From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 26E7130F54E; Thu, 11 Sep 2025 10:43:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757587426; cv=none; b=EZwwlGlOvUNo8wNMrr9ExeeTWz22bIwFuVF37Kv7GdLgeZnuY2Zw8Sq+tfEwYYPcjp7V23uo/rC41zJXYlduLQEQ/Exe/tVrsfP8uR0jVGqA9p80Gnx9KrILtaCtcu4ZiNOmcpsPSgZvV/m7Aa98X1U0IYBKr3GdmXd8KfPGuR0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757587426; c=relaxed/simple; bh=4cjYNEq/0tkKAtFt1DgMEOaNIksXO5aYo797muokHU8=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=mksG5JozSiR32p+g8Ft7eLQ26D/RJYAIw8m17ebWyfJlXPxtjK4tvN88Ic9GA4rrHK5lcB04zLB2McQNckjIoy0vqn57/DIhb7FMRAmlXMr3yZzSH1f1ld/klznKOisen5sUb+agnjhY9R4nSi4VWO2b8MOT7mQfE1HhkI/pcrM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.31]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4cMvJc3Dk8z6L56v; Thu, 11 Sep 2025 18:42:24 +0800 (CST) Received: from frapeml500008.china.huawei.com (unknown [7.182.85.71]) by mail.maildlp.com (Postfix) with ESMTPS id 7BFCE1400D3; Thu, 11 Sep 2025 18:43:39 +0800 (CST) Received: from localhost (10.203.177.15) by frapeml500008.china.huawei.com (7.182.85.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Thu, 11 Sep 2025 12:43:38 +0200 Date: Thu, 11 Sep 2025 11:43:37 +0100 From: Jonathan Cameron To: James Morse CC: , , , D Scott Phillips OS , , , , , , Jamie Iles , Xin Hao , , , , David Hildenbrand , Dave Martin , Koba Ko , Shanker Donthineni , , , Rob Herring , Rohit Mathew , "Rafael Wysocki" , Len Brown , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Catalin Marinas , "Will Deacon" , Greg Kroah-Hartman , Danilo Krummrich Subject: Re: [PATCH v2 01/29] ACPI / PPTT: Add a helper to fill a cpumask from a processor container Message-ID: <20250911114337.0000487e@huawei.com> In-Reply-To: <20250910204309.20751-2-james.morse@arm.com> References: <20250910204309.20751-1-james.morse@arm.com> <20250910204309.20751-2-james.morse@arm.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: lhrpeml500011.china.huawei.com (7.191.174.215) To frapeml500008.china.huawei.com (7.182.85.71) On Wed, 10 Sep 2025 20:42:41 +0000 James Morse wrote: > 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 > Signed-off-by: James Morse Hi James, Sorry I missed v1. Busy few weeks. I think one resource leak plus a few suggested changes that I'm not that bothered about. Jonathan > --- > Changes since v1: > * Replaced commit message with wording from Dave. > * Fixed a stray plural. > * Moved further down in the file to make use of get_pptt() helper. > * Added a break to exit the loop early. > > Changes since RFC: > * Removed leaf_flag local variable from acpi_pptt_get_cpus_from_container() > > Changes since RFC: > * Dropped has_leaf_flag dodging of acpi_pptt_leaf_node() > * Added missing : in kernel-doc > * Made helper return void as this never actually returns an error. > --- > drivers/acpi/pptt.c | 83 ++++++++++++++++++++++++++++++++++++++++++++ > include/linux/acpi.h | 3 ++ > 2 files changed, 86 insertions(+) > > diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c > index 54676e3d82dd..1728545d90b2 100644 > --- a/drivers/acpi/pptt.c > +++ b/drivers/acpi/pptt.c > @@ -817,3 +817,86 @@ 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_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' 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. > + */ > +void 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; > + unsigned long table_end; > + u32 proc_sz; > + > + cpumask_clear(cpus); > + > + table_hdr = acpi_get_pptt(); This calls acpi_get_table() so you need to put it again or every call to this leaks a reference count. I messed around with DEFINE_FREE() for this but it doesn't fit that well as the underlying call doesn't return the table. This one does though so you could do a pptt specific one. Or just acpi_put_table(table_hdr); at exit path from this function. > + 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)); Hmm. Not related to this patch but I have no idea why acpi_get_pptt() doesn't return a struct acpi_table_pptt as if it did this would be a simple + 1 and not require those who only sometimes deal with ACPI code to go check what that macro actually does! > + proc_sz = sizeof(struct acpi_pptt_processor); Maybe sizeof (*cpu_node) is more helpful to reader. Also shorter so you could do while ((unsigned long)entry + sizeof(*cpu_node) <= table_end) > + while ((unsigned long)entry + proc_sz <= table_end) { > + cpu_node = (struct acpi_pptt_processor *)entry; For me, assigning this before checking the type is inelegant. but the nesting does get deep without it so I guess this is ok maybe, though I wonder if better reorganized to combine a different bunch of conditions. I think this is functionally identival. if (entry->type == ACPI_PTT_TYPE_PROCESSOR) { struct acpi_pptt_processor *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); More generally I wonder if it is worth adding a for_each_acpi_pptt_entry() macro. There is some precedence in drivers acpi such as for_each_nhlt_endpoint() That's probably material for another day though unless you think it brings enough benefits to do it here. > + if (entry->type == ACPI_PPTT_TYPE_PROCESSOR && > + cpu_node->flags & ACPI_PPTT_ACPI_PROCESSOR_ID_VALID) { > + if (!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); > + 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 1c5bb1e887cd..f97a9ff678cc 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);