From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 040FFC83F1B for ; Mon, 14 Jul 2025 11:52:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=/wNvbyIq/akFxDtsdGlKUkxzIZgm3Lgtt8RbIXfXfp0=; b=VI4chEGmWXis4GVnTIBnQZ0VlJ n5h1dZ2KOYz4fZqxciKpUvNAJ2N0bhS/LDA9eZznZiYONmdg1WVa81VniRuWDmO6tG1ZuuvkuC0f3 /iBNN1icbnaufsMwMsZ+/rCvLfADklLBqUuR0tr1MGRGyxJkvomqnncrTZaPuegpNno1J5bWFecMB D2x4KBNM18X6WxC6HvpS56pxQU6vEsBUaxwC68pMEiQIRAspgtEO6a/fmWhA8VhyC4thPRC81dfO5 5dhslPSzlWkMh1sCfRP1CKz45YZ45qjX8BecN6/nxlfgC/+GoQ1WAoe7t75/ei5Il32gX8mLpnv+k Q32hsB7w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1ubHjj-000000024V7-1NfA; Mon, 14 Jul 2025 11:52:47 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1ubHa0-0000000237i-2T76 for linux-arm-kernel@lists.infradead.org; Mon, 14 Jul 2025 11:42:45 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8BCBA1D70; Mon, 14 Jul 2025 04:42:34 -0700 (PDT) Received: from [10.1.196.46] (e134344.arm.com [10.1.196.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7A2E63F694; Mon, 14 Jul 2025 04:42:40 -0700 (PDT) Message-ID: Date: Mon, 14 Jul 2025 12:42:39 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 07/36] ACPI / PPTT: Find cache level by cache-id To: James Morse , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Rob Herring , Rohit Mathew , Shanker Donthineni , Zeng Heng , Lecopzer Chen , Carl Worth , shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao , peternewman@google.com, dfustini@baylibre.com, amitsinght@marvell.com, David Hildenbrand , Rex Nie , Dave Martin , Koba Ko , Sudeep Holla References: <20250711183648.30766-1-james.morse@arm.com> <20250711183648.30766-8-james.morse@arm.com> Content-Language: en-US From: Ben Horgan In-Reply-To: <20250711183648.30766-8-james.morse@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250714_044244_722113_0B8F7441 X-CRM114-Status: GOOD ( 28.78 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi James, On 7/11/25 19:36, 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. This paragraph is stale. You dealt with this in the previous commit. > > Signed-off-by: James Morse > Reviewed-by: Sudeep Holla > --- > 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) { > + 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); Thanks, Ben