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 EDF122E719B; Wed, 19 Nov 2025 10:00:41 +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=1763546444; cv=none; b=A7mhOEx/zaTdokMzYvuxlNeb5tya8I5Q7A6w6RE7nUO9Nv7nj1CqqQof6hV0VMWFl3FAeI2fOFTgY80HXNLAygZ0H7rxi2iYaTJHLlZ2I1fJeQnz50SvohhyowzoIo7wmpI68qu9pKEpqAWv8szWeEuFtBFS9c5twns64NDOvRs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763546444; c=relaxed/simple; bh=kkzJQHrqOrhQammoetUn6ZUlAXD70+ipvtJBIpExG80=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=b6MRHGOGDbQk2vx1OM/dA8CoT/Mvg+Od2AW5vWXAFbdZj33vmCYJj/Ae13wQvWwq/X4HgIfY6sKPLxIIFdN5usEAWI5MEndF4YsjV9YYoZW4AZsT+higIiZD35yHCxCQlLrBLmZB7ZRv+wDSncFi5FtVQJON3Ct0iu3QMtmrsuI= 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 76950FEC; Wed, 19 Nov 2025 02:00:33 -0800 (PST) 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 336103F740; Wed, 19 Nov 2025 02:00:36 -0800 (PST) Message-ID: <6eaf7e9c-a833-44c8-a213-7247a47d417d@arm.com> Date: Wed, 19 Nov 2025 10:00:34 +0000 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: [PATCH v5 01/34] ACPI / PPTT: Add a helper to fill a cpumask from a processor container To: Gavin Shan , james.morse@arm.com Cc: amitsinght@marvell.com, baisheng.gao@unisoc.com, baolin.wang@linux.alibaba.com, bobo.shaobowang@huawei.com, carl@os.amperecomputing.com, catalin.marinas@arm.com, dakr@kernel.org, dave.martin@arm.com, david@redhat.com, dfustini@baylibre.com, fenghuay@nvidia.com, gregkh@linuxfoundation.org, guohanjun@huawei.com, jeremy.linton@arm.com, jonathan.cameron@huawei.com, kobak@nvidia.com, lcherian@marvell.com, lenb@kernel.org, linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, lpieralisi@kernel.org, peternewman@google.com, quic_jiles@quicinc.com, rafael@kernel.org, robh@kernel.org, rohit.mathew@arm.com, scott@os.amperecomputing.com, sdonthineni@nvidia.com, sudeep.holla@arm.com, tan.shaopeng@fujitsu.com, will@kernel.org, xhao@linux.alibaba.com, Shaopeng Tan , Zeng Heng References: <20251117170014.4113754-1-ben.horgan@arm.com> <20251117170014.4113754-2-ben.horgan@arm.com> <455c577a-2c6b-4d57-9547-8f55bfe1c126@redhat.com> From: Ben Horgan Content-Language: en-US In-Reply-To: <455c577a-2c6b-4d57-9547-8f55bfe1c126@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Gavin, On 11/19/25 03:35, Gavin Shan wrote: > Hi Ben, > > On 11/18/25 2:59 AM, Ben Horgan wrote: >> From: James Morse >> >> The ACPI MPAM table uses the UID of a processor container specified in >> the PPTT to indicate the subset of CPUs and cache topology that can >> access each MPAM System Component (MSC). >> >> This information is not directly useful to the kernel. The equivalent >> cpumask is needed instead. >> >> 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. >> >> CC: Dave Martin >> Reviewed-by: Sudeep Holla >> Reviewed-by: Jonathan Cameron >> Reviewed-by: Fenghua Yu >> Reviewed-by: Gavin Shan >> Reviewed-by: Shaopeng Tan >> Tested-by: Fenghua Yu >> Tested-by: Shaopeng Tan >> Tested-by: Peter Newman >> Tested-by: Carl Worth >> Tested-by: Gavin Shan >> Tested-by: Zeng Heng >> Signed-off-by: James Morse >> Signed-off-by: Ben Horgan >> --- >> Changes since v4: >> Remove blank line >> >> Changes since v3: >> Refer to processor hierarchy in comments (Jonathan) >> Fix indent (Jonathan) >> --- >>   drivers/acpi/pptt.c  | 84 ++++++++++++++++++++++++++++++++++++++++++++ >>   include/linux/acpi.h |  3 ++ >>   2 files changed, 87 insertions(+) >> > > Since this series may need another respin, a nitpick below... > >> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c >> index 54676e3d82dd..b8248c0092fe 100644 >> --- a/drivers/acpi/pptt.c >> +++ b/drivers/acpi/pptt.c >> @@ -817,3 +817,87 @@ int find_acpi_cpu_topology_hetero_id(unsigned int >> cpu) >>       return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE, >>                         ACPI_PPTT_ACPI_IDENTICAL); >>   } >> + >> +/** >> + * acpi_pptt_get_child_cpus() - Find all the CPUs below a PPTT >> + * processor hierarchy node >> + * >> + * @table_hdr:        A reference to the PPTT table >> + * @parent_node:    A pointer to the processor hierarchy node in the >> + *            table_hdr >> + * @cpus:        A cpumask to fill with the CPUs below @parent_node >> + * >> + * Walks up the PPTT from every possible CPU to find if the provided >> + * @parent_node is a parent of this CPU. >> + */ >> +static void acpi_pptt_get_child_cpus(struct acpi_table_header >> *table_hdr, >> +                     struct acpi_pptt_processor *parent_node, >> +                     cpumask_t *cpus) >> +{ >> +    struct acpi_pptt_processor *cpu_node; >> +    u32 acpi_id; >> +    int cpu; >> + >> +    cpumask_clear(cpus); >> + > > The CPU mask has been cleared in its only caller > acpi_pptt_get_cpus_from_container(), > no need to clear it again. I'd rather not change this as it adds extra constraints on the caller which aren't necessarily expected. > >> +    for_each_possible_cpu(cpu) { >> +        acpi_id = get_acpi_id_for_cpu(cpu); >> +        cpu_node = acpi_find_processor_node(table_hdr, acpi_id); >> + >> +        while (cpu_node) { >> +            if (cpu_node == parent_node) { >> +                cpumask_set_cpu(cpu, cpus); >> +                break; >> +            } >> +            cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent); >> +        } >> +    } >> +} >> + >> +/** >> + * acpi_pptt_get_cpus_from_container() - Populate a cpumask with all >> CPUs in a >> + *                                       processor container >> + * @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 Hierarchy' 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. >> + */ >> +void acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id, cpumask_t *cpus) >> +{ >> +    struct acpi_table_header *table_hdr; >> +    struct acpi_subtable_header *entry; >> +    unsigned long table_end; >> +    u32 proc_sz; >> + >> +    cpumask_clear(cpus); >> + >> +    table_hdr = acpi_get_pptt(); >> +    if (!table_hdr) >> +        return; >> + >> +    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) { >> +        if (entry->type == ACPI_PPTT_TYPE_PROCESSOR) { >> +            struct acpi_pptt_processor *cpu_node; >> + >> +            cpu_node = (struct acpi_pptt_processor *)entry; >> +            if (cpu_node->flags & ACPI_PPTT_ACPI_PROCESSOR_ID_VALID && >> +                !acpi_pptt_leaf_node(table_hdr, cpu_node) && >> +                cpu_node->acpi_processor_id == acpi_cpu_id) { >> +                acpi_pptt_get_child_cpus(table_hdr, cpu_node, cpus); >> +                break; >> +            } >> +        } >> +        entry = ACPI_ADD_PTR(struct acpi_subtable_header, entry, >> +                     entry->length); >> +    } >> +} >> diff --git a/include/linux/acpi.h b/include/linux/acpi.h >> index 5ff5d99f6ead..4752ebd48132 100644 >> --- a/include/linux/acpi.h >> +++ b/include/linux/acpi.h >> @@ -1541,6 +1541,7 @@ int find_acpi_cpu_topology(unsigned int cpu, int >> level); >>   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); >> +void acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id, cpumask_t >> *cpus); >>   #else >>   static inline int acpi_pptt_cpu_is_thread(unsigned int cpu) >>   { >> @@ -1562,6 +1563,8 @@ static inline int >> find_acpi_cpu_topology_hetero_id(unsigned int cpu) >>   { >>       return -EINVAL; >>   } >> +static inline void acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id, >> +                             cpumask_t *cpus) { } >>   #endif >>     void acpi_arch_init(void); > > Thanks, > Gavin > Thanks, Ben