From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6898C481CD for ; Wed, 16 Jul 2025 16:21:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752682912; cv=none; b=WUqhvAcCjSi/e8fRvLGkd/aM0Us806HLl/vnJ7MwkG+rwvkT+lzMJeI+g+LYywUH2PIMYBJuRVZ5EAz8MOHs9Jo4pE/1inf2qYYoMzGB0k/74tqG1UBHCjJOzuYXzYHd1pLvae9l0SpTwNzJZtwEoEf1EIDWbqzbEdeWSCl/vTM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752682912; c=relaxed/simple; bh=M1oZgVTyYsLbNfFExN5SMkfDRrewPjlJvZlI2EMnlaU=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=tFBK5tyB959Y+El7RB9QMKVyTCsmt2gKZZghR2g5NYkqUVB3k4q4+wAPxLOqxBMNynmMFpRSxaenX7P07GoScDkWmJNdAzOApZytI2mPatphlCrbfNZdwT4Rlk6X+3cBTXb8zjZOeLUr9o3zj9BHF5lvb3lUDnpSjbn3OaDCXFc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.231]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4bj1W32DCTz6M4P9; Thu, 17 Jul 2025 00:20:31 +0800 (CST) Received: from frapeml500008.china.huawei.com (unknown [7.182.85.71]) by mail.maildlp.com (Postfix) with ESMTPS id EE67814038F; Thu, 17 Jul 2025 00:21:46 +0800 (CST) Received: from localhost (10.203.177.66) by frapeml500008.china.huawei.com (7.182.85.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Wed, 16 Jul 2025 18:21:45 +0200 Date: Wed, 16 Jul 2025 17:21:44 +0100 From: Jonathan Cameron To: James Morse CC: , , "Rob Herring" , Ben Horgan , Rohit Mathew , Shanker Donthineni , "Zeng Heng" , Lecopzer Chen , "Carl Worth" , , D Scott Phillips OS , , , , , Jamie Iles , Xin Hao , , , , David Hildenbrand , Rex Nie , Dave Martin , Koba Ko , Sudeep Holla Subject: Re: [RFC PATCH 07/36] ACPI / PPTT: Find cache level by cache-idUIRE Message-ID: <20250716172144.00000715@huawei.com> In-Reply-To: <20250711183648.30766-8-james.morse@arm.com> References: <20250711183648.30766-1-james.morse@arm.com> <20250711183648.30766-8-james.morse@arm.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: lhrpeml500004.china.huawei.com (7.191.163.9) To frapeml500008.china.huawei.com (7.182.85.71) On Fri, 11 Jul 2025 18:36:19 +0000 James Morse wrote: > The MPAM table identifies caches by id. The MPAM driver also wants to know > the cache level to determine if the platform is of the shape that can be > managed via resctrl. Cacheinfo has this information, but only for CPUs that > are online. > > Waiting for all CPUs to come online is a problem for platforms where > CPUs are brought online late by user-space. > > Add a helper that walks every possible cache, until it finds the one > identified by cache-id, then return the level. > > acpi_count_levels() expects its levels parameter to be initialised to > zero as it passes it to acpi_find_cache_level() as starting_level. > The existing callers do this. Document it. > > Signed-off-by: James Morse > Reviewed-by: Sudeep Holla A few suggestions inline. Mostly driven by the number of missing table puts I've seen in ACPI code. You don't have any missing here but with a bit of restructuring you can make that easy to see. > --- > drivers/acpi/pptt.c | 73 ++++++++++++++++++++++++++++++++++++++++++++ > include/linux/acpi.h | 5 +++ > 2 files changed, 78 insertions(+) > > diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c > index 13ca2eee3b98..f53748a5df19 100644 > --- a/drivers/acpi/pptt.c > +++ b/drivers/acpi/pptt.c > @@ -912,3 +912,76 @@ int find_acpi_cpu_topology_hetero_id(unsigned int cpu) > return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE, > ACPI_PPTT_ACPI_IDENTICAL); > } > + > +/** > + * find_acpi_cache_level_from_id() - Get the level of the specified cache > + * @cache_id: The id field of the unified cache > + * > + * Determine the level relative to any CPU for the unified cache identified by > + * cache_id. This allows the property to be found even if the CPUs are offline. > + * > + * The returned level can be used to group unified caches that are peers. > + * > + * The PPTT table must be rev 3 or later, > + * > + * If one CPUs L2 is shared with another as L3, this function will return > + * an unpredictable value. > + * > + * Return: -ENOENT if the PPTT doesn't exist, or the cache cannot be found. > + * Otherwise returns a value which represents the level of the specified cache. > + */ > +int find_acpi_cache_level_from_id(u32 cache_id) > +{ > + u32 acpi_cpu_id; > + acpi_status status; > + int level, cpu, num_levels; > + struct acpi_pptt_cache *cache; > + struct acpi_table_header *table; > + struct acpi_pptt_cache_v1 *cache_v1; > + struct acpi_pptt_processor *cpu_node; > + > + status = acpi_get_table(ACPI_SIG_PPTT, 0, &table); > + if (ACPI_FAILURE(status)) { > + acpi_pptt_warn_missing(); > + return -ENOENT; > + } > + > + if (table->revision < 3) { Maybe a unified exit path given all paths need to do acpi_put_table() and return either error or level. Or maybe it's time for some cleanup.h magic for acpi tables. I've been thinking about it for a while and mostly stuck on the name ;) (simpler suggestion follows) static struct acpi_table_header *acpi_get_table_ret(char *signature, u32 instance) { struct acpi_table_header *table; int status = acpi_get_table(signature, instance, &table); if (ACPI_FAILURE(status)) return ERR_PTR(-ENOENT); return table; } DEFINE_FREE(acpi_table, struct acpi_table_header *, if (!IS_ERR(_T)) acpi_put_table(_T)) Finally in here and loads of other places we avoid chance of missing an acpi_put_table and generally simplify the code a little. int find_acpi_cache_level_from_id(u32 cache_id) { u32 acpi_cpu_id; acpi_status status; int level, cpu, num_levels; struct acpi_pptt_cache *cache; struct acpi_pptt_cache_v1 *cache_v1; struct acpi_pptt_processor *cpu_node; struct acpi_table_header *table __free(acpi_table) = acpi_get_table_ret(ACPI_SIG_PPTT, 0); if (IS_ERR(table) return PTR_ERR(table); if (table->revision < 3) return -ENOENT; /* * If we found the cache first, we'd still need to walk from each CPU * to find the level... */ for_each_possible_cpu(cpu) { acpi_cpu_id = get_acpi_id_for_cpu(cpu); cpu_node = acpi_find_processor_node(table, acpi_cpu_id); if (!cpu_node) return -ENOENT; acpi_count_levels(table, cpu_node, &num_levels, NULL); /* Start at 1 for L1 */ for (level = 1; level <= num_levels; level++) { cache = acpi_find_cache_node(table, acpi_cpu_id, ACPI_PPTT_CACHE_TYPE_UNIFIED, level, &cpu_node); if (!cache) continue; cache_v1 = ACPI_ADD_PTR(struct acpi_pptt_cache_v1, cache, sizeof(struct acpi_pptt_cache)); if (cache->flags & ACPI_PPTT_CACHE_ID_VALID && cache_v1->cache_id == cache_id) { acpi_put_table(table); return level; } } } return -ENOENT; } A less 'fun' alternative is pull some code out as a helper to make put the get and put near each other with no conditionals to confuse things. static int __find_acpi_cache_level_from_id(u32 cache_id, struct acpi_table_header *head); { u32 acpi_cpu_id; int level, cpu, num_levels; struct acpi_pptt_cache *cache; struct acpi_pptt_cache_v1 *cache_v1; struct acpi_pptt_processor *cpu_node; if (table->revision < 3) return -ENOENT; /* * If we found the cache first, we'd still need to walk from each CPU * to find the level... */ for_each_possible_cpu(cpu) { acpi_cpu_id = get_acpi_id_for_cpu(cpu); cpu_node = acpi_find_processor_node(table, acpi_cpu_id); if (!cpu_node) return -ENOENT; acpi_count_levels(table, cpu_node, &num_levels, NULL); /* Start at 1 for L1 */ for (level = 1; level <= num_levels; level++) { cache = acpi_find_cache_node(table, acpi_cpu_id, ACPI_PPTT_CACHE_TYPE_UNIFIED, level, &cpu_node); if (!cache) continue; cache_v1 = ACPI_ADD_PTR(struct acpi_pptt_cache_v1, cache, sizeof(struct acpi_pptt_cache)); if (cache->flags & ACPI_PPTT_CACHE_ID_VALID && cache_v1->cache_id == cache_id) return level; } } return -ENOENT; } int find_acpi_cache_level_from_id(u32 cache_id) { int ret; acpi_status status; struct acpi_table_header *table; status = acpi_get_table(ACPI_SIG_PPTT, 0, &table); if (ACPI_FAILURE(status)) { acpi_pptt_warn_missing(); return -ENOENT; } ret = __find_acpi_cache_level_from_id(cache_id, table) acpi_put_table(table); return ret; } > + acpi_put_table(table); > + return -ENOENT; > + } > + > + /* > + * If we found the cache first, we'd still need to walk from each CPU > + * to find the level... > + */ > + for_each_possible_cpu(cpu) { > + acpi_cpu_id = get_acpi_id_for_cpu(cpu); > + cpu_node = acpi_find_processor_node(table, acpi_cpu_id); > + if (!cpu_node) > + break; > + acpi_count_levels(table, cpu_node, &num_levels, NULL); > + > + /* Start at 1 for L1 */ > + for (level = 1; level <= num_levels; level++) { > + cache = acpi_find_cache_node(table, acpi_cpu_id, > + ACPI_PPTT_CACHE_TYPE_UNIFIED, > + level, &cpu_node); > + if (!cache) > + continue; > + > + cache_v1 = ACPI_ADD_PTR(struct acpi_pptt_cache_v1, > + cache, > + sizeof(struct acpi_pptt_cache)); > + > + if (cache->flags & ACPI_PPTT_CACHE_ID_VALID && > + cache_v1->cache_id == cache_id) { > + acpi_put_table(table); > + return level; > + } > + } > + } > + > + acpi_put_table(table); > + return -ENOENT; > +} > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index 8c3165c2b083..82947f6d2a43 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -1542,6 +1542,7 @@ int find_acpi_cpu_topology_cluster(unsigned int cpu); > int find_acpi_cpu_topology_package(unsigned int cpu); > int find_acpi_cpu_topology_hetero_id(unsigned int cpu); > int acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id, cpumask_t *cpus); > +int find_acpi_cache_level_from_id(u32 cache_id); > #else > static inline int acpi_pptt_cpu_is_thread(unsigned int cpu) > { > @@ -1568,6 +1569,10 @@ static inline int acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id, > { > return -EINVAL; > } > +static inline int find_acpi_cache_level_from_id(u32 cache_id) > +{ > + return -EINVAL; > +} > #endif > > void acpi_arch_init(void);