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 0EAB2364024; Wed, 19 Nov 2025 16:22:47 +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=1763569372; cv=none; b=sr9ObgmKGHW3VuY93IGUL5c7lj43VNswEaLT5CZ0HN0yMgGhO4wSzKNziuzXCVXTcB5a1BFStStf7cn25WvsyT8T13MTiqTpU+tYCZVJ4Q217fR30MBDkJPuaU3L+fTEBYfhaVVcSxHdff54lTA1BD1c4DMqXd41vqqoCa15Yuo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763569372; c=relaxed/simple; bh=DGV5WBl4QL57tpSmhP4tE+1N0eNg+kRyrs/MSgyTJxE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=nygH4qbJoj/tyS89wvth8QD5Q1VWR6yWDXFHLN7uETU5GdST10zulLrJ5fTUNLTIgJ9hcnae+FuKw53zGWFHEv12JhKNMMRPj2uEWwk0+n2os6kIqUy+MssVD6muTsU9n/Vk7etU1yFT90MfwvyQxj/AKKt4mQfZ6dcfeA8SCy0= 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 B7802FEC; Wed, 19 Nov 2025 08:22:39 -0800 (PST) Received: from [172.27.42.169] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A05953F740; Wed, 19 Nov 2025 08:22:43 -0800 (PST) Message-ID: Date: Wed, 19 Nov 2025 10:22:42 -0600 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: Ben Horgan , 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, gshan@redhat.com, guohanjun@huawei.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> Content-Language: en-US From: Jeremy Linton In-Reply-To: <20251117170014.4113754-2-ben.horgan@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/17/25 10:59 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. Reviewed-by: Jeremy Linton > > 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(+) > > 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); > + > + 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);