> + (valid_flags == PPTT_CHECKED_ATTRIBUTES || >>> + found_cache->flags & ACPI_PPTT_CACHE_TYPE_VALID)) >>> this_leaf->type = CACHE_TYPE_UNIFIED; >> >> I thought I did mention that we can drop the valid_flags altogether >> unless Jeremy has reasons not to. >> > > You suggested that perhaps that could be the case. It seemed like an > open question to me. I'm at Linaro Connect without access to the device > this week, so I guess someone has roughly a week to chime in that the > valid flags should be kept, otherwise I'll try a v3 with them removed. >
The point of the valid_flags/CHECKED_ATTRIBUTE was to help assure that a minimum set of attributes were being provided by the firmware. If we are going to reset the CACHE_TYPE, then we might as well remove the valid_flag/CHECKED_ATTRIBUTE counts as it can be easily bypassed.
So, yes please, remove the valid_flags with this change.
Thanks,
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