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 38B47352932; Thu, 13 Nov 2025 17:15:02 +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=1763054106; cv=none; b=UOaa913ramRZt+zayngvlL/LBz+8O1hKShZ+cAVS+h7avdORpGuFi/A/g5i54J6Nv/qYiOlVLmLamysUP46njR8HgXubFy4ry8DtdH4+laFdaoN5/ROqIsFPEqNVoF1q/LSjN7/Pn+SsZC9MHugEMd/0Adty9nxHUOBQIZHQFuE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763054106; c=relaxed/simple; bh=yKvm6onMazwUEybFNBwsn5lbXMPfI5U2X5nOJb1ksR4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Ma/wJkV73i35FRiySLSlRHhEMNuJICFDdMc8QLUCV4+3eULFwIStHeus4GJu7536HcNbJTpqnJ9qWTIWTZ3/ANzA8gqdjS6+ACucuYipfmkqSRA0oeUY079LYlG28eiKc7oWy+p3Jb8XwjLwy1On4joH+AR8tfcRr0h0NfkAzSk= 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 C53EA12FC; Thu, 13 Nov 2025 09:14:54 -0800 (PST) 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 61BDB3F66E; Thu, 13 Nov 2025 09:14:57 -0800 (PST) Message-ID: Date: Thu, 13 Nov 2025 17:14:56 +0000 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 23/33] arm_mpam: Allow configuration to be applied and restored during cpu online To: Gavin Shan , 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, 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 References: <20251107123450.664001-1-ben.horgan@arm.com> <20251107123450.664001-24-ben.horgan@arm.com> <07acf54a-231f-428d-ac94-f4f9ec95de21@redhat.com> From: Ben Horgan Content-Language: en-US In-Reply-To: <07acf54a-231f-428d-ac94-f4f9ec95de21@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Gavin, On 11/9/25 22:59, Gavin Shan wrote: > Hi Ben > > On 11/7/25 10:34 PM, Ben Horgan wrote: >> From: James Morse >> >> When CPUs come online the MSC's original configuration should be >> restored. >> >> Add struct mpam_config to hold the configuration. This has a bitmap of >> features that were modified. Once the maximum partid is known, allocate >> a configuration array for each component, and reprogram each RIS >> configuration from this. >> >> CC: Dave Martin >> Signed-off-by: James Morse >> Cc: Shaopeng Tan (Fujitsu) tan.shaopeng@fujitsu.com >> Cc: Peter Newman peternewman@google.com >> Signed-off-by: Ben Horgan >> --- >> Changes since v3: >> Drop tags >> Fix component reset, otherwise cpbm wrong and controls not set. >> Add a cfg_lock to guard configuration of an msc >> --- >>   drivers/resctrl/mpam_devices.c  | 268 ++++++++++++++++++++++++++++++-- >>   drivers/resctrl/mpam_internal.h |  27 ++++ >>   2 files changed, 280 insertions(+), 15 deletions(-) >> > > With the following comments addressed: > > Reviewed-by: Gavin Shan > >> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/ >> mpam_devices.c >> index 3a0ad8d93fff..8b0944bdaf28 100644 >> --- a/drivers/resctrl/mpam_devices.c >> +++ b/drivers/resctrl/mpam_devices.c >> @@ -144,6 +144,16 @@ static void mpam_free_garbage(void) >>       } >>   } >>   +/* >> + * Once mpam is enabled, new requestors cannot further reduce the >> available >> + * partid. Assert that the size is fixed, and new requestors will be >> turned >> + * away. >> + */ >> +static void mpam_assert_partid_sizes_fixed(void) >> +{ >> +    WARN_ON_ONCE(!partid_max_published); >> +} >> + > > Would be worthy to be a online function. Assuming you mean 'inline'. I don't think it really matters but I'll leave it as is so that WARN_ON_ONCE() only ever gives one warning. > >>   static u32 __mpam_read_reg(struct mpam_msc *msc, u16 reg) >>   { >>       WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc- >> >accessibility)); >> @@ -343,6 +353,7 @@ mpam_component_alloc(struct mpam_class *class, int >> id) >>       return comp; >>   } >>   +static void __destroy_component_cfg(struct mpam_component *comp); >>   static void mpam_class_destroy(struct mpam_class *class); >>     static void mpam_component_destroy(struct mpam_component *comp) >> @@ -351,6 +362,8 @@ static void mpam_component_destroy(struct >> mpam_component *comp) >>         lockdep_assert_held(&mpam_list_lock); >>   +    __destroy_component_cfg(comp); >> + >>       list_del_rcu(&comp->class_list); >>       add_to_garbage(comp); >>   @@ -820,31 +833,59 @@ static void mpam_reset_msc_bitmap(struct >> mpam_msc *msc, u16 reg, u16 wd) >>       __mpam_write_reg(msc, reg, bm); >>   } >>   -static void mpam_reset_ris_partid(struct mpam_msc_ris *ris, u16 >> partid) >> +/* Called via IPI. Call while holding an SRCU reference */ >> +static void mpam_reprogram_ris_partid(struct mpam_msc_ris *ris, u16 >> partid, >> +                      struct mpam_config *cfg) >>   { >>       struct mpam_msc *msc = ris->vmsc->msc; >>       struct mpam_props *rprops = &ris->props; >>   -    WARN_ON_ONCE(!srcu_read_lock_held((&mpam_srcu))); >> - >>       mutex_lock(&msc->part_sel_lock); >>       __mpam_part_sel(ris->ris_idx, partid, msc); >>   -    if (mpam_has_feature(mpam_feat_cpor_part, rprops)) >> -        mpam_reset_msc_bitmap(msc, MPAMCFG_CPBM, rprops->cpbm_wd); >> +    if (mpam_has_feature(mpam_feat_cpor_part, rprops) && >> +        mpam_has_feature(mpam_feat_cpor_part, cfg)) { >> +        if (cfg->reset_cpbm) >> +            mpam_reset_msc_bitmap(msc, MPAMCFG_CPBM, >> +                          rprops->cpbm_wd); >> +        else >> +            mpam_write_partsel_reg(msc, CPBM, cfg->cpbm); >> +    } > > {} is needed by 'if (cfg->reset_cpbm)' Changed to be one line. > >>   -    if (mpam_has_feature(mpam_feat_mbw_part, rprops)) >> -        mpam_reset_msc_bitmap(msc, MPAMCFG_MBW_PBM, rprops- >> >mbw_pbm_bits); >> +    if (mpam_has_feature(mpam_feat_mbw_part, rprops) && >> +        mpam_has_feature(mpam_feat_mbw_part, cfg)) { >> +        if (cfg->reset_mbw_pbm) >> +            mpam_reset_msc_bitmap(msc, MPAMCFG_MBW_PBM, >> +                          rprops->mbw_pbm_bits); >> +        else >> +            mpam_write_partsel_reg(msc, MBW_PBM, cfg->mbw_pbm); >> +    } >>   > > { } is need by 'if (cfg->reset_mbw_pbm)' Changed to be one line. > >> -    if (mpam_has_feature(mpam_feat_mbw_min, rprops)) >> +    if (mpam_has_feature(mpam_feat_mbw_min, rprops) && >> +        mpam_has_feature(mpam_feat_mbw_min, cfg)) >>           mpam_write_partsel_reg(msc, MBW_MIN, 0); >>   -    if (mpam_has_feature(mpam_feat_mbw_max, rprops)) >> -        mpam_write_partsel_reg(msc, MBW_MAX, MPAMCFG_MBW_MAX_MAX); >> +    if (mpam_has_feature(mpam_feat_mbw_max, rprops) && >> +        mpam_has_feature(mpam_feat_mbw_max, cfg)) { >> +        if (cfg->reset_mbw_max) >> +            mpam_write_partsel_reg(msc, MBW_MAX, MPAMCFG_MBW_MAX_MAX); >> +        else >> +            mpam_write_partsel_reg(msc, MBW_MAX, cfg->mbw_max); >> +    } >>         mutex_unlock(&msc->part_sel_lock); >>   } >>   +static void mpam_init_reset_cfg(struct mpam_config *reset_cfg) >> +{ >> +    *reset_cfg = (struct mpam_config) { >> +        .reset_cpbm = true, >> +        .reset_mbw_pbm = true, >> +        .reset_mbw_max = true, >> +    }; >> +    bitmap_fill(reset_cfg->features, MPAM_FEATURE_LAST); >> +} >> + >>   /* >>    * Called via smp_call_on_cpu() to prevent migration, while still being >>    * pre-emptible. Caller must hold mpam_srcu. >> @@ -852,16 +893,19 @@ static void mpam_reset_ris_partid(struct >> mpam_msc_ris *ris, u16 partid) >>   static int mpam_reset_ris(void *arg) >>   { >>       u16 partid, partid_max; >> +    struct mpam_config reset_cfg; >>       struct mpam_msc_ris *ris = arg; >>         if (ris->in_reset_state) >>           return 0; >>   +    mpam_init_reset_cfg(&reset_cfg); >> + >>       spin_lock(&partid_max_lock); >>       partid_max = mpam_partid_max; >>       spin_unlock(&partid_max_lock); >>       for (partid = 0; partid <= partid_max; partid++) >> -        mpam_reset_ris_partid(ris, partid); >> +        mpam_reprogram_ris_partid(ris, partid, &reset_cfg); >>         return 0; >>   } >> @@ -894,6 +938,7 @@ static void mpam_reset_msc(struct mpam_msc *msc, >> bool online) >>   { >>       struct mpam_msc_ris *ris; >>   +    mutex_lock(&msc->cfg_lock); >>       list_for_each_entry_srcu(ris, &msc->ris, msc_list, >> srcu_read_lock_held(&mpam_srcu)) { >>           mpam_touch_msc(msc, &mpam_reset_ris, ris); >>   @@ -903,6 +948,61 @@ static void mpam_reset_msc(struct mpam_msc >> *msc, bool online) >>            */ >>           ris->in_reset_state = online; >>       } >> +    mutex_unlock(&msc->cfg_lock); >> +} >> + >> +struct mpam_write_config_arg { >> +    struct mpam_msc_ris *ris; >> +    struct mpam_component *comp; >> +    u16 partid; >> +}; >> + >> +static int __write_config(void *arg) >> +{ >> +    struct mpam_write_config_arg *c = arg; >> + >> +    mpam_reprogram_ris_partid(c->ris, c->partid, &c->comp->cfg[c- >> >partid]); >> + >> +    return 0; >> +} >> + >> +static void mpam_reprogram_msc(struct mpam_msc *msc) >> +{ >> +    u16 partid; >> +    bool reset; >> +    struct mpam_config *cfg; >> +    struct mpam_msc_ris *ris; >> +    struct mpam_write_config_arg arg; >> + >> +    /* >> +     * No lock for mpam_partid_max as partid_max_published has been >> +     * set by mpam_enabled(), so the values can no longer change. >> +     */ >> +    mpam_assert_partid_sizes_fixed(); >> + >> +    mutex_lock(&msc->cfg_lock); >> +    list_for_each_entry_srcu(ris, &msc->ris, msc_list, >> +                 srcu_read_lock_held(&mpam_srcu)) { >> +        if (!mpam_is_enabled() && !ris->in_reset_state) { >> +            mpam_touch_msc(msc, &mpam_reset_ris, ris); >> +            ris->in_reset_state = true; >> +            continue; >> +        } >> + >> +        arg.comp = ris->vmsc->comp; >> +        arg.ris = ris; >> +        reset = true; >> +        for (partid = 0; partid <= mpam_partid_max; partid++) { >> +            cfg = &ris->vmsc->comp->cfg[partid]; >> +            if (!bitmap_empty(cfg->features, MPAM_FEATURE_LAST)) >> +                reset = false; >> + > > s/!bitmap_empty()/!bitmap_full (?) This is checking if there is any work for the configuration to do and so checking if there are any feature bits set, !bitmap_empty(), is the correct thing to do. > >> +            arg.partid = partid; >> +            mpam_touch_msc(msc, __write_config, &arg); >> +        } >> +        ris->in_reset_state = reset; >> +    } >> +    mutex_unlock(&msc->cfg_lock); >>   } >>     static void _enable_percpu_irq(void *_irq) >> @@ -926,7 +1026,7 @@ static int mpam_cpu_online(unsigned int cpu) >>               _enable_percpu_irq(&msc->reenable_error_ppi); >>             if (atomic_fetch_inc(&msc->online_refs) == 0) >> -            mpam_reset_msc(msc, true); >> +            mpam_reprogram_msc(msc); >>       } >>         return 0; >> @@ -1125,6 +1225,9 @@ static struct mpam_msc >> *do_mpam_msc_drv_probe(struct platform_device *pdev) >>       if (err) >>           return ERR_PTR(err); >>       err = devm_mutex_init(dev, &msc->error_irq_lock); >> +    if (err) >> +        return ERR_PTR(err); >> +    err = devm_mutex_init(dev, &msc->cfg_lock); >>       if (err) >>           return ERR_PTR(err); >>       mpam_mon_sel_lock_init(msc); >> @@ -1585,6 +1688,70 @@ static void mpam_unregister_irqs(void) >>       } >>   } >>   +static void __destroy_component_cfg(struct mpam_component *comp) >> +{ >> +    add_to_garbage(comp->cfg); >> +} >> + >> +static void mpam_reset_component_cfg(struct mpam_component *comp) >> +{ >> +    int i; >> +    struct mpam_props *cprops = &comp->class->props; >> + >> +    mpam_assert_partid_sizes_fixed(); >> + >> +    if (!comp->cfg) >> +        return; >> + >> +    for (i = 0; i <= mpam_partid_max; i++) { >> +        comp->cfg[i] = (struct mpam_config) {}; >> +        bitmap_fill(comp->cfg[i].features, MPAM_FEATURE_LAST); >> +        bitmap_set((unsigned long *)&comp->cfg[i].cpbm, 0, cprops- >> >cpbm_wd); >> +        bitmap_set((unsigned long *)&comp->cfg[i].mbw_pbm, 0, cprops- >> >mbw_pbm_bits); >> +        bitmap_set((unsigned long *)&comp->cfg[i].mbw_max, 16 - >> cprops->bwa_wd, cprops->bwa_wd); >> +    } >> +} >> + >> +static int __allocate_component_cfg(struct mpam_component *comp) >> +{ >> +    mpam_assert_partid_sizes_fixed(); >> + >> +    if (comp->cfg) >> +        return 0; >> + >> +    comp->cfg = kcalloc(mpam_partid_max + 1, sizeof(*comp->cfg), >> GFP_KERNEL); >> +    if (!comp->cfg) >> +        return -ENOMEM; >> + >> +    /* >> +     * The array is free()d in one go, so only cfg[0]'s structure needs >> +     * to be initialised. >> +     */ >> +    init_garbage(&comp->cfg[0].garbage); >> + >> +    mpam_reset_component_cfg(comp); >> + >> +    return 0; >> +} >> + >> +static int mpam_allocate_config(void) >> +{ >> +    struct mpam_class *class; >> +    struct mpam_component *comp; >> + >> +    lockdep_assert_held(&mpam_list_lock); >> + >> +    list_for_each_entry(class, &mpam_classes, classes_list) { >> +        list_for_each_entry(comp, &class->components, class_list) { >> +            int err = __allocate_component_cfg(comp); >> +            if (err) >> +                return err; >> +        } >> +    } >> + >> +    return 0; >> +} >> + >>   static void mpam_enable_once(void) >>   { >>       int err; >> @@ -1604,15 +1771,25 @@ static void mpam_enable_once(void) >>        */ >>       cpus_read_lock(); >>       mutex_lock(&mpam_list_lock); >> -    mpam_enable_merge_features(&mpam_classes); >> +    do { >> +        mpam_enable_merge_features(&mpam_classes); >>   -    err = mpam_register_irqs(); >> +        err = mpam_register_irqs(); >> +        if (err) { >> +            pr_warn("Failed to register irqs: %d\n", err); >> +            break; >> +        } >>   +        err = mpam_allocate_config(); >> +        if (err) { >> +            pr_err("Failed to allocate configuration arrays.\n"); >> +            break; >> +        } >> +    } while (0); >>       mutex_unlock(&mpam_list_lock); >>       cpus_read_unlock(); >>         if (err) { >> -        pr_warn("Failed to register irqs: %d\n", err); >>           mpam_disable_reason = "Failed to enable."; >>           schedule_work(&mpam_broken_work); >>           return; >> @@ -1632,6 +1809,9 @@ static void mpam_reset_component_locked(struct >> mpam_component *comp) >>       struct mpam_vmsc *vmsc; >>         lockdep_assert_cpus_held(); >> +    mpam_assert_partid_sizes_fixed(); >> + >> +    mpam_reset_component_cfg(comp); >>         guard(srcu)(&mpam_srcu); >>       list_for_each_entry_srcu(vmsc, &comp->vmsc, comp_list, >> @@ -1732,6 +1912,64 @@ void mpam_enable(struct work_struct *work) >>           mpam_enable_once(); >>   } >>   +#define maybe_update_config(cfg, feature, newcfg, member, changes) >> do { \ >> +    if (mpam_has_feature(feature, newcfg) &&            \ >> +        (newcfg)->member != (cfg)->member) {            \ >> +        (cfg)->member = (newcfg)->member;            \ >> +        mpam_set_feature(feature, cfg);                \ >> +                                    \ >> +        (changes) = true;                    \ >> +    }                                \ >> +} while (0) >> + >> +static bool mpam_update_config(struct mpam_config *cfg, >> +                   const struct mpam_config *newcfg) >> +{ >> +    bool has_changes = false; >> + >> +    maybe_update_config(cfg, mpam_feat_cpor_part, newcfg, cpbm, >> has_changes); >> +    maybe_update_config(cfg, mpam_feat_mbw_part, newcfg, mbw_pbm, >> has_changes); >> +    maybe_update_config(cfg, mpam_feat_mbw_max, newcfg, mbw_max, >> has_changes); >> + >> +    return has_changes; >> +} >> + >> +int mpam_apply_config(struct mpam_component *comp, u16 partid, >> +              struct mpam_config *cfg) >> +{ >> +    struct mpam_write_config_arg arg; >> +    struct mpam_msc_ris *ris; >> +    struct mpam_vmsc *vmsc; >> +    struct mpam_msc *msc; >> + >> +    lockdep_assert_cpus_held(); >> + >> +    /* Don't pass in the current config! */ >> +    WARN_ON_ONCE(&comp->cfg[partid] == cfg); >> + >> +    if (!mpam_update_config(&comp->cfg[partid], cfg)) >> +        return 0; >> + >> +    arg.comp = comp; >> +    arg.partid = partid; >> + >> +    guard(srcu)(&mpam_srcu); >> +    list_for_each_entry_srcu(vmsc, &comp->vmsc, comp_list, >> +                 srcu_read_lock_held(&mpam_srcu)) { >> +        msc = vmsc->msc; >> + >> +        mutex_lock(&msc->cfg_lock); >> +        list_for_each_entry_srcu(ris, &vmsc->ris, vmsc_list, >> +                     srcu_read_lock_held(&mpam_srcu)) { >> +            arg.ris = ris; >> +            mpam_touch_msc(msc, __write_config, &arg); >> +        } >> +        mutex_unlock(&msc->cfg_lock); >> +    } >> + >> +    return 0; >> +} >> + >>   static int __init mpam_msc_driver_init(void) >>   { >>       if (!system_supports_mpam()) >> diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/ >> mpam_internal.h >> index c6937161877a..842d32f148b5 100644 >> --- a/drivers/resctrl/mpam_internal.h >> +++ b/drivers/resctrl/mpam_internal.h >> @@ -91,6 +91,9 @@ struct mpam_msc { >>        */ >>       struct mutex        part_sel_lock; >>   +    /* cfg_lock protects the msc configuration. */ >> +    struct mutex        cfg_lock; >> + >>       /* >>        * mon_sel_lock protects access to the MSC hardware registers >> that are >>        * affected by MPAMCFG_MON_SEL, and the mbwu_state. >> @@ -180,6 +183,21 @@ struct mpam_class { >>       struct mpam_garbage    garbage; >>   }; >>   +struct mpam_config { >> +    /* Which configuration values are valid. */ >> +    DECLARE_BITMAP(features, MPAM_FEATURE_LAST); >> + >> +    u32    cpbm; >> +    u32    mbw_pbm; >> +    u16    mbw_max; >> + >> +    bool    reset_cpbm; >> +    bool    reset_mbw_pbm; >> +    bool    reset_mbw_max; >> + >> +    struct mpam_garbage    garbage; >> +}; >> + >>   struct mpam_component { >>       u32            comp_id; >>   @@ -188,6 +206,12 @@ struct mpam_component { >>         cpumask_t        affinity; >>   +    /* >> +     * Array of configuration values, indexed by partid. >> +     * Read from cpuhp callbacks, hold the cpuhp lock when writing. >> +     */ >> +    struct mpam_config    *cfg; >> + >>       /* member of mpam_class:components */ >>       struct list_head    class_list; >>   @@ -247,6 +271,9 @@ extern u8 mpam_pmg_max; >>   void mpam_enable(struct work_struct *work); >>   void mpam_disable(struct work_struct *work); >>   +int mpam_apply_config(struct mpam_component *comp, u16 partid, >> +              struct mpam_config *cfg); >> + >>   int mpam_get_cpumask_from_cache_id(unsigned long cache_id, u32 >> cache_level, >>                      cpumask_t *affinity); >>   > > Thanks, > Gavin > Thanks, Ben