From nobody Wed Nov 27 02:44:03 2024 Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) (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 F0CFB167296 for ; Tue, 15 Oct 2024 02:19:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.191 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728958745; cv=none; b=RXiJCg+UexiR/epM1tXbw/pUmG/cWaTRdU52TJgevb3b8FAo28ylnR9ErSU+2sz1+vm638rM5JaE8HJFZ9nSDYUMXQyPuV2u4PgJXgXTcVyjUrPQ/Zbs4nSDY6bYWZ+VkGKNDRL4+q13cSganbpYtkFqvgDgeq3dmHsohNfm6jo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728958745; c=relaxed/simple; bh=mMW/Z4O9V0vIOpiEhnAH9m7xEpXakLGxijQ85U0Du6A=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=XLLDPDNdUQTLdZ/VyzxQKjRj+XC4O5cm2tTZQU2xA5AMyMXT9YEABDF3Y13+aNgF/qo91Rc09iYDsb1ASW7rVIwqrX19assDbqWGHd8vF9N0t1h3ElQ+PvUqxT9BWVbVbKZrLFDwEFZ0QhwL4hnF1jZk/Ftpp8loxQRDYhAbfMM= 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=45.249.212.191 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 [172.19.162.112]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4XSHn84z2Qz1j9wx; Tue, 15 Oct 2024 10:17:48 +0800 (CST) Received: from kwepemd200014.china.huawei.com (unknown [7.221.188.8]) by mail.maildlp.com (Postfix) with ESMTPS id F26161400D4; Tue, 15 Oct 2024 10:19:00 +0800 (CST) Received: from localhost.localdomain (10.50.165.33) by kwepemd200014.china.huawei.com (7.221.188.8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.34; Tue, 15 Oct 2024 10:19:00 +0800 From: Yicong Yang To: , , , , , , , , , , , CC: , , , , , , , , , , , , Subject: [PATCH v6 3/4] arm64: topology: Support SMT control on ACPI based system Date: Tue, 15 Oct 2024 10:18:40 +0800 Message-ID: <20241015021841.35713-4-yangyicong@huawei.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20241015021841.35713-1-yangyicong@huawei.com> References: <20241015021841.35713-1-yangyicong@huawei.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 X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemd200014.china.huawei.com (7.221.188.8) Content-Type: text/plain; charset="utf-8" From: Yicong Yang For ACPI we'll build the topology from PPTT and we cannot directly get the SMT number of each core. Instead using a temporary xarray to record the heterogeneous information (from ACPI_PPTT_ACPI_IDENTICAL) and SMT information of the first core in its heterogeneous CPU cluster when building the topology. Then we can know the largest SMT number in the system. The core's SMT control provides two interface to the users [1]: 1) enable/disable SMT by writing on/off 2) enable/disable SMT by writing thread number 1/max_thread_number If a system have more than one SMT thread number the 2) may not handle it well, since there're multiple thread numbers in the system and 2) only accept 1/max_thread_number. So issue a warning to notify the users if such system detected. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree= /Documentation/ABI/testing/sysfs-devices-system-cpu#n542 Signed-off-by: Yicong Yang --- arch/arm64/kernel/topology.c | 61 ++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 1a2c72f3e7f8..2fa584b932ee 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -15,8 +15,10 @@ #include #include #include +#include #include #include +#include =20 #include #include @@ -37,17 +39,29 @@ static bool __init acpi_cpu_is_threaded(int cpu) return !!is_threaded; } =20 +struct cpu_smt_info { + int thread_num; + int core_id; + int cpu; +}; + /* * Propagate the topology information of the processor_topology_node tree = to the * cpu_topology array. */ int __init parse_acpi_topology(void) { + int max_smt_thread_num =3D 0; + struct cpu_smt_info *entry; + struct xarray hetero_cpu; + unsigned long hetero_id; int cpu, topology_id; =20 if (acpi_disabled) return 0; =20 + xa_init(&hetero_cpu); + for_each_possible_cpu(cpu) { topology_id =3D find_acpi_cpu_topology(cpu, 0); if (topology_id < 0) @@ -57,6 +71,30 @@ int __init parse_acpi_topology(void) cpu_topology[cpu].thread_id =3D topology_id; topology_id =3D find_acpi_cpu_topology(cpu, 1); cpu_topology[cpu].core_id =3D topology_id; + + /* + * Build up the XArray using the heterogeneous ID of + * the CPU cluster. Store the CPU and SMT information + * of the first appeared CPU in the CPU cluster of this + * heterogeneous ID since the SMT information should be + * the same in this CPU cluster. Then we can know the + * SMT information of each heterogeneous CPUs in the + * system. + */ + hetero_id =3D find_acpi_cpu_topology_hetero_id(cpu); + entry =3D (struct cpu_smt_info *)xa_load(&hetero_cpu, hetero_id); + if (!entry) { + entry =3D kzalloc(sizeof(*entry), GFP_KERNEL); + WARN_ON(!entry); + + entry->cpu =3D cpu; + entry->core_id =3D topology_id; + entry->thread_num =3D 1; + xa_store(&hetero_cpu, hetero_id, + entry, GFP_KERNEL); + } else if (entry->core_id =3D=3D topology_id) { + entry->thread_num++; + } } else { cpu_topology[cpu].thread_id =3D -1; cpu_topology[cpu].core_id =3D topology_id; @@ -67,6 +105,29 @@ int __init parse_acpi_topology(void) cpu_topology[cpu].package_id =3D topology_id; } =20 + /* + * This should be a short loop depending on the number of heterogeneous + * CPU clusters. Typically on a homogeneous system there's only one + * entry in the XArray. + */ + xa_for_each(&hetero_cpu, hetero_id, entry) { + /* + * If max_smt_thread_num has been initialized and doesn't match + * the thread number of this entry, then the system has + * heterogeneous SMT topology. + */ + if (entry->thread_num !=3D max_smt_thread_num && max_smt_thread_num) + pr_warn_once("Heterogeneous SMT topology is partly supported by SMT con= trol\n"); + + if (entry->thread_num > max_smt_thread_num) + max_smt_thread_num =3D entry->thread_num; + + xa_erase(&hetero_cpu, hetero_id); + kfree(entry); + } + + cpu_smt_set_num_threads(max_smt_thread_num, max_smt_thread_num); + xa_destroy(&hetero_cpu); return 0; } #endif --=20 2.24.0