From nobody Tue Oct 7 08:53:18 2025 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 73944199FAB for ; Fri, 11 Jul 2025 18:37:07 +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=1752259028; cv=none; b=qyjLOdeGy7wfx+9IEsiwx6WMpZ7UUGt+B3CxYYy1uU76wMq9xu0y8tZspoyCdOMJi9oapLgQYAS14BIBC6NlKj6PQ0dfZfJ86CFqPFR6+1Th30aHdNJzg+C5EsODNcpG7Rwnfyo5zm8AP7OCzwraMvT6XgQD/gl8KHBSTWV3C+s= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752259028; c=relaxed/simple; bh=y6aD52A/GXoakeVI754gL5ggJpeMARSE2Wq/EOMb1y0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=DEDOMPdUd4KDGPsjVkQ+xARhWAKqMzkuX5TAMCcEEltb6t7FyTINX+Sm13Sy+vor0w8QKCmkuRw69QGovPbPYWGb3QAV0sAHBH6IvileRNd2dGPdGHd+S6QCFm7cNgY6ZQW62K3pJbGUCsNbL9sNOOtjN+Bxg4fq/iyTO2BBjtE= 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 2B6D016F8; Fri, 11 Jul 2025 11:36:56 -0700 (PDT) Received: from merodach.members.linode.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4C1963F694; Fri, 11 Jul 2025 11:37:03 -0700 (PDT) From: James Morse To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Rob Herring , Ben Horgan , Rohit Mathew , Shanker Donthineni , Zeng Heng , Lecopzer Chen , Carl Worth , shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , 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 , Rex Nie , Dave Martin , Koba Ko , Greg Kroah-Hartman , "Rafael J. Wysocki" , James Morse , Jonathan Cameron , Gavin Shan Subject: [RFC PATCH 01/36] cacheinfo: Set cache 'id' based on DT data Date: Fri, 11 Jul 2025 18:36:13 +0000 Message-Id: <20250711183648.30766-2-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20250711183648.30766-1-james.morse@arm.com> References: <20250711183648.30766-1-james.morse@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Rob Herring Use the minimum CPU h/w id of the CPUs associated with the cache for the cache 'id'. This will provide a stable id value for a given system. As we need to check all possible CPUs, we can't use the shared_cpu_map which is just online CPUs. As there's not a cache to CPUs mapping in DT, we have to walk all CPU nodes and then walk cache levels. The cache_id exposed to user-space has historically been 32 bits, and is too late to change. This value is parsed into a u32 by user-space libraries such as libvirt: https://github.com/libvirt/libvirt/blob/master/src/util/virresctrl.c#L1588 Give up on assigning cache-id's if a CPU h/w id greater than 32 bits is found. match_cache_node() does not make use of the __free() cleanup helpers because of_find_next_cache_node(prev) does not drop a reference to prev, and its too easy to accidentally drop the reference on cpu, which belongs to for_each_of_cpu_node(). Cc: Greg Kroah-Hartman Cc: "Rafael J. Wysocki" Signed-off-by: Rob Herring [ ben: converted to use the __free cleanup idiom ] Signed-off-by: Ben Horgan [ morse: Add checks to give up if a value larger than 32 bits is seen. ] Signed-off-by: James Morse Reviewed-by: Jonathan Cameron Reviewed-by: Gavin Shan --- Use as a 32bit value has also been seen in DPDK patches here: http://inbox.dpdk.org/dev/20241021015246.304431-2-wathsala.vithanage@arm.co= m/ Changes since v2: * Removed broken use of cleanup in the match helper Changes since v1: * Remove the second loop in favour of a helper. --- drivers/base/cacheinfo.c | 45 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c index cf0d455209d7..4e2f60c85e74 100644 --- a/drivers/base/cacheinfo.c +++ b/drivers/base/cacheinfo.c @@ -8,6 +8,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt =20 #include +#include #include #include #include @@ -183,6 +184,49 @@ static bool cache_node_is_unified(struct cacheinfo *th= is_leaf, return of_property_read_bool(np, "cache-unified"); } =20 +static bool match_cache_node(struct device_node *cpu, + const struct device_node *cache_node) +{ + struct device_node *prev, *cache =3D of_find_next_cache_node(cpu); + + while (cache) { + if (cache =3D=3D cache_node) { + of_node_put(cache); + return true; + } + + prev =3D cache; + cache =3D of_find_next_cache_node(cache); + of_node_put(prev); + } + + return false; +} + +static void cache_of_set_id(struct cacheinfo *this_leaf, + struct device_node *cache_node) +{ + struct device_node *cpu; + u32 min_id =3D ~0; + + for_each_of_cpu_node(cpu) { + u64 id =3D of_get_cpu_hwid(cpu, 0); + + if (FIELD_GET(GENMASK_ULL(63, 32), id)) { + of_node_put(cpu); + return; + } + + if (match_cache_node(cpu, cache_node)) + min_id =3D min(min_id, id); + } + + if (min_id !=3D ~0) { + this_leaf->id =3D min_id; + this_leaf->attributes |=3D CACHE_ID; + } +} + static void cache_of_set_props(struct cacheinfo *this_leaf, struct device_node *np) { @@ -198,6 +242,7 @@ static void cache_of_set_props(struct cacheinfo *this_l= eaf, cache_get_line_size(this_leaf, np); cache_nr_sets(this_leaf, np); cache_associativity(this_leaf); + cache_of_set_id(this_leaf, np); } =20 static int cache_setup_of_node(unsigned int cpu) --=20 2.39.5