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 A5752EB1049 for ; Tue, 10 Mar 2026 10:34:27 +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:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=8WaDDT20xUGl6yGh5IPza+ltaEnUO/3lX2to0edzDu0=; b=Ef+wacL1OgDMwdISZdWRdRt5Du gxnFt6on5669ED0VOXegOI59QiFNoSHBxZP7xi7BkWsJPiJkd3kO+ahQL0vv5HIjpl0/wHfCEJ1Ka 7oHQlRW4KjoiJOjdG7XA8WOKFGg/6B2gPito3mQFEDzU5wdf8GomTeG6PO6GZLaNLAbxsNWRcC0R5 cHULdXowKBRcGLuhkrCAcSc7iPw6qqRlI/WChhwBvUFQJG07KRY338eTCPWNr8Hf8pP2GyobrEJgq CCSZ+1aRciauNwQLwTtqfJX2U13X/sqJNXaN3hxbjbRV7TiEAPES4r0n7//THvZn80Es7mIeUyxvm jlScJvPg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vzuPt-00000009D2j-2xRz; Tue, 10 Mar 2026 10:34:21 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vzuPq-00000009D2E-3OQ1 for linux-arm-kernel@lists.infradead.org; Tue, 10 Mar 2026 10:34:20 +0000 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 3136F14BF; Tue, 10 Mar 2026 03:34:10 -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 80AFA3F7BD; Tue, 10 Mar 2026 03:34:12 -0700 (PDT) Message-ID: Date: Tue, 10 Mar 2026 10:34:11 +0000 MIME-Version: 1.0 User-Agent: Thunderbird Daily Subject: Re: [PATCH v5 13/41] arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation To: Gavin Shan Cc: amitsinght@marvell.com, baisheng.gao@unisoc.com, baolin.wang@linux.alibaba.com, carl@os.amperecomputing.com, dave.martin@arm.com, david@kernel.org, dfustini@baylibre.com, fenghuay@nvidia.com, james.morse@arm.com, jonathan.cameron@huawei.com, kobak@nvidia.com, lcherian@marvell.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, peternewman@google.com, punit.agrawal@oss.qualcomm.com, quic_jiles@quicinc.com, reinette.chatre@intel.com, rohit.mathew@arm.com, scott@os.amperecomputing.com, sdonthineni@nvidia.com, tan.shaopeng@fujitsu.com, xhao@linux.alibaba.com, catalin.marinas@arm.com, will@kernel.org, corbet@lwn.net, maz@kernel.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, kvmarm@lists.linux.dev, zengheng4@huawei.com, linux-doc@vger.kernel.org, Shaopeng Tan References: <20260224175720.2663924-1-ben.horgan@arm.com> <20260224175720.2663924-14-ben.horgan@arm.com> <5a1429a6-c551-4d49-ae65-1ac7fd5e4715@redhat.com> Content-Language: en-US From: Ben Horgan In-Reply-To: <5a1429a6-c551-4d49-ae65-1ac7fd5e4715@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260310_033418_941711_8751B892 X-CRM114-Status: GOOD ( 36.51 ) 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 Hi Gavin, On 3/10/26 06:17, Gavin Shan wrote: > Hi Ben, > > On 2/25/26 3:56 AM, Ben Horgan wrote: >> From: James Morse >> >> resctrl has its own data structures to describe its resources. We >> can't use >> these directly as we play tricks with the 'MBA' resource, picking the >> MPAM >> controls or monitors that best apply. We may export the same component as >> both L3 and MBA. >> >> Add mpam_resctrl_res[] as the array of class->resctrl mappings we are >> exporting, and add the cpuhp hooks that allocated and free the resctrl >> domain structures. Only the mpam control feature are considered here and >> monitor support will be added later. >> >> While we're here, plumb in a few other obvious things. >> >> CONFIG_ARM_CPU_RESCTRL is used to allow this code to be built even though >> it can't yet be linked against resctrl. >> > > CONFIG_ARM_CPU_RESCTRL isn't valid. I guess you're probably mentioning > CONFIG_ARCH_HAS_CPU_RESCTRL? CONFIG_ARM_CPU_RESCTRL is added in the Makefile in this patch. As stated, this is just to allow build testing and the link will fail. E.g. $ CONFIG_ARM_CPU_RESCTRL=y make O=out drivers/resctrl/ Trying this now I note there is also a build warning about the 'offline_ctrl_domain' label being unused which I'll fix. > >> Tested-by: Gavin Shan >> Tested-by: Shaopeng Tan >> Tested-by: Peter Newman >> Tested-by: Zeng Heng >> Reviewed-by: Shaopeng Tan >> Reviewed-by: Jonathan Cameron >> Signed-off-by: James Morse >> Signed-off-by: Ben Horgan >> --- >> Changes since rfc: >> Domain list is an rcu list >> Add synchronize_rcu() to free the deleted element >> Code flow simplification (Jonathan) >> >> Changes since v2: >> Iterate over mpam_resctrl_dom directly (Jonathan) >> Code flow clarification >> Comment tidying >> Remove power of 2 check as no longer creates holes in rmid indices >> Remove unused type argument >> add macro helper for_each_mpam_resctrl_control >> >> Changes since v3: >> Add and use mpam_resctrl_online_domain_hdr() >> mpam_resctrl_alloc_domain() error paths (Reinette) >> rebase on x86/cache changes rdt_mon_domain becomes rdt_l3_mon_domain >> etc >> >> Changes since v4: >> Set rid in domain_hdr >> Use rescctrl_res.alloc_capable to determine if alloc_capable as the >> decision may depend on the resctrl mount options (cdp) >> Squash in arm_mpam: resctrl: Sort the order of the domain lists >> Move out monitor/counter changes to a separate patch >> Commit message update >> --- >>   drivers/resctrl/Makefile        |   1 + >>   drivers/resctrl/mpam_devices.c  |  12 ++ >>   drivers/resctrl/mpam_internal.h |  21 ++ >>   drivers/resctrl/mpam_resctrl.c  | 327 ++++++++++++++++++++++++++++++++ >>   include/linux/arm_mpam.h        |   3 + >>   5 files changed, 364 insertions(+) >>   create mode 100644 drivers/resctrl/mpam_resctrl.c >> >> diff --git a/drivers/resctrl/Makefile b/drivers/resctrl/Makefile >> index 898199dcf80d..40beaf999582 100644 >> --- a/drivers/resctrl/Makefile >> +++ b/drivers/resctrl/Makefile >> @@ -1,4 +1,5 @@ >>   obj-$(CONFIG_ARM64_MPAM_DRIVER)            += mpam.o >>   mpam-y                        += mpam_devices.o >> +mpam-$(CONFIG_ARM_CPU_RESCTRL)            += mpam_resctrl.o Here. >>     ccflags-$(CONFIG_ARM64_MPAM_DRIVER_DEBUG)    += -DDEBUG >> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/ >> mpam_devices.c >> index b400a7381d9a..b45743c5fb46 100644 >> --- a/drivers/resctrl/mpam_devices.c >> +++ b/drivers/resctrl/mpam_devices.c >> @@ -1628,6 +1628,9 @@ static int mpam_cpu_online(unsigned int cpu) >>               mpam_reprogram_msc(msc); >>       } >>   +    if (mpam_is_enabled()) >> +        return mpam_resctrl_online_cpu(cpu); >> + >>       return 0; >>   } >>   @@ -1671,6 +1674,9 @@ static int mpam_cpu_offline(unsigned int cpu) >>   { >>       struct mpam_msc *msc; >>   +    if (mpam_is_enabled()) >> +        mpam_resctrl_offline_cpu(cpu); >> + >>       guard(srcu)(&mpam_srcu); >>       list_for_each_entry_srcu(msc, &mpam_all_msc, all_msc_list, >>                    srcu_read_lock_held(&mpam_srcu)) { >> @@ -2516,6 +2522,12 @@ static void mpam_enable_once(void) >>       mutex_unlock(&mpam_list_lock); >>       cpus_read_unlock(); >>   +    if (!err) { >> +        err = mpam_resctrl_setup(); >> +        if (err) >> +            pr_err("Failed to initialise resctrl: %d\n", err); >> +    } >> + >>       if (err) { >>           mpam_disable_reason = "Failed to enable."; >>           schedule_work(&mpam_broken_work); >> diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/ >> mpam_internal.h >> index 4632985bcca6..28ac501e1ac3 100644 >> --- a/drivers/resctrl/mpam_internal.h >> +++ b/drivers/resctrl/mpam_internal.h >> @@ -12,6 +12,7 @@ >>   #include >>   #include >>   #include >> +#include >>   #include >>   #include >>   #include >> @@ -337,6 +338,16 @@ struct mpam_msc_ris { >>       struct mpam_garbage    garbage; >>   }; >>   +struct mpam_resctrl_dom { >> +    struct mpam_component        *ctrl_comp; >> +    struct rdt_ctrl_domain        resctrl_ctrl_dom; >> +}; >> + >> +struct mpam_resctrl_res { >> +    struct mpam_class    *class; >> +    struct rdt_resource    resctrl_res; >> +}; >> + >>   static inline int mpam_alloc_csu_mon(struct mpam_class *class) >>   { >>       struct mpam_props *cprops = &class->props; >> @@ -391,6 +402,16 @@ void mpam_msmon_reset_mbwu(struct mpam_component >> *comp, struct mon_cfg *ctx); >>   int mpam_get_cpumask_from_cache_id(unsigned long cache_id, u32 >> cache_level, >>                      cpumask_t *affinity); >>   +#ifdef CONFIG_RESCTRL_FS >> +int mpam_resctrl_setup(void); >> +int mpam_resctrl_online_cpu(unsigned int cpu); >> +void mpam_resctrl_offline_cpu(unsigned int cpu); >> +#else >> +static inline int mpam_resctrl_setup(void) { return 0; } >> +static inline int mpam_resctrl_online_cpu(unsigned int cpu) { return >> 0; } >> +static inline void mpam_resctrl_offline_cpu(unsigned int cpu) { } >> +#endif /* CONFIG_RESCTRL_FS */ >> + >>   /* >>    * MPAM MSCs have the following register layout. See: >>    * Arm Memory System Resource Partitioning and Monitoring (MPAM) System >> diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/ >> mpam_resctrl.c >> new file mode 100644 >> index 000000000000..2ffba7a15d6a >> --- /dev/null >> +++ b/drivers/resctrl/mpam_resctrl.c >> @@ -0,0 +1,327 @@ >> +// 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 "mpam_internal.h" >> + > > The list of included headers could be simplified since several header files > have been included to mpam_internal.h, for example , > , and others. Could be but it is a deliberate choice to where practical include the header where the symbols are defined rather than relying on the indirect includes. > >> +/* >> + * The classes we've picked to map to resctrl resources, wrapped >> + * in with their resctrl structure. >> + * Class pointer may be NULL. >> + */ >> +static struct mpam_resctrl_res mpam_resctrl_controls[RDT_NUM_RESOURCES]; >> + >> +#define for_each_mpam_resctrl_control(res, rid)                    \ >> +    for (rid = 0, res = &mpam_resctrl_controls[rid];            \ >> +         rid < RDT_NUM_RESOURCES;                        \ >> +         rid++, res = &mpam_resctrl_controls[rid]) >> + >> +/* The lock for modifying resctrl's domain lists from cpuhp >> callbacks. */ >> +static DEFINE_MUTEX(domain_list_lock); >> + >> +bool resctrl_arch_alloc_capable(void) >> +{ >> +    struct mpam_resctrl_res *res; >> +    enum resctrl_res_level rid; >> + >> +    for_each_mpam_resctrl_control(res, rid) { >> +        if (res->resctrl_res.alloc_capable) >> +            return true; >> +    } >> + >> +    return false; >> +} >> + >> +/* >> + * MSC may raise an error interrupt if it sees an out or range >> partid/pmg, >> + * and go on to truncate the value. Regardless of what the hardware >> supports, >> + * only the system wide safe value is safe to use. >> + */ >> +u32 resctrl_arch_get_num_closid(struct rdt_resource *ignored) >> +{ >> +    return mpam_partid_max + 1; >> +} >> + >> +struct rdt_resource *resctrl_arch_get_resource(enum resctrl_res_level l) >> +{ >> +    if (l >= RDT_NUM_RESOURCES) >> +        return NULL; >> + >> +    return &mpam_resctrl_controls[l].resctrl_res; >> +} >> + >> +static int mpam_resctrl_control_init(struct mpam_resctrl_res *res) >> +{ >> +    /* TODO: initialise the resctrl resources */ >> + >> +    return 0; >> +} >> + >> +static int mpam_resctrl_pick_domain_id(int cpu, struct mpam_component >> *comp) >> +{ >> +    struct mpam_class *class = comp->class; >> + >> +    if (class->type == MPAM_CLASS_CACHE) >> +        return comp->comp_id; >> + >> +    /* TODO: repaint domain ids to match the L3 domain ids */ >> +    /* Otherwise, expose the ID used by the firmware table code. */ >> +    return comp->comp_id; >> +} >> + >> +static void mpam_resctrl_domain_hdr_init(int cpu, struct >> mpam_component *comp, >> +                     enum resctrl_res_level rid, >> +                     struct rdt_domain_hdr *hdr) >> +{ >> +    lockdep_assert_cpus_held(); >> + >> +    INIT_LIST_HEAD(&hdr->list); >> +    hdr->id = mpam_resctrl_pick_domain_id(cpu, comp); >> +    hdr->rid = rid; >> +    cpumask_set_cpu(cpu, &hdr->cpu_mask); >> +} >> + >> +static void mpam_resctrl_online_domain_hdr(unsigned int cpu, >> +                       struct rdt_domain_hdr *hdr) >> +{ >> +    lockdep_assert_cpus_held(); >> + >> +    cpumask_set_cpu(cpu, &hdr->cpu_mask); >> +} >> + >> +/** >> + * mpam_resctrl_offline_domain_hdr() - Update the domain header to >> remove a CPU. >> + * @cpu:    The CPU to remove from the domain. >> + * @hdr:    The domain's header. >> + * >> + * Removes @cpu from the header mask. If this was the last CPU in the >> domain, >                                                  ^^^ >                                                  is > >> + * the domain header is removed from its parent list and true is >> returned, >> + * indicating the parent structure can be freed. >> + * If there are other CPUs in the domain, returns false. >> + */ >> +static bool mpam_resctrl_offline_domain_hdr(unsigned int cpu, >> +                        struct rdt_domain_hdr *hdr) >> +{ >> +    lockdep_assert_held(&domain_list_lock); >> + >> +    cpumask_clear_cpu(cpu, &hdr->cpu_mask); >> +    if (cpumask_empty(&hdr->cpu_mask)) { >> +        list_del_rcu(&hdr->list); >> +        synchronize_rcu(); >> +        return true; >> +    } >> + >> +    return false; >> +} >> + >> +static void mpam_resctrl_domain_insert(struct list_head *list, >> +                       struct rdt_domain_hdr *new) >> +{ >> +    struct rdt_domain_hdr *err; >> +    struct list_head *pos = NULL; >> + >> +    lockdep_assert_held(&domain_list_lock); >> + >> +    err = resctrl_find_domain(list, new->id, &pos); >> +    if (WARN_ON_ONCE(err)) >> +        return; >> + >> +    list_add_tail_rcu(&new->list, pos); >> +} >> + >> +static struct mpam_resctrl_dom * >> +mpam_resctrl_alloc_domain(unsigned int cpu, struct mpam_resctrl_res >> *res) >> +{ >> +    int err; >> +    struct mpam_resctrl_dom *dom; >> +    struct rdt_ctrl_domain *ctrl_d; >> +    struct mpam_class *class = res->class; >> +    struct mpam_component *comp_iter, *ctrl_comp; >> +    struct rdt_resource *r = &res->resctrl_res; >> + >> +    lockdep_assert_held(&domain_list_lock); >> + >> +    ctrl_comp = NULL; >> +    guard(srcu)(&mpam_srcu); >> +    list_for_each_entry_srcu(comp_iter, &class->components, class_list, >> +                 srcu_read_lock_held(&mpam_srcu)) { >> +        if (cpumask_test_cpu(cpu, &comp_iter->affinity)) { >> +            ctrl_comp = comp_iter; >> +            break; >> +        } >> +    } >> + >> +    /* class has no component for this CPU */ >> +    if (WARN_ON_ONCE(!ctrl_comp)) >> +        return ERR_PTR(-EINVAL); >> + >> +    dom = kzalloc_node(sizeof(*dom), GFP_KERNEL, cpu_to_node(cpu)); >> +    if (!dom) >> +        return ERR_PTR(-ENOMEM); >> + >> +    if (resctrl_arch_alloc_capable()) { >> +        dom->ctrl_comp = ctrl_comp; >> + >> +        ctrl_d = &dom->resctrl_ctrl_dom; >> +        mpam_resctrl_domain_hdr_init(cpu, ctrl_comp, r->rid, &ctrl_d- >> >hdr); >> +        ctrl_d->hdr.type = RESCTRL_CTRL_DOMAIN; >> +        err = resctrl_online_ctrl_domain(r, ctrl_d); >> +        if (err) >> +            goto free_domain; >> + >> +        mpam_resctrl_domain_insert(&r->ctrl_domains, &ctrl_d->hdr); >> +    } else { >> +        pr_debug("Skipped control domain online - no controls\n"); >> +    } >> +    return dom; >> + >> +offline_ctrl_domain: >> +    if (resctrl_arch_alloc_capable()) { >> +        mpam_resctrl_offline_domain_hdr(cpu, &ctrl_d->hdr); >> +        resctrl_offline_ctrl_domain(r, ctrl_d); >> +    } >> +free_domain: >> +    kfree(dom); >> +    dom = ERR_PTR(err); >> + >> +    return dom; >> +} >> + >> +static struct mpam_resctrl_dom * >> +mpam_resctrl_get_domain_from_cpu(int cpu, struct mpam_resctrl_res *res) >> +{ >> +    struct mpam_resctrl_dom *dom; >> +    struct rdt_resource *r = &res->resctrl_res; >> + >> +    lockdep_assert_cpus_held(); >> + >> +    list_for_each_entry_rcu(dom, &r->ctrl_domains, >> resctrl_ctrl_dom.hdr.list) { >> +        if (cpumask_test_cpu(cpu, &dom->ctrl_comp->affinity)) >> +            return dom; >> +    } >> + >> +    return NULL; >> +} >> + >> +int mpam_resctrl_online_cpu(unsigned int cpu) >> +{ >> +    struct mpam_resctrl_res *res; >> +    enum resctrl_res_level rid; >> + >> +    guard(mutex)(&domain_list_lock); >> +    for_each_mpam_resctrl_control(res, rid) { >> +        struct mpam_resctrl_dom *dom; >> + >> +        if (!res->class) >> +            continue;    // dummy_resource; >> + >> +        dom = mpam_resctrl_get_domain_from_cpu(cpu, res); >> +        if (!dom) { >> +            dom = mpam_resctrl_alloc_domain(cpu, res); >> +        } else { >> +            if (resctrl_arch_alloc_capable()) { >> +                struct rdt_ctrl_domain *ctrl_d = &dom->resctrl_ctrl_dom; >> + >> +                mpam_resctrl_online_domain_hdr(cpu, &ctrl_d->hdr); >> +            } >> +        } >> +        if (IS_ERR(dom)) >> +            return PTR_ERR(dom); >> +    } >> + >> +    resctrl_online_cpu(cpu); >> + >> +    return 0; >> +} >> + >> +void mpam_resctrl_offline_cpu(unsigned int cpu) >> +{ >> +    struct mpam_resctrl_res *res; >> +    enum resctrl_res_level rid; >> + >> +    resctrl_offline_cpu(cpu); >> + >> +    guard(mutex)(&domain_list_lock); >> +    for_each_mpam_resctrl_control(res, rid) { >> +        struct mpam_resctrl_dom *dom; >> +        struct rdt_ctrl_domain *ctrl_d; >> +        bool ctrl_dom_empty; >> + >> +        if (!res->class) >> +            continue;    // dummy resource >> + >> +        dom = mpam_resctrl_get_domain_from_cpu(cpu, res); >> +        if (WARN_ON_ONCE(!dom)) >> +            continue; >> + >> +        if (resctrl_arch_alloc_capable()) { >> +            ctrl_d = &dom->resctrl_ctrl_dom; >> +            ctrl_dom_empty = mpam_resctrl_offline_domain_hdr(cpu, >> &ctrl_d->hdr); >> +            if (ctrl_dom_empty) >> +                resctrl_offline_ctrl_domain(&res->resctrl_res, ctrl_d); >> +        } else { >> +            ctrl_dom_empty = true; >> +        } >> + >> +        if (ctrl_dom_empty) >> +            kfree(dom); >> +    } >> +} >> + >> +int mpam_resctrl_setup(void) >> +{ >> +    int err = 0; >> +    struct mpam_resctrl_res *res; >> +    enum resctrl_res_level rid; >> + >> +    cpus_read_lock(); >> +    for_each_mpam_resctrl_control(res, rid) { >> +        INIT_LIST_HEAD_RCU(&res->resctrl_res.ctrl_domains); >> +        res->resctrl_res.rid = rid; >> +    } >> + >> +    /* TODO: pick MPAM classes to map to resctrl resources */ >> + >> +    /* Initialise the resctrl structures from the classes */ >> +    for_each_mpam_resctrl_control(res, rid) { >> +        if (!res->class) >> +            continue;    // dummy resource >> + >> +        err = mpam_resctrl_control_init(res); >> +        if (err) { >> +            pr_debug("Failed to initialise rid %u\n", rid); >> +            break; >> +        } >> +    } >> +    cpus_read_unlock(); >> + >> +    if (err) { >> +        pr_debug("Internal error %d - resctrl not supported\n", err); >> +        return err; >> +    } >> + > > This pr_debug() could be dropped since @err is set to true only when > a error is returned from mpam_resctrl_control_init(), we already had > a pr_debug() for the reported error. Later in the series this can be an error from mpam_resctrl_monitor_init() which does also have an associated pr_debug() but to me it seems reasonable to have this extra message to make the severity clearer. Thanks, Ben