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 BE6D2280025; Wed, 12 Nov 2025 10:14:11 +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=1762942454; cv=none; b=Oj4ZK/8IiNQyXX/8MHbszy0vLZiyJ8+yfK7Kv3MJxJWB33R8puU1m+EDj54A/XMFhY/OXMd8XZ7WM4bX4h9UqR5IOYDnnhyrGy2NnM6L6N9OYpj9Q8Z6f7E65OQMcg6YQbiHlmaBfDsZHjkJ8RmiPvY0nEAwgsZk5vumP3UoJUU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762942454; c=relaxed/simple; bh=OhqdizDqUMSv1sLBX1ZxZKWQ0KFBOMmKlbnG45xQFpg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=u740aD3Zs72jwsaDBdxIgI9yadDkSosdnuNMpgU+UZCuGMyDgWfckdHZhX2MJZzLp7JG6yREUuZzAvmF960Ip8oOrea2yBh1glX0EvudIfhjNnz/+KjFE4vvbG/OBb8O5SbdzqGBCuqpq0WYauLRHtzq2+znKg7yErfkX4u4MEM= 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 10E9C1515; Wed, 12 Nov 2025 02:14:03 -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 0C5DC3F5A1; Wed, 12 Nov 2025 02:14:05 -0800 (PST) Message-ID: Date: Wed, 12 Nov 2025 10:14:04 +0000 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 01/33] 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 References: <20251107123450.664001-1-ben.horgan@arm.com> <20251107123450.664001-2-ben.horgan@arm.com> <11f80800-2e0b-4f41-a022-a88ad9792da8@redhat.com> From: Ben Horgan Content-Language: en-US In-Reply-To: <11f80800-2e0b-4f41-a022-a88ad9792da8@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Gavin, On 11/8/25 04:31, Gavin Shan wrote: > Hi Ben, > > On 11/7/25 10:34 PM, 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 >> Tested-by: Fenghua Yu >> Tested-by: Shaopeng Tan >> Tested-by: Peter Newman >> Signed-off-by: James Morse >> Signed-off-by: Ben Horgan >> --- >> Changes since v3: >> Refer to processor hierarchy in comments (Jonathan) >> Fix indent (Jonathan) >> --- >>   drivers/acpi/pptt.c  | 85 ++++++++++++++++++++++++++++++++++++++++++++ >>   include/linux/acpi.h |  3 ++ >>   2 files changed, 88 insertions(+) >> > > Two nitpicks below... > >> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c >> index 54676e3d82dd..69917cc6bd2f 100644 >> --- a/drivers/acpi/pptt.c >> +++ b/drivers/acpi/pptt.c >> @@ -817,3 +817,88 @@ 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); >> + >> +    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) { >> + > > Unnecessary blank line here. Ack > >> +        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); > > Need we to check if @cpu_node does crosses the boundary (@table_end), as > what's > doing in acpi_find_processor_node()? Actually, the similar hunk of code > from > the function can be reused here. As acpi_find_processor_node() is called from acpi_pptt_get_child_cpus() I don't think we need to duplicate the checking here. > > static struct acpi_pptt_processor *acpi_find_processor_node(struct > acpi_table_header *table_hdr, >                                                             u32 > acpi_cpu_id) > { >         : >     while ((unsigned long)entry + proc_sz <= table_end) { >                 cpu_node = (struct acpi_pptt_processor *)entry; > >                 if (entry->length == 0) { >                         pr_warn("Invalid zero length subtable\n"); >                         break; >                 } > >                 /* entry->length may not equal proc_sz, revalidate the > processor structure length */ >                 if (entry->type == ACPI_PPTT_TYPE_PROCESSOR && >                     acpi_cpu_id == cpu_node->acpi_processor_id && >                     (unsigned long)entry + entry->length <= table_end && >                     entry->length == proc_sz + cpu_node- >>number_of_priv_resources * sizeof(u32) && >                      acpi_pptt_leaf_node(table_hdr, cpu_node)) { >                         return (struct acpi_pptt_processor *)entry; >                 } > >                 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