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 DCE8ACA101F for ; Wed, 10 Sep 2025 19:18:30 +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=bJ5jRP4ekZSfa0FO7dY/jh+MX919UaUegXJ1S2jATo8=; b=HbDTICwivp1S5/Q+HPHchFqNBw ws6755g+Izq+pl/pOtnfE9Kkk512MSq46mO0UKqmkL6JcIkTfjk6eq6CkIGPhsthz1PrAnw11dTNl E918YbW4gAMRQ7BVf+Mi+0Cp09p7ORNoUB6EO4Fa0rp6MEPxgGKyOJSwhPWKxDTMk7I0jEJ+/L8LN LVF3G6KZC1SUtgNNai0yxzH2kXPbw5mqhhATzsyxc37p7GdigTeWhfymnjn0qITk4TU9D8wUHGrT/ 48Ow1CBXV75aMipiJvQ4pL+SSXZhs2h+WmbCwvbiqB0K51US2nuWQlScUp3q0msdZY4gfqYKBheFe E3iCHzsg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwQKg-0000000GDrw-1NWa; Wed, 10 Sep 2025 19:18:18 +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 1uwQKd-0000000GDqS-31DY for linux-arm-kernel@lists.infradead.org; Wed, 10 Sep 2025 19:18:17 +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 6233B16F2; Wed, 10 Sep 2025 12:18:04 -0700 (PDT) Received: from [10.1.197.69] (eglon.cambridge.arm.com [10.1.197.69]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D71143F694; Wed, 10 Sep 2025 12:18:06 -0700 (PDT) Message-ID: Date: Wed, 10 Sep 2025 20:18:04 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 06/33] ACPI / PPTT: Add a helper to fill a cpumask from a cache_id To: Lorenzo Pieralisi Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, devicetree@vger.kernel.org, shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , carl@os.amperecomputing.com, 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 , Shanker Donthineni , fenghuay@nvidia.com, baisheng.gao@unisoc.com, Jonathan Cameron , Rob Herring , Rohit Mathew , Rafael Wysocki , Len Brown , Hanjun Guo , Sudeep Holla , Krzysztof Kozlowski , Conor Dooley , Catalin Marinas , Will Deacon , Greg Kroah-Hartman , Danilo Krummrich References: <20250822153048.2287-1-james.morse@arm.com> <20250822153048.2287-41-james.morse@arm.com> Content-Language: en-GB From: James Morse In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250910_121815_857485_1BCE532A X-CRM114-Status: GOOD ( 24.19 ) 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 Lorenzo, On 10/09/2025 17:06, Lorenzo Pieralisi wrote: > On Fri, Aug 22, 2025 at 03:30:21PM +0000, James Morse wrote: >> MPAM identifies CPUs by the cache_id in the PPTT cache structure. >> >> The driver needs to know which CPUs are associated with the cache, >> the CPUs may not all be online, so cacheinfo does not have the >> information. >> >> Add a helper to pull this information out of the PPTT. >> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c >> index 660457644a5b..cb93a9a7f9b6 100644 >> --- a/drivers/acpi/pptt.c >> +++ b/drivers/acpi/pptt.c >> @@ -971,3 +971,65 @@ int find_acpi_cache_level_from_id(u32 cache_id) >> >> return -ENOENT; >> } >> + >> +/** >> + * acpi_pptt_get_cpumask_from_cache_id() - Get the cpus associated with the >> + * specified cache >> + * @cache_id: The id field of the unified cache >> + * @cpus: Where to build the cpumask >> + * >> + * Determine which CPUs are below this cache in the PPTT. This allows the property >> + * to be found even if the CPUs are offline. >> + * >> + * The PPTT table must be rev 3 or later, >> + * >> + * Return: -ENOENT if the PPTT doesn't exist, or the cache cannot be found. >> + * Otherwise returns 0 and sets the cpus in the provided cpumask. >> + */ >> +int acpi_pptt_get_cpumask_from_cache_id(u32 cache_id, cpumask_t *cpus) >> +{ >> + 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; >> + struct acpi_table_header *table __free(acpi_table) = acpi_get_table_ret(ACPI_SIG_PPTT, 0); >> + >> + cpumask_clear(cpus); >> + >> + if (IS_ERR(table)) >> + return -ENOENT; >> + >> + if (table->revision < 3) >> + return -ENOENT; >> + >> + /* >> + * If we found the cache first, we'd still need to walk from each cpu. >> + */ >> + 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 0; > > If for a possible cpu you don't get an acpi_pptt_processor node we return 0, > is that correct ? Should not the loop continue ? Forgive me if that's a > dumb question. That looks like me throwing my hands up in the air and bailing out! Yes, the loop continue-ing would be better as only possible CPUs that are missing a PPTT description (...and cache hierarchy...) would be missing form the bitmap. It's probably worth a WARN_ON_ONCE() too. Thanks for spotting that! >> + num_levels = acpi_count_levels(table, cpu_node, 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) >> + cpumask_set_cpu(cpu, cpus); >> + } >> + } >> + >> + return 0; >> +} >> diff --git a/include/linux/acpi.h b/include/linux/acpi.h >> index 30c10b1dcdb2..4ad08f5f1d83 100644 >> --- a/include/linux/acpi.h >> +++ b/include/linux/acpi.h >> @@ -1555,6 +1555,7 @@ int find_acpi_cpu_topology_package(unsigned int cpu); >> @@ -1582,6 +1583,11 @@ static inline int find_acpi_cache_level_from_id(u32 cache_id) >> { >> return -EINVAL; >> } >> +static inline int acpi_pptt_get_cpumask_from_cache_id(u32 cache_id, >> + cpumask_t *cpus) >> +{ >> + return -EINVAL; > > Nit: You might want the return value here to be coherent with what the function > documentation states (ie return -ENOENT;) Makes sense, > Other than that: > > Reviewed-by: Lorenzo Pieralisi Thanks! James