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Message-ID: <ed7f2e82-1e9b-9f46-89af-4e638275355d@caviumnetworks.com>
Date: Wed, 18 Oct 2017 12:24:35 +0200
From: Tomasz Nowicki <tnowicki@...iumnetworks.com>
To: Tomasz Nowicki <tnowicki@...iumnetworks.com>,
Jeremy Linton <jeremy.linton@....com>,
linux-acpi@...r.kernel.org
Cc: mark.rutland@....com, Jonathan.Zhang@...ium.com,
Jayachandran.Nair@...ium.com, lorenzo.pieralisi@....com,
austinwc@...eaurora.org, linux-pm@...r.kernel.org,
jhugo@...eaurora.org, gregkh@...uxfoundation.org,
sudeep.holla@....com, rjw@...ysocki.net,
linux-kernel@...r.kernel.org, will.deacon@....com,
wangxiongfeng2@...wei.com, viresh.kumar@...aro.org,
hanjun.guo@...aro.org, catalin.marinas@....com, ahs3@...hat.com,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 1/7] ACPI/PPTT: Add Processor Properties Topology Table
parsing
On 18.10.2017 07:39, Tomasz Nowicki wrote:
> Hi,
>
> On 17.10.2017 17:22, Jeremy Linton wrote:
>> Hi,
>>
>> On 10/17/2017 08:25 AM, Tomasz Nowicki wrote:
>>> Hi Jeremy,
>>>
>>> I did second round of review and have some more comments, please see
>>> below:
>>>
>>> On 12.10.2017 21:48, Jeremy Linton wrote:
>>>> ACPI 6.2 adds a new table, which describes how processing units
>>>> are related to each other in tree like fashion. Caches are
>>>> also sprinkled throughout the tree and describe the properties
>>>> of the caches in relation to other caches and processing units.
>>>>
>>>> Add the code to parse the cache hierarchy and report the total
>>>> number of levels of cache for a given core using
>>>> acpi_find_last_cache_level() as well as fill out the individual
>>>> cores cache information with cache_setup_acpi() once the
>>>> cpu_cacheinfo structure has been populated by the arch specific
>>>> code.
>>>>
>>>> Further, report peers in the topology using setup_acpi_cpu_topology()
>>>> to report a unique ID for each processing unit at a given level
>>>> in the tree. These unique id's can then be used to match related
>>>> processing units which exist as threads, COD (clusters
>>>> on die), within a given package, etc.
>>>>
>>>> Signed-off-by: Jeremy Linton <jeremy.linton@....com>
>>>> ---
>>>> drivers/acpi/pptt.c | 485
>>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>> 1 file changed, 485 insertions(+)
>>>> create mode 100644 drivers/acpi/pptt.c
>>>>
>>>> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
>>>> new file mode 100644
>>>> index 000000000000..c86715fed4a7
>>>> --- /dev/null
>>>> +++ b/drivers/acpi/pptt.c
>>>> @@ -0,1 +1,485 @@
>>>> +/*
>>>> + * Copyright (C) 2017, ARM
>>>> + *
>>>> + * This program is free software; you can redistribute it and/or
>>>> modify it
>>>> + * under the terms and conditions of the GNU General Public License,
>>>> + * version 2, as published by the Free Software Foundation.
>>>> + *
>>>> + * This program is distributed in the hope it will be useful, but
>>>> WITHOUT
>>>> + * ANY WARRANTY; without even the implied warranty of
>>>> MERCHANTABILITY or
>>>> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
>>>> License for
>>>> + * more details.
>>>> + *
>>>> + * This file implements parsing of Processor Properties Topology
>>>> Table (PPTT)
>>>> + * which is optionally used to describe the processor and cache
>>>> topology.
>>>> + * Due to the relative pointers used throughout the table, this
>>>> doesn't
>>>> + * leverage the existing subtable parsing in the kernel.
>>>> + */
>>>> +#define pr_fmt(fmt) "ACPI PPTT: " fmt
>>>> +
>>>> +#include <linux/acpi.h>
>>>> +#include <linux/cacheinfo.h>
>>>> +#include <acpi/processor.h>
>>>> +
>>>> +/*
>>>> + * Given the PPTT table, find and verify that the subtable entry
>>>> + * is located within the table
>>>> + */
>>>> +static struct acpi_subtable_header *fetch_pptt_subtable(
>>>> + struct acpi_table_header *table_hdr, u32 pptt_ref)
>>>> +{
>>>> + struct acpi_subtable_header *entry;
>>>> +
>>>> + /* there isn't a subtable at reference 0 */
>>>> + if (!pptt_ref)
>>>> + return NULL;
>>>> +
>>>> + if (pptt_ref + sizeof(struct acpi_subtable_header) >
>>>> table_hdr->length)
>>>> + return NULL;
>>>> +
>>>> + entry = (struct acpi_subtable_header *)((u8 *)table_hdr +
>>>> pptt_ref);
>>>> +
>>>> + if (pptt_ref + entry->length > table_hdr->length)
>>>> + return NULL;
>>>> +
>>>> + return entry;
>>>> +}
>>>> +
>>>> +static struct acpi_pptt_processor *fetch_pptt_node(
>>>> + struct acpi_table_header *table_hdr, u32 pptt_ref)
>>>> +{
>>>> + return (struct acpi_pptt_processor
>>>> *)fetch_pptt_subtable(table_hdr, pptt_ref);
>>>> +}
>>>> +
>>>> +static struct acpi_pptt_cache *fetch_pptt_cache(
>>>> + struct acpi_table_header *table_hdr, u32 pptt_ref)
>>>> +{
>>>> + return (struct acpi_pptt_cache *)fetch_pptt_subtable(table_hdr,
>>>> pptt_ref);
>>>> +}
>>>> +
>>>> +static struct acpi_subtable_header *acpi_get_pptt_resource(
>>>> + struct acpi_table_header *table_hdr,
>>>> + struct acpi_pptt_processor *node, int resource)
>>>> +{
>>>> + u32 ref;
>>>> +
>>>> + if (resource >= node->number_of_priv_resources)
>>>> + return NULL;
>>>> +
>>>> + ref = *(u32 *)((u8 *)node + sizeof(struct acpi_pptt_processor) +
>>>> + sizeof(u32) * resource);
>>>> +
>>>> + return fetch_pptt_subtable(table_hdr, ref);
>>>> +}
>>>> +
>>>> +/*
>>>> + * given a pptt resource, verify that it is a cache node, then walk
>>>> + * down each level of caches, counting how many levels are found
>>>> + * as well as checking the cache type (icache, dcache, unified). If a
>>>> + * level & type match, then we set found, and continue the search.
>>>> + * Once the entire cache branch has been walked return its max
>>>> + * depth.
>>>> + */
>>>> +static int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
>>>> + int local_level,
>>>> + struct acpi_subtable_header *res,
>>>> + struct acpi_pptt_cache **found,
>>>> + int level, int type)
>>>> +{
>>>> + struct acpi_pptt_cache *cache;
>>>> +
>>>> + if (res->type != ACPI_PPTT_TYPE_CACHE)
>>>> + return 0;
>>>> +
>>>> + cache = (struct acpi_pptt_cache *) res;
>>>> + while (cache) {
>>>> + local_level++;
>>>> +
>>>> + if ((local_level == level) &&
>>>> + (cache->flags & ACPI_PPTT_CACHE_TYPE_VALID) &&
>>>> + ((cache->attributes & ACPI_PPTT_MASK_CACHE_TYPE) ==
>>>> type)) {
>>>
>>> Attributes have to be shifted:
>>>
>>> (cache->attributes & ACPI_PPTT_MASK_CACHE_TYPE) >> 2
>>
>> Hmmm, I'm not sure that is true, the top level function in this
>> routine convert the "linux" constant to the ACPI version of that
>> constant. In that case the "type" field is pre-shifted, so that it
>> matches the result of just anding against the field... That is unless
>> I messed something up, which I don't see at the moment (and the code
>> of course has been tested with PPTT's from multiple people at this
>> point).
>
> For ThunderX2 I got lots of errors in dmesg:
> Found duplicate cache level/type unable to determine uniqueness
>
> So I fixed "type" macros definitions (without shifting) and shift it
> here which fixes the issue. As you said, it can be pre-shifted as well.
>
>>
>>
>>>
>>>> + if (*found != NULL)
>>>> + pr_err("Found duplicate cache level/type unable to
>>>> determine uniqueness\n");
Actually I still see this error messages in my dmesg. It is because the
following ThunderX2 per-core L1 and L2 cache hierarchy:
Core
------------------
| |
| L1i ----- |
| | |
| ----L2 |
| | |
| L1d ----- |
| |
------------------
In this case we have two paths which lead to L2 cache and hit above
case. Is it really error case?
Thanks,
Tomasz
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