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 9BCDF23C4F3; Fri, 19 Sep 2025 16:10:34 +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=1758298237; cv=none; b=lME7bk5gcJEdSb3sLKfQcdTnx6kdWJbSZEFSzKtC/m+17iMcreQrbIhHUYBsSI97U8vYWE/SdvqnsVpxE0k3fV4zFVZY5nXJHM6+G1364u6Kq7+XWJ22T9b9j3hGMRtFNYwNp14+SF2776f0dBCRTZhCMDB38eW3f1YDwF8A/I8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758298237; c=relaxed/simple; bh=sd6TB+nVjeIrvFsDkzOC+ASaFSRx3idy26nLorE2dPo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ik+4xdLn1qJiNrFxh+5/9en5YgnaLtL5AfcJMKRttu6yj5f0u75SGYa5ITRhBKY0N2NLL9o/f/2N5wTRuBp5S0z2YYhivcCwdFXwnW10b9yjfjCp32KmyRQ5unQg798y6ZK2RRuj6zDACBUO0bwQYTFqM6fysxwAC2eyKZFePHE= 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 5AE5E169C; Fri, 19 Sep 2025 09:10:24 -0700 (PDT) Received: from [10.1.197.69] (eglon.cambridge.arm.com [10.1.197.69]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 570503F66E; Fri, 19 Sep 2025 09:10:27 -0700 (PDT) Message-ID: <4f523696-54ab-427d-974a-3c5ffb865fed@arm.com> Date: Fri, 19 Sep 2025 17:10:25 +0100 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 v2 01/29] ACPI / PPTT: Add a helper to fill a cpumask from a processor container To: Jonathan Cameron Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, D Scott Phillips OS , carl@os.amperecomputing.com, lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao , peternewman@google.com, dfustini@baylibre.com, amitsinght@marvell.com, David Hildenbrand , Dave Martin , Koba Ko , Shanker Donthineni , fenghuay@nvidia.com, baisheng.gao@unisoc.com, Rob Herring , Rohit Mathew , Rafael Wysocki , Len Brown , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Catalin Marinas , Will Deacon , Greg Kroah-Hartman , Danilo Krummrich References: <20250910204309.20751-1-james.morse@arm.com> <20250910204309.20751-2-james.morse@arm.com> <20250911114337.0000487e@huawei.com> Content-Language: en-GB From: James Morse In-Reply-To: <20250911114337.0000487e@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Jonathan, On 11/09/2025 11:43, Jonathan Cameron wrote: > 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. >> 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. This is a strange one - you spotted it on your follow up email. >> + 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! Looks like that would have a knock on effect for the types in: | topology_get_acpi_cpu_tag() | acpi_find_processor_node() | cache_setup_acpi_cpu() | fetch_pptt_node() ... basically everywhere this file uses struct acpi_table_header... It's simpler to cast it here if you're keen on the '+1' approach, but this pattern is how this file does this. This is the same as acpi_pptt_leaf_node(). >> + proc_sz = sizeof(struct acpi_pptt_processor); > Maybe sizeof (*cpu_node) is more helpful to reader. (again, same as acpi_pptt_leaf_node()) > 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. I agree, but when in pptt.c ... > 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); It is the same - I think this is better as it reduces the scope of cpu_node. > 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() When this series had support for ACPI PPI-Partitions there were more PPTT helpers and I had a function pointer based call_on_every_entry() kind of thing. Jeremy L though it obscured the flow. A custom for_each_ is probably better. I may float it as an RFC after these are done. I don't want to make this series any bigger. It certainly makes the users easier on the eye. | drivers/acpi/pptt.c | 43 +++++++++++++++---------------------------- | 1 file changed, 15 insertions(+), 28 deletions(-) Stashed here for posterity: https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/commit/?h=pptt/for_each_pptt_entry/v0&id=353ceeba3d39c6b6a10eeb1a59c49649cdf719d8 > 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); >