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 D5DEA3054CA; Mon, 1 Sep 2025 09:11:37 +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=1756717900; cv=none; b=dKIPH5j1jO8KybsHCDYf6j2XSOT74jwCw5wG70OANekbUuSuDJCEd6qNDQlClvlElKpFGp9oHcHM18LXjxTQe8xANHGdR0/jI3MZCofFalY0aQzVvnJwv/CJWfNhNsfEzEgoUARDV5yUAiOT1PYWzOV8/h5RmRs/RtTkwffD5xQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756717900; c=relaxed/simple; bh=E5Lalbcg4v2zCi2EiEUCXwPTHYCLtDY2UGfJyj3pW94=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ORctstrM75iNuFsVbnEBmcY8kHUg3K+xs4ZI93lU+0ETiOOXXgT3kPNyVpx7zy5w8VBeoyMs4IOSHHDv/7HG8zL4PQDWnIpmwfPaXREzcV45PNfmEu4xr/md58zNpF20xHAnwYg1w7tRrQXcXZiL+OFikIgvgmvDt6Yv0ICBkl4= 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 AA0011A25; Mon, 1 Sep 2025 02:11:28 -0700 (PDT) Received: from [10.1.196.46] (e134344.arm.com [10.1.196.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B12733F694; Mon, 1 Sep 2025 02:11:31 -0700 (PDT) Message-ID: Date: Mon, 1 Sep 2025 10:11:30 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 10/33] arm_mpam: Add probe/remove for mpam msc driver and kbuild boiler plate To: James Morse , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, devicetree@vger.kernel.org Cc: shameerali.kolothum.thodi@huawei.com, 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 , Rex Nie , Dave Martin , Koba Ko , Shanker Donthineni , fenghuay@nvidia.com, baisheng.gao@unisoc.com, Jonathan Cameron , Rob Herring , Rohit Mathew , Rafael Wysocki , Len Brown , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Krzysztof Kozlowski , Conor Dooley , Catalin Marinas , Will Deacon , Greg Kroah-Hartman , Danilo Krummrich References: <20250822153048.2287-1-james.morse@arm.com> <20250822153048.2287-11-james.morse@arm.com> From: Ben Horgan Content-Language: en-US In-Reply-To: <20250822153048.2287-11-james.morse@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi James, On 8/22/25 16:29, James Morse wrote: > 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 > Signed-off-by: James Morse > --- > Changes since RFC: > * Check for status=broken DT devices. > * Moved all the files around. > * Made Kconfig symbols depend on EXPERT > --- > arch/arm64/Kconfig | 1 + > drivers/Kconfig | 2 + > drivers/Makefile | 1 + > drivers/resctrl/Kconfig | 11 ++ > drivers/resctrl/Makefile | 4 + > drivers/resctrl/mpam_devices.c | 336 ++++++++++++++++++++++++++++++++ > drivers/resctrl/mpam_internal.h | 62 ++++++ > 7 files changed, 417 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 e51ccf1da102..ea3c54e04275 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -2062,6 +2062,7 @@ config ARM64_TLB_RANGE > > config ARM64_MPAM > bool "Enable support for MPAM" > + select ARM64_MPAM_DRIVER > select ACPI_MPAM if ACPI > help > Memory Partitioning and Monitoring is an optional extension > 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" > > source "drivers/cdx/Kconfig" > > +source "drivers/resctrl/Kconfig" > + > endmenu > diff --git a/drivers/Makefile b/drivers/Makefile > index b5749cf67044..f41cf4eddeba 100644 > --- a/drivers/Makefile > +++ b/drivers/Makefile > @@ -194,5 +194,6 @@ obj-$(CONFIG_HTE) += hte/ > obj-$(CONFIG_DRM_ACCEL) += accel/ > obj-$(CONFIG_CDX_BUS) += cdx/ > obj-$(CONFIG_DPLL) += dpll/ > +obj-y += resctrl/ > > obj-$(CONFIG_S390) += s390/ > diff --git a/drivers/resctrl/Kconfig b/drivers/resctrl/Kconfig > new file mode 100644 > index 000000000000..dff7b87280ab > --- /dev/null > +++ b/drivers/resctrl/Kconfig > @@ -0,0 +1,11 @@ > +# Confusingly, this is everything but the CPU bits of MPAM. CPU here means > +# CPU resources, not containers or cgroups etc. > +config ARM64_MPAM_DRIVER > + bool "MPAM driver for System IP, e,g. caches and memory controllers" > + depends on ARM64_MPAM && EXPERT > + > +config ARM64_MPAM_DRIVER_DEBUG > + bool "Enable debug messages from the MPAM driver." > + depends on ARM64_MPAM_DRIVER > + help > + Say yes here to enable debug messages from the MPAM driver. > diff --git a/drivers/resctrl/Makefile b/drivers/resctrl/Makefile > new file mode 100644 > index 000000000000..92b48fa20108 > --- /dev/null > +++ b/drivers/resctrl/Makefile > @@ -0,0 +1,4 @@ > +obj-$(CONFIG_ARM64_MPAM_DRIVER) += mpam.o > +mpam-y += mpam_devices.o > + > +cflags-$(CONFIG_ARM64_MPAM_DRIVER_DEBUG) += -DDEBUG > diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c > new file mode 100644 > index 000000000000..a0d9a699a6e7 > --- /dev/null > +++ b/drivers/resctrl/mpam_devices.c > @@ -0,0 +1,336 @@ > +// 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 > +#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); > + > +static struct srcu_struct mpam_srcu; > + > +/* MPAM isn't available until all the MSC have been probed. */ > +static u32 mpam_num_msc; > + > +static void mpam_discovery_complete(void) > +{ > + pr_err("Discovered all MSC\n"); > +} > + > +static int mpam_dt_count_msc(void) > +{ > + int count = 0; > + struct device_node *np; > + > + for_each_compatible_node(np, NULL, "arm,mpam-msc") { > + if (of_device_is_available(np)) > + count++; > + } > + > + return count; > +} > + > +static int mpam_dt_parse_resource(struct mpam_msc *msc, struct device_node *np, > + u32 ris_idx) > +{ > + int err = 0; > + u32 level = 0; > + unsigned long cache_id; > + struct device_node *cache; > + > + do { > + if (of_device_is_compatible(np, "arm,mpam-cache")) { > + cache = of_parse_phandle(np, "arm,mpam-device", 0); > + if (!cache) { > + pr_err("Failed to read phandle\n"); > + break; > + } > + } else if (of_device_is_compatible(np->parent, "cache")) { > + cache = of_node_get(np->parent); > + } else { > + /* For now, only caches are supported */ > + cache = NULL; > + break; > + } > + > + err = of_property_read_u32(cache, "cache-level", &level); > + if (err) { > + pr_err("Failed to read cache-level\n"); > + break; > + } > + > + cache_id = cache_of_calculate_id(cache); > + if (cache_id == ~0UL) { > + err = -ENOENT; > + break; > + } > + > + err = mpam_ris_create(msc, ris_idx, MPAM_CLASS_CACHE, level, > + cache_id); > + } while (0); > + of_node_put(cache); > + > + return err; > +} > + > +static int mpam_dt_parse_resources(struct mpam_msc *msc, void *ignored) > +{ > + int err, num_ris = 0; > + const u32 *ris_idx_p; > + struct device_node *iter, *np; > + > + np = msc->pdev->dev.of_node; > + for_each_child_of_node(np, iter) { > + ris_idx_p = of_get_property(iter, "reg", NULL); > + if (ris_idx_p) { > + num_ris++; > + err = mpam_dt_parse_resource(msc, iter, *ris_idx_p); > + if (err) { > + of_node_put(iter); > + return err; > + } > + } > + } > + > + if (!num_ris) > + mpam_dt_parse_resource(msc, np, 0); > + > + return err; > +} > + > +/* > + * An MSC can control traffic from a set of CPUs, but may only be accessible > + * from a (hopefully wider) set of CPUs. The common reason for this is power > + * management. If all the CPUs in a cluster are in PSCI:CPU_SUSPEND, the > + * the corresponding cache may also be powered off. By making accesses from > + * one of those CPUs, we ensure this isn't the case. > + */ > +static int update_msc_accessibility(struct mpam_msc *msc) > +{ > + struct device_node *parent; > + u32 affinity_id; > + int err; > + > + if (!acpi_disabled) { > + err = 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); > + > + return 0; > + } > + > + /* This depends on the path to of_node */ > + parent = of_get_parent(msc->pdev->dev.of_node); > + if (parent == of_root) { > + cpumask_copy(&msc->accessibility, cpu_possible_mask); > + err = 0; > + } else { > + err = -EINVAL; > + pr_err("Cannot determine accessibility of MSC: %s\n", > + dev_name(&msc->pdev->dev)); > + } > + of_node_put(parent); > + > + return err; > +} > + > +static int fw_num_msc; > + > +static void mpam_pcc_rx_callback(struct mbox_client *cl, void *msg) > +{ > + /* TODO: wake up tasks blocked on this MSC's PCC channel */ > +} > + > +static void mpam_msc_drv_remove(struct platform_device *pdev) > +{ > + struct mpam_msc *msc = platform_get_drvdata(pdev); > + > + if (!msc) > + return; > + > + mutex_lock(&mpam_list_lock); > + mpam_num_msc--; > + platform_set_drvdata(pdev, NULL); > + list_del_rcu(&msc->glbl_list); > + synchronize_srcu(&mpam_srcu); > + devm_kfree(&pdev->dev, msc); > + mutex_unlock(&mpam_list_lock); > +} > + > +static int mpam_msc_drv_probe(struct platform_device *pdev) > +{ > + int err; > + struct mpam_msc *msc; > + struct resource *msc_res; > + void *plat_data = pdev->dev.platform_data; > + > + mutex_lock(&mpam_list_lock); > + do { > + msc = devm_kzalloc(&pdev->dev, sizeof(*msc), GFP_KERNEL); > + if (!msc) { > + err = -ENOMEM; > + break; > + } > + > + mutex_init(&msc->probe_lock); > + mutex_init(&msc->part_sel_lock); > + mutex_init(&msc->outer_mon_sel_lock); > + raw_spin_lock_init(&msc->inner_mon_sel_lock); > + msc->id = mpam_num_msc++; > + msc->pdev = pdev; > + INIT_LIST_HEAD_RCU(&msc->glbl_list); > + INIT_LIST_HEAD_RCU(&msc->ris); > + > + err = update_msc_accessibility(msc); > + if (err) > + break; > + if (cpumask_empty(&msc->accessibility)) { > + pr_err_once("msc:%u is not accessible from any CPU!", > + msc->id); > + err = -EINVAL; > + break; > + } > + > + if (device_property_read_u32(&pdev->dev, "pcc-channel", > + &msc->pcc_subspace_id)) > + msc->iface = MPAM_IFACE_MMIO; > + else > + msc->iface = MPAM_IFACE_PCC; > + > + if (msc->iface == MPAM_IFACE_MMIO) { > + void __iomem *io; > + > + io = devm_platform_get_and_ioremap_resource(pdev, 0, > + &msc_res); > + if (IS_ERR(io)) { > + pr_err("Failed to map MSC base address\n"); > + err = PTR_ERR(io); > + break; > + } > + msc->mapped_hwpage_sz = msc_res->end - msc_res->start; > + msc->mapped_hwpage = io; > + } else if (msc->iface == MPAM_IFACE_PCC) { > + msc->pcc_cl.dev = &pdev->dev; > + msc->pcc_cl.rx_callback = mpam_pcc_rx_callback; > + msc->pcc_cl.tx_block = false; > + msc->pcc_cl.tx_tout = 1000; /* 1s */ > + msc->pcc_cl.knows_txdone = false; > + > + msc->pcc_chan = pcc_mbox_request_channel(&msc->pcc_cl, > + msc->pcc_subspace_id); > + if (IS_ERR(msc->pcc_chan)) { > + pr_err("Failed to request MSC PCC channel\n"); > + err = PTR_ERR(msc->pcc_chan); > + break; > + } > + } > + > + list_add_rcu(&msc->glbl_list, &mpam_all_msc); > + platform_set_drvdata(pdev, msc); > + } while (0); > + mutex_unlock(&mpam_list_lock); > + > + if (!err) { > + /* Create RIS entries described by firmware */ > + if (!acpi_disabled) > + err = acpi_mpam_parse_resources(msc, plat_data); > + else > + err = mpam_dt_parse_resources(msc, plat_data); > + } > + > + if (!err && fw_num_msc == mpam_num_msc) > + mpam_discovery_complete(); > + > + if (err && msc) > + mpam_msc_drv_remove(pdev); > + > + return err; > +} > + > +static const struct of_device_id mpam_of_match[] = { > + { .compatible = "arm,mpam-msc", }, > + {}, > +}; > +MODULE_DEVICE_TABLE(of, mpam_of_match); > + > +static struct platform_driver mpam_msc_driver = { > + .driver = { > + .name = "mpam_msc", > + .of_match_table = of_match_ptr(mpam_of_match), > + }, > + .probe = mpam_msc_drv_probe, > + .remove = mpam_msc_drv_remove, > +}; > + > +/* > + * MSC that are hidden under caches are not created as platform devices > + * as there is no cache driver. Caches are also special-cased in > + * update_msc_accessibility(). > + */ > +static void mpam_dt_create_foundling_msc(void) > +{ > + int err; > + struct device_node *cache; > + > + for_each_compatible_node(cache, NULL, "cache") { > + err = of_platform_populate(cache, mpam_of_match, NULL, NULL); > + if (err) > + pr_err("Failed to create MSC devices under caches\n"); > + } > +} > + > +static int __init mpam_msc_driver_init(void) > +{ > + if (!system_supports_mpam()) > + return -EOPNOTSUPP; > + > + init_srcu_struct(&mpam_srcu); > + > + if (!acpi_disabled) > + fw_num_msc = acpi_mpam_count_msc(); > + else > + fw_num_msc = mpam_dt_count_msc(); > + > + if (fw_num_msc <= 0) { > + pr_err("No MSC devices found in firmware\n"); > + return -EINVAL; > + } > + > + if (acpi_disabled) > + mpam_dt_create_foundling_msc(); > + > + 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_internal.h > new file mode 100644 > index 000000000000..07e0f240eaca > --- /dev/null > +++ b/drivers/resctrl/mpam_internal.h > @@ -0,0 +1,62 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +// Copyright (C) 2024 Arm Ltd. > + > +#ifndef MPAM_INTERNAL_H > +#define MPAM_INTERNAL_H > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +struct mpam_msc { > + /* member of mpam_all_msc */ > + struct list_head glbl_list; > + > + int id; > + struct platform_device *pdev; > + > + /* Not modified after mpam_is_enabled() becomes true */ > + enum mpam_msc_iface iface; > + u32 pcc_subspace_id; > + struct mbox_client pcc_cl; > + struct pcc_mbox_chan *pcc_chan; > + u32 nrdy_usec; > + cpumask_t accessibility; > + > + /* > + * probe_lock is only take during discovery. After discovery these > + * properties become read-only and the lists are protected by SRCU. > + */ > + struct mutex probe_lock; > + unsigned long ris_idxs[128 / BITS_PER_LONG]; Why is this sized this way? RIS_MAX is 4 bits and so there are at most 16 RIS per msc. > + 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->lock first. > + */ > + struct mutex part_sel_lock; > + > + /* > + * mon_sel_lock protects access to the MSC hardware registers that are > + * affeted by MPAMCFG_MON_SEL. > + * If needed, take msc->lock first. > + */ > + struct mutex outer_mon_sel_lock; > + raw_spinlock_t inner_mon_sel_lock; > + unsigned long inner_mon_sel_flags; > + > + void __iomem *mapped_hwpage; > + size_t mapped_hwpage_sz; > +}; > + > +#endif /* MPAM_INTERNAL_H */ Thanks, Ben