| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <46e3ead8-411d-4e51-b38b-da791e568b94@arm.com>
Date: Wed, 23 Jul 2025 15:42:52 +0100
From: Ben Horgan <ben.horgan@....com>
To: James Morse <james.morse@....com>, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Cc: Rob Herring <robh@...nel.org>, Rohit Mathew <rohit.mathew@....com>,
Shanker Donthineni <sdonthineni@...dia.com>, Zeng Heng
<zengheng4@...wei.com>, Lecopzer Chen <lecopzerc@...dia.com>,
Carl Worth <carl@...amperecomputing.com>,
shameerali.kolothum.thodi@...wei.com,
D Scott Phillips OS <scott@...amperecomputing.com>, lcherian@...vell.com,
bobo.shaobowang@...wei.com, tan.shaopeng@...itsu.com,
baolin.wang@...ux.alibaba.com, Jamie Iles <quic_jiles@...cinc.com>,
Xin Hao <xhao@...ux.alibaba.com>, peternewman@...gle.com,
dfustini@...libre.com, amitsinght@...vell.com,
David Hildenbrand <david@...hat.com>, Rex Nie <rex.nie@...uarmicro.com>,
Dave Martin <dave.martin@....com>, Koba Ko <kobak@...dia.com>,
Sudeep Holla <sudeep.holla@....com>
Subject: Re: [RFC PATCH 05/36] ACPI / PPTT: Add a helper to fill a cpumask
from a processor container
Hi James,
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.
>
> CC: Dave Martin <dave.martin@....com>
> Reviewed-by: Sudeep Holla <sudeep.holla@....com>
> Signed-off-by: James Morse <james.morse@....com>
> ---
> drivers/acpi/pptt.c | 93 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/acpi.h | 6 +++
> 2 files changed, 99 insertions(+)
>
> 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_table_he
> return NULL;
> }
>
> +/**
> + * acpi_pptt_get_child_cpus() - Find all the CPUs below a PPTT processor node
> + * @table_hdr: A reference to the PPTT table.
> + * @parent_node: A pointer to the processor 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 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.
> + }
> + entry = ACPI_ADD_PTR(struct acpi_subtable_header, entry,
> + entry->length);
> + }
> +
> + acpi_put_table(table_hdr);
> +
> + return ret;
> +}
> +
> static u8 acpi_cache_type(enum cache_type type)
> {
> switch (type) {
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index f102c0fe3431..8c3165c2b083 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);
> +int 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 +1563,11 @@ static inline int find_acpi_cpu_topology_hetero_id(unsigned int cpu)
> {
> return -EINVAL;
> }
> +static inline int acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id,
> + cpumask_t *cpus)
> +{
> + return -EINVAL;
> +}
> #endif
>
> void acpi_arch_init(void);
Thanks,
Ben
Powered by blists - more mailing lists