From nobody Tue Dec 2 02:32:20 2025 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0C5FC35971B; Wed, 19 Nov 2025 12:24:23 +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=1763555066; cv=none; b=TZ3F4tEZeNyxW2KLCjmkjXBr9AAZzYRErIPH4LDPoTsOenDEfCsbrhApdT/ZOdJBRKE8eKFIIivbcR/0kj+OML2sQ9Dgi2oMS0JYCbmDvy/6uAyH/JPFfrcwWvWpOJnE5x62bczww6+RU14V5Aiz1TeL5Gcm3/57IBLTQBiR8Vw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763555066; c=relaxed/simple; bh=zBl185vuMrvlVoNEa6rpWRYO2ZuOQ3iORdRuWf6R9X0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FQqB2bU64FcJp36NKvJg8G5wgY4D8CBllTaJlpMDAyk+KP2nkCHbfutys/LWSaJO9dJQxiZx3mJBMox7+XWljrPQOjr/ZJZph5v3+HgOCby/IuH9SUmx0TysDTYMzpGT1fxXb8rccuxwhuf0MqB+Laal3pR+FUUWsOm4tMdmtFc= 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 C29451A32; Wed, 19 Nov 2025 04:24:15 -0800 (PST) Received: from e134344.cambridge.arm.com (e134344.arm.com [10.1.196.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 2B2A03F740; Wed, 19 Nov 2025 04:24:18 -0800 (PST) From: Ben Horgan To: james.morse@arm.com Cc: amitsinght@marvell.com, baisheng.gao@unisoc.com, baolin.wang@linux.alibaba.com, bobo.shaobowang@huawei.com, carl@os.amperecomputing.com, catalin.marinas@arm.com, dakr@kernel.org, dave.martin@arm.com, david@redhat.com, dfustini@baylibre.com, fenghuay@nvidia.com, gregkh@linuxfoundation.org, gshan@redhat.com, guohanjun@huawei.com, jeremy.linton@arm.com, jonathan.cameron@huawei.com, kobak@nvidia.com, lcherian@marvell.com, lenb@kernel.org, linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, lpieralisi@kernel.org, peternewman@google.com, quic_jiles@quicinc.com, rafael@kernel.org, robh@kernel.org, rohit.mathew@arm.com, scott@os.amperecomputing.com, sdonthineni@nvidia.com, sudeep.holla@arm.com, tan.shaopeng@fujitsu.com, will@kernel.org, xhao@linux.alibaba.com, reinette.chatre@intel.com, Shaopeng Tan , Zeng Heng , Ben Horgan Subject: [PATCH v6 10/34] arm_mpam: Add probe/remove for mpam msc driver and kbuild boiler plate Date: Wed, 19 Nov 2025 12:22:40 +0000 Message-ID: <20251119122305.302149-11-ben.horgan@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251119122305.302149-1-ben.horgan@arm.com> References: <20251119122305.302149-1-ben.horgan@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: James Morse Probing MPAM is convoluted. MSCs that are integrated with a CPU may only be accessible from those CPUs, and they may not be online. Touching the hardware early is pointless as MPAM can't be used until the system-wide common values for num_partid and num_pmg have been discovered. Start with driver probe/remove and mapping the MSC. Cc: Carl Worth Reviewed-by: Jonathan Cameron Reviewed-by: Fenghua Yu Reviewed-by: Shaopeng Tan Tested-by: Fenghua Yu Tested-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Carl Worth Tested-by: Gavin Shan Tested-by: Zeng Heng Tested-by: Hanjun Guo Signed-off-by: James Morse Signed-off-by: Ben Horgan --- Changes since v4: Gavin: if formatting comment/msg clarity make update_msc_accessibility() return void Return -EINVAL if not MMIO interface Jonathan: Whitespace changes Simplify mpam_msc_drv_probe() by returning early on error Changes since v3: From Jonathan: Include cleanup Use devm_mutex_init() Add an ERR_CAST() Fenghua: Return zero from update_msc_accessibility() Additional: Fail probe if MSC doesn't have an MMIO interface --- arch/arm64/Kconfig | 1 + drivers/Kconfig | 2 + drivers/Makefile | 1 + drivers/resctrl/Kconfig | 15 +++ drivers/resctrl/Makefile | 4 + drivers/resctrl/mpam_devices.c | 190 ++++++++++++++++++++++++++++++++ drivers/resctrl/mpam_internal.h | 49 ++++++++ 7 files changed, 262 insertions(+) create mode 100644 drivers/resctrl/Kconfig create mode 100644 drivers/resctrl/Makefile create mode 100644 drivers/resctrl/mpam_devices.c create mode 100644 drivers/resctrl/mpam_internal.h diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index c5e66d5d72cd..004d58cfbff8 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -2025,6 +2025,7 @@ config ARM64_TLB_RANGE =20 config ARM64_MPAM bool "Enable support for MPAM" + select ARM64_MPAM_DRIVER if EXPERT # does nothing yet select ACPI_MPAM if ACPI help Memory System Resource Partitioning and Monitoring (MPAM) is an diff --git a/drivers/Kconfig b/drivers/Kconfig index 4915a63866b0..3054b50a2f4c 100644 --- a/drivers/Kconfig +++ b/drivers/Kconfig @@ -251,4 +251,6 @@ source "drivers/hte/Kconfig" =20 source "drivers/cdx/Kconfig" =20 +source "drivers/resctrl/Kconfig" + endmenu diff --git a/drivers/Makefile b/drivers/Makefile index 8e1ffa4358d5..20eb17596b89 100644 --- a/drivers/Makefile +++ b/drivers/Makefile @@ -194,6 +194,7 @@ obj-$(CONFIG_HTE) +=3D hte/ obj-$(CONFIG_DRM_ACCEL) +=3D accel/ obj-$(CONFIG_CDX_BUS) +=3D cdx/ obj-$(CONFIG_DPLL) +=3D dpll/ +obj-y +=3D resctrl/ =20 obj-$(CONFIG_DIBS) +=3D dibs/ obj-$(CONFIG_S390) +=3D s390/ diff --git a/drivers/resctrl/Kconfig b/drivers/resctrl/Kconfig new file mode 100644 index 000000000000..5f7f748e611e --- /dev/null +++ b/drivers/resctrl/Kconfig @@ -0,0 +1,15 @@ +menuconfig ARM64_MPAM_DRIVER + bool "MPAM driver" + depends on ARM64 && ARM64_MPAM && EXPERT + help + Memory System Resource Partitioning and Monitoring (MPAM) driver for + System IP, e.g. caches and memory controllers. + +if ARM64_MPAM_DRIVER + +config ARM64_MPAM_DRIVER_DEBUG + bool "Enable debug messages from the MPAM driver" + help + Say yes here to enable debug messages from the MPAM driver. + +endif diff --git a/drivers/resctrl/Makefile b/drivers/resctrl/Makefile new file mode 100644 index 000000000000..898199dcf80d --- /dev/null +++ b/drivers/resctrl/Makefile @@ -0,0 +1,4 @@ +obj-$(CONFIG_ARM64_MPAM_DRIVER) +=3D mpam.o +mpam-y +=3D mpam_devices.o + +ccflags-$(CONFIG_ARM64_MPAM_DRIVER_DEBUG) +=3D -DDEBUG diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c new file mode 100644 index 000000000000..e097e852f9c3 --- /dev/null +++ b/drivers/resctrl/mpam_devices.c @@ -0,0 +1,190 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (C) 2025 Arm Ltd. + +#define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "mpam_internal.h" + +/* + * mpam_list_lock protects the SRCU lists when writing. Once the + * mpam_enabled key is enabled these lists are read-only, + * unless the error interrupt disables the driver. + */ +static DEFINE_MUTEX(mpam_list_lock); +static LIST_HEAD(mpam_all_msc); + +struct srcu_struct mpam_srcu; + +/* + * Number of MSCs that have been probed. Once all MSCs have been probed MP= AM + * can be enabled. + */ +static atomic_t mpam_num_msc; + +/* + * An MSC can control traffic from a set of CPUs, but may only be accessib= le + * from a (hopefully wider) set of CPUs. The common reason for this is pow= er + * management. If all the CPUs in a cluster are in PSCI:CPU_SUSPEND, the + * corresponding cache may also be powered off. By making accesses from + * one of those CPUs, we ensure we don't access a cache that's powered off. + */ +static void update_msc_accessibility(struct mpam_msc *msc) +{ + u32 affinity_id; + int err; + + err =3D device_property_read_u32(&msc->pdev->dev, "cpu_affinity", + &affinity_id); + if (err) + cpumask_copy(&msc->accessibility, cpu_possible_mask); + else + acpi_pptt_get_cpus_from_container(affinity_id, &msc->accessibility); +} + +static void mpam_msc_destroy(struct mpam_msc *msc) +{ + struct platform_device *pdev =3D msc->pdev; + + lockdep_assert_held(&mpam_list_lock); + + list_del_rcu(&msc->all_msc_list); + platform_set_drvdata(pdev, NULL); +} + +static void mpam_msc_drv_remove(struct platform_device *pdev) +{ + struct mpam_msc *msc =3D platform_get_drvdata(pdev); + + mutex_lock(&mpam_list_lock); + mpam_msc_destroy(msc); + mutex_unlock(&mpam_list_lock); + + synchronize_srcu(&mpam_srcu); +} + +static struct mpam_msc *do_mpam_msc_drv_probe(struct platform_device *pdev) +{ + int err; + u32 tmp; + struct mpam_msc *msc; + struct resource *msc_res; + struct device *dev =3D &pdev->dev; + + lockdep_assert_held(&mpam_list_lock); + + msc =3D devm_kzalloc(&pdev->dev, sizeof(*msc), GFP_KERNEL); + if (!msc) + return ERR_PTR(-ENOMEM); + + err =3D devm_mutex_init(dev, &msc->probe_lock); + if (err) + return ERR_PTR(err); + + err =3D devm_mutex_init(dev, &msc->part_sel_lock); + if (err) + return ERR_PTR(err); + + msc->id =3D pdev->id; + msc->pdev =3D pdev; + INIT_LIST_HEAD_RCU(&msc->all_msc_list); + INIT_LIST_HEAD_RCU(&msc->ris); + + update_msc_accessibility(msc); + if (cpumask_empty(&msc->accessibility)) { + dev_err_once(dev, "MSC is not accessible from any CPU!"); + return ERR_PTR(-EINVAL); + } + + if (device_property_read_u32(&pdev->dev, "pcc-channel", &tmp)) + msc->iface =3D MPAM_IFACE_MMIO; + else + msc->iface =3D MPAM_IFACE_PCC; + + if (msc->iface =3D=3D MPAM_IFACE_MMIO) { + void __iomem *io; + + io =3D devm_platform_get_and_ioremap_resource(pdev, 0, + &msc_res); + if (IS_ERR(io)) { + dev_err_once(dev, "Failed to map MSC base address\n"); + return ERR_CAST(io); + } + msc->mapped_hwpage_sz =3D msc_res->end - msc_res->start; + msc->mapped_hwpage =3D io; + } else { + return ERR_PTR(-EINVAL); + } + + list_add_rcu(&msc->all_msc_list, &mpam_all_msc); + platform_set_drvdata(pdev, msc); + + return msc; +} + +static int fw_num_msc; + +static int mpam_msc_drv_probe(struct platform_device *pdev) +{ + int err; + struct mpam_msc *msc =3D NULL; + void *plat_data =3D pdev->dev.platform_data; + + mutex_lock(&mpam_list_lock); + msc =3D do_mpam_msc_drv_probe(pdev); + mutex_unlock(&mpam_list_lock); + + if (IS_ERR(msc)) + return PTR_ERR(msc); + + /* Create RIS entries described by firmware */ + err =3D acpi_mpam_parse_resources(msc, plat_data); + if (err) { + mpam_msc_drv_remove(pdev); + return err; + } + + if (atomic_add_return(1, &mpam_num_msc) =3D=3D fw_num_msc) + pr_info("Discovered all MSCs\n"); + + return 0; +} + +static struct platform_driver mpam_msc_driver =3D { + .driver =3D { + .name =3D "mpam_msc", + }, + .probe =3D mpam_msc_drv_probe, + .remove =3D mpam_msc_drv_remove, +}; + +static int __init mpam_msc_driver_init(void) +{ + if (!system_supports_mpam()) + return -EOPNOTSUPP; + + init_srcu_struct(&mpam_srcu); + + fw_num_msc =3D acpi_mpam_count_msc(); + if (fw_num_msc <=3D 0) { + pr_err("No MSC devices found in firmware\n"); + return -EINVAL; + } + + return platform_driver_register(&mpam_msc_driver); +} +subsys_initcall(mpam_msc_driver_init); diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_interna= l.h new file mode 100644 index 000000000000..540066903eca --- /dev/null +++ b/drivers/resctrl/mpam_internal.h @@ -0,0 +1,49 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +// Copyright (C) 2025 Arm Ltd. + +#ifndef MPAM_INTERNAL_H +#define MPAM_INTERNAL_H + +#include +#include +#include +#include +#include + +struct platform_device; + +struct mpam_msc { + /* member of mpam_all_msc */ + struct list_head all_msc_list; + + int id; + struct platform_device *pdev; + + /* Not modified after mpam_is_enabled() becomes true */ + enum mpam_msc_iface iface; + u32 nrdy_usec; + cpumask_t accessibility; + + /* + * probe_lock is only taken during discovery. After discovery these + * properties become read-only and the lists are protected by SRCU. + */ + struct mutex probe_lock; + unsigned long ris_idxs; + u32 ris_max; + + /* mpam_msc_ris of this component */ + struct list_head ris; + + /* + * part_sel_lock protects access to the MSC hardware registers that are + * affected by MPAMCFG_PART_SEL. (including the ID registers that vary + * by RIS). + * If needed, take msc->probe_lock first. + */ + struct mutex part_sel_lock; + + void __iomem *mapped_hwpage; + size_t mapped_hwpage_sz; +}; +#endif /* MPAM_INTERNAL_H */ --=20 2.43.0