From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CEB042882DC for ; Fri, 25 Jul 2025 17:05:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753463159; cv=none; b=SH1Zk5rL0yj7/W2CHyI0euOR1+hTS/eWZ1jlud4OacpegDaALH+PAQLQmlz591TU4KnaHFb9U32MFBIdWVrrapgCRUWrW/6PG9+ivwqYCL5G8Wkax3FlC/UVM03GCpThKDHy4LOA+02vZvoEuZRBhZLv18FjnzkMVs07gNqsaL8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753463159; c=relaxed/simple; bh=7d/+iASQMybHR/tMX/RIRDRqSIKIWpUdei5sXq19BN0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=rcIOd+MraEpWKF+w5+J7jkk4SgzdeinxngEsBc0ZylNEH+r/iTQ3gPUkVJsCw63o1eZp6qnCT0Lo+wcjzMEdNwO5EODaGAJJiQzq19R2X9zHvShL3qz6QvpXv8Ai38AACPyng07CVAJOG5U6xlMuDWcQS6x+CcsXOGrU+35YfBs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 CD78C176C; Fri, 25 Jul 2025 10:05:48 -0700 (PDT) Received: from [10.1.197.43] (eglon.cambridge.arm.com [10.1.197.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A4E763F66E; Fri, 25 Jul 2025 10:05:51 -0700 (PDT) Message-ID: <3fe6b4a6-d27b-4530-9f76-eb6c0daabbde@arm.com> Date: Fri, 25 Jul 2025 18:05:48 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 05/36] ACPI / PPTT: Add a helper to fill a cpumask from a processor container To: Ben Horgan , 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> <20250711183648.30766-6-james.morse@arm.com> <46e3ead8-411d-4e51-b38b-da791e568b94@arm.com> Content-Language: en-GB From: James Morse In-Reply-To: <46e3ead8-411d-4e51-b38b-da791e568b94@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Ben, On 23/07/2025 15:42, Ben Horgan wrote: > On 7/11/25 19:36, James Morse wrote: >> The PPTT describes CPUs and caches, as well as processor containers. >> The ACPI table for MPAM describes the set of CPUs that can access an MSC >> with the UID of a processor container. >> >> Add a helper to find the processor container by its id, then walk >> the possible CPUs to fill a cpumask with the CPUs that have this >> processor container as a parent. >> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c >> index 54676e3d82dd..13619b1b821b 100644 >> --- a/drivers/acpi/pptt.c >> +++ b/drivers/acpi/pptt.c >> @@ -298,6 +298,99 @@ static struct acpi_pptt_processor *acpi_find_processor_node(struct >> +/** >> + * acpi_pptt_get_cpus_from_container() - Populate a cpumask with all CPUs in a >> + *                                       processor containers >> + * @acpi_cpu_id:    The UID of the processor container. >> + * @cpus        The resulting CPU mask. >> + * >> + * Find the specified Processor Container, and fill @cpus with all the cpus >> + * below it. >> + * >> + * Not all 'Processor' entries in the PPTT are either a CPU or a Processor >> + * Container, they may exist purely to describe a Private resource. CPUs >> + * have to be leaves, so a Processor Container is a non-leaf that has the >> + * 'ACPI Processor ID valid' flag set. >> + * >> + * Return: 0 for a complete walk, or an error if the mask is incomplete. >> + */ >> +int acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id, cpumask_t *cpus) >> +{ >> +    struct acpi_pptt_processor *cpu_node; >> +    struct acpi_table_header *table_hdr; >> +    struct acpi_subtable_header *entry; >> +    bool leaf_flag, has_leaf_flag = false; >> +    unsigned long table_end; >> +    acpi_status status; >> +    u32 proc_sz; >> +    int ret = 0; >> + >> +    cpumask_clear(cpus); >> + >> +    status = acpi_get_table(ACPI_SIG_PPTT, 0, &table_hdr); >> +    if (ACPI_FAILURE(status)) >> +        return 0; >> + >> +    if (table_hdr->revision > 1) >> +        has_leaf_flag = true; >> + >> +    table_end = (unsigned long)table_hdr + table_hdr->length; >> +    entry = ACPI_ADD_PTR(struct acpi_subtable_header, table_hdr, >> +                 sizeof(struct acpi_table_pptt)); >> +    proc_sz = sizeof(struct acpi_pptt_processor); >> +    while ((unsigned long)entry + proc_sz <= table_end) { >> +        cpu_node = (struct acpi_pptt_processor *)entry; >> +        if (entry->type == ACPI_PPTT_TYPE_PROCESSOR && >> +            cpu_node->flags & ACPI_PPTT_ACPI_PROCESSOR_ID_VALID) { >> +            leaf_flag = cpu_node->flags & ACPI_PPTT_ACPI_LEAF_NODE; >> +            if ((has_leaf_flag && !leaf_flag) || >> +                (!has_leaf_flag && !acpi_pptt_leaf_node(table_hdr, cpu_node))) { >> +                if (cpu_node->acpi_processor_id == acpi_cpu_id) >> +                    acpi_pptt_get_child_cpus(table_hdr, cpu_node, cpus); >> +            } > acpi_pptt_leaf_node() returns early based on the leaf flag so you can just rely on that > here; remove has_leaf_flag and the corresponding extra logic. Aha! I was only doing this to try and avoid that extra descent of the tree. I missed that its already taken into account. Thanks, James