From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D7692CAC587 for ; Thu, 11 Sep 2025 15:27:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=HnVUiSS683V0TYoIS7/N9EvcUMjg74t7wLDaJj3T1qM=; b=mPAgkxAhe7VBQluHy3MeHcs6BH n1xHo/KoykloZqQi03baGL2t8gzBBE42d+UfGP8nB2Y66ekLVjW3asjAM6K9PMqEys+tEurZuBE43 qpqw4hKn4HfC3er+r0zBowtEIuHnnM8g5/HLy5Iaqf/8coqPCZz0uFgSnWlMud3A4DZIlJoKOI4hv A8rLnphKMECX+H6Wfobhi7CoZGqLZ2DCuURqQTxdwnW73Tl36iv38eHP7XCFq30DIgm2yc+QRk2nr VVhQgLM4kLoOl7fWOKVPGMzL1hbSuvEDl6Z/Hbl8RdtcZcG3nLlDPiq9QOUpt8d/Jhz3RQqTYHXtd Jvb+GFDw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwjCo-00000003sce-2zU8; Thu, 11 Sep 2025 15:27:26 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwjCm-00000003saz-41Fk for linux-arm-kernel@lists.infradead.org; Thu, 11 Sep 2025 15:27:25 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 617A2601B3; Thu, 11 Sep 2025 15:27:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 636D8C4CEF0; Thu, 11 Sep 2025 15:27:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757604444; bh=D3N+Ef/rke9QWrb1MoCvscwdGllgA6s5GKc7E8KKB3w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YE3RHdmVcPlTSLUiknlySzD6Op20ejQ4WJXsNd7CO6lEOWWSZq+rQIVhSKo4S9ctX IdHrlgIrjs6zJlPOObObXjCT2hdgZL5PuPFBJwq8IomHnY+1XprlZ/tbeA0BAOmstP 4TRXIHwPZjauYgX/VuZNH/RXVy24xZYOIRwYhAW6QQfratDCqH8/PONWHBTQCmh7kE u1OB1VCksyinkaJMOx79rIw6pInh5+aEpOuRupxDxZWRfIUC6KIRVPzQfvSCdiNTCo yBJlKfbWGFPdvWeMCO00pjcri9bBWzXGZWAdR8VNHXhkE7pMt9jfyJp4K1mF5Gig9k f7GSK6pQfvL2Q== Date: Thu, 11 Sep 2025 17:27:12 +0200 From: Lorenzo Pieralisi To: James Morse 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, Jonathan Cameron , Rob Herring , Rohit Mathew , Rafael Wysocki , Len Brown , Hanjun Guo , Sudeep Holla , Catalin Marinas , Will Deacon , Greg Kroah-Hartman , Danilo Krummrich Subject: Re: [PATCH v2 03/29] ACPI / PPTT: Find cache level by cache-id Message-ID: References: <20250910204309.20751-1-james.morse@arm.com> <20250910204309.20751-4-james.morse@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250910204309.20751-4-james.morse@arm.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Sep 10, 2025 at 08:42:43PM +0000, James Morse wrote: > The MPAM table identifies caches by id. The MPAM driver also wants to know > the cache level to determine if the platform is of the shape that can be > managed via resctrl. Cacheinfo has this information, but only for CPUs that > are online. > > Waiting for all CPUs to come online is a problem for platforms where > CPUs are brought online late by user-space. > > Add a helper that walks every possible cache, until it finds the one > identified by cache-id, then return the level. > > Signed-off-by: James Morse > --- > Changes since v1: > * Droppeed the cleanup based table freeing, use acpi_get_pptt() instead. > * Removed a confusing comment. > * Clarified the kernel doc. > > Changes since RFC: > * acpi_count_levels() now returns a value. > * Converted the table-get stuff to use Jonathan's cleanup helper. > * Dropped Sudeep's Review tag due to the cleanup change. > --- > drivers/acpi/pptt.c | 62 ++++++++++++++++++++++++++++++++++++++++++++ > include/linux/acpi.h | 5 ++++ > 2 files changed, 67 insertions(+) > > diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c > index 7af7d62597df..c5f2a51d280b 100644 > --- a/drivers/acpi/pptt.c > +++ b/drivers/acpi/pptt.c > @@ -904,3 +904,65 @@ void acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id, cpumask_t *cpus) > entry->length); > } > } > + > +/* > + * find_acpi_cache_level_from_id() - Get the level of the specified cache > + * @cache_id: The id field of the unified cache > + * > + * Determine the level relative to any CPU for the unified cache identified by > + * cache_id. This allows the property to be found even if the CPUs are offline. > + * > + * The returned level can be used to group unified caches that are peers. > + * > + * The PPTT table must be rev 3 or later, * The PPTT table must be rev 3 or later. > + * > + * If one CPUs L2 is shared with another as L3, this function will return > + * an unpredictable value. > + * > + * Return: -ENOENT if the PPTT doesn't exist, the revision isn't supported or > + * the cache cannot be found. > + * Otherwise returns a value which represents the level of the specified cache. > + */ > +int find_acpi_cache_level_from_id(u32 cache_id) > +{ > + u32 acpi_cpu_id; > + int level, cpu, num_levels; > + struct acpi_pptt_cache *cache; > + struct acpi_table_header *table; > + struct acpi_pptt_cache_v1 *cache_v1; > + struct acpi_pptt_processor *cpu_node; > + > + table = acpi_get_pptt(); > + if (!table) > + return -ENOENT; > + > + if (table->revision < 3) > + return -ENOENT; > + > + for_each_possible_cpu(cpu) { > + acpi_cpu_id = get_acpi_id_for_cpu(cpu); > + cpu_node = acpi_find_processor_node(table, acpi_cpu_id); > + if (!cpu_node) > + return -ENOENT; Same comment as in another patch - don't think you want to stop parsing here. > + num_levels = acpi_count_levels(table, cpu_node, NULL); > + > + /* Start at 1 for L1 */ > + for (level = 1; level <= num_levels; level++) { > + cache = acpi_find_cache_node(table, acpi_cpu_id, > + ACPI_PPTT_CACHE_TYPE_UNIFIED, > + level, &cpu_node); > + if (!cache) > + continue; > + > + cache_v1 = ACPI_ADD_PTR(struct acpi_pptt_cache_v1, > + cache, > + sizeof(struct acpi_pptt_cache)); > + > + if (cache->flags & ACPI_PPTT_CACHE_ID_VALID && > + cache_v1->cache_id == cache_id) > + return level; > + } > + } > + > + return -ENOENT; > +} > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index f97a9ff678cc..5bdca5546697 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -1542,6 +1542,7 @@ 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); > +int find_acpi_cache_level_from_id(u32 cache_id); > #else > static inline int acpi_pptt_cpu_is_thread(unsigned int cpu) > { > @@ -1565,6 +1566,10 @@ static inline int find_acpi_cpu_topology_hetero_id(unsigned int cpu) > } > static inline void acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id, > cpumask_t *cpus) { } > +static inline int find_acpi_cache_level_from_id(u32 cache_id) > +{ > + return -EINVAL; return -ENOENT; Reviewed-by: Lorenzo Pieralisi > +} > #endif > > void acpi_arch_init(void); > -- > 2.39.5 >