From nobody Tue Dec 2 02:32:19 2025 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5E327359FBB; Wed, 19 Nov 2025 12:25:35 +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=1763555137; cv=none; b=eP0PjexJF9tmdGou9sz2oeftBp9cZfrNJRfitVAUop2TIOs3LTt7l4Q6RTZqzGHoyg2li49p7RSPShayzmRH4mTPbcoDXvKcQXmuxHgTJy6ZFl2xwuFiAKH+ZTqQQS5MNUo79uDYoQLNFqXyhLqNiYfckZylIfiE+yi//RIPepY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763555137; c=relaxed/simple; bh=afi24150EAmwNKAXRk7k3pDyD64akJMEJw8V1a0rUrc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fgbTK6AKTZAHNf/EOONUQX8bnO2sy1+l8yR3Pr8j+sw60xsOIB7Mg5TAW2aWJZUexH1SCgZJ34bOF9otTQXRHGrnh0O9s5YyAHWTSCrW/vxm1Lf6LIwqizNnGcWI9a6mH+fMbpoECt8IzJ6RsRASqHLt8/6e1uHTPFTLXl6Dn0U= 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 66D5BFEC; Wed, 19 Nov 2025 04:25:27 -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 A6DDC3F740; Wed, 19 Nov 2025 04:25:29 -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, Dave Martin , Shaopeng Tan , Zeng Heng , Ben Horgan Subject: [PATCH v6 23/34] arm_mpam: Allow configuration to be applied and restored during cpu online Date: Wed, 19 Nov 2025 12:22:53 +0000 Message-ID: <20251119122305.302149-24-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 When CPUs come online the MSC's original configuration should be restored. Add struct mpam_config to hold the configuration. For each component, this has a bitmap of features that have been changed from the reset values. The mpam_config is also used on RIS reset where all bits are set to ensure all features are reset. 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 Reviewed-by: Gavin Shan Reviewed-by: Shaopeng Tan Reviewed-by: Jonathan Cameron Reviewed-by: Fenghua Yu Tested-by: Carl Worth Tested-by: Gavin Shan Tested-by: Zeng Heng Tested-by: Shaopeng Tan Tested-by: Hanjun Guo Signed-off-by: Ben Horgan --- Changes since v4: Jonathan: Use GENMASK instead of bitmap_set() blank lines clarify commit message Gavin: if formatting 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 | 288 +++++++++++++++++++++++++++++--- drivers/resctrl/mpam_internal.h | 27 +++ 2 files changed, 290 insertions(+), 25 deletions(-) diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index c126a95490f1..6dbd378acdcf 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -145,6 +145,16 @@ static void mpam_free_garbage(void) } } =20 +/* + * 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); +} + static u32 __mpam_read_reg(struct mpam_msc *msc, u16 reg) { WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility)); @@ -338,12 +348,16 @@ mpam_component_alloc(struct mpam_class *class, int id) return comp; } =20 +static void __destroy_component_cfg(struct mpam_component *comp); + static void mpam_component_destroy(struct mpam_component *comp) { struct mpam_class *class =3D comp->class; =20 lockdep_assert_held(&mpam_list_lock); =20 + __destroy_component_cfg(comp); + list_del_rcu(&comp->class_list); add_to_garbage(comp); =20 @@ -819,31 +833,57 @@ static void mpam_reset_msc_bitmap(struct mpam_msc *ms= c, u16 reg, u16 wd) __mpam_write_reg(msc, reg, bm); } =20 -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 =3D ris->vmsc->msc; struct mpam_props *rprops =3D &ris->props; =20 - WARN_ON_ONCE(!srcu_read_lock_held((&mpam_srcu))); - mutex_lock(&msc->part_sel_lock); __mpam_part_sel(ris->ris_idx, partid, msc); =20 - 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); + } =20 - 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); + } =20 - 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); =20 - 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); + } =20 mutex_unlock(&msc->part_sel_lock); } =20 +static void mpam_init_reset_cfg(struct mpam_config *reset_cfg) +{ + *reset_cfg =3D (struct mpam_config) { + .reset_cpbm =3D true, + .reset_mbw_pbm =3D true, + .reset_mbw_max =3D 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. @@ -851,16 +891,19 @@ 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 =3D arg; =20 if (ris->in_reset_state) return 0; =20 + mpam_init_reset_cfg(&reset_cfg); + spin_lock(&partid_max_lock); partid_max =3D mpam_partid_max; spin_unlock(&partid_max_lock); for (partid =3D 0; partid <=3D partid_max; partid++) - mpam_reset_ris_partid(ris, partid); + mpam_reprogram_ris_partid(ris, partid, &reset_cfg); =20 return 0; } @@ -889,19 +932,58 @@ static int mpam_touch_msc(struct mpam_msc *msc, int (= *fn)(void *a), void *arg) return smp_call_on_cpu(mpam_get_msc_preferred_cpu(msc), fn, arg, true); } =20 -static void mpam_reset_msc(struct mpam_msc *msc, bool online) +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 =3D 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(); =20 - list_for_each_entry_srcu(ris, &msc->ris, msc_list, srcu_read_lock_held(&m= pam_srcu)) { - mpam_touch_msc(msc, &mpam_reset_ris, ris); + 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 =3D true; + continue; + } =20 - /* - * Set in_reset_state when coming online. The reset state - * for non-zero partid may be lost while the CPUs are offline. - */ - ris->in_reset_state =3D online; + arg.comp =3D ris->vmsc->comp; + arg.ris =3D ris; + reset =3D true; + for (partid =3D 0; partid <=3D mpam_partid_max; partid++) { + cfg =3D &ris->vmsc->comp->cfg[partid]; + if (!bitmap_empty(cfg->features, MPAM_FEATURE_LAST)) + reset =3D false; + + arg.partid =3D partid; + mpam_touch_msc(msc, __write_config, &arg); + } + ris->in_reset_state =3D reset; } + mutex_unlock(&msc->cfg_lock); } =20 static void _enable_percpu_irq(void *_irq) @@ -925,7 +1007,7 @@ static int mpam_cpu_online(unsigned int cpu) _enable_percpu_irq(&msc->reenable_error_ppi); =20 if (atomic_fetch_inc(&msc->online_refs) =3D=3D 0) - mpam_reset_msc(msc, true); + mpam_reprogram_msc(msc); } =20 return 0; @@ -980,8 +1062,22 @@ static int mpam_cpu_offline(unsigned int cpu) if (msc->reenable_error_ppi) disable_percpu_irq(msc->reenable_error_ppi); =20 - if (atomic_dec_and_test(&msc->online_refs)) - mpam_reset_msc(msc, false); + if (atomic_dec_and_test(&msc->online_refs)) { + 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); + + /* + * The reset state for non-zero partid may be + * lost while the CPUs are offline. + */ + ris->in_reset_state =3D false; + } + mutex_unlock(&msc->cfg_lock); + } } =20 return 0; @@ -1121,6 +1217,11 @@ static struct mpam_msc *do_mpam_msc_drv_probe(struct= platform_device *pdev) err =3D devm_mutex_init(dev, &msc->error_irq_lock); if (err) return ERR_PTR(err); + + err =3D devm_mutex_init(dev, &msc->cfg_lock); + if (err) + return ERR_PTR(err); + mpam_mon_sel_lock_init(msc); msc->id =3D pdev->id; msc->pdev =3D pdev; @@ -1581,6 +1682,72 @@ static void mpam_unregister_irqs(void) } } =20 +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 =3D &comp->class->props; + + mpam_assert_partid_sizes_fixed(); + + if (!comp->cfg) + return; + + for (i =3D 0; i <=3D mpam_partid_max; i++) { + comp->cfg[i] =3D (struct mpam_config) {}; + if (cprops->cpbm_wd) + comp->cfg[i].cpbm =3D GENMASK(cprops->cpbm_wd - 1, 0); + if (cprops->mbw_pbm_bits) + comp->cfg[i].mbw_pbm =3D GENMASK(cprops->mbw_pbm_bits - 1, 0); + if (cprops->bwa_wd) + comp->cfg[i].mbw_max =3D GENMASK(15, 16 - cprops->bwa_wd); + } +} + +static int __allocate_component_cfg(struct mpam_component *comp) +{ + mpam_assert_partid_sizes_fixed(); + + if (comp->cfg) + return 0; + + comp->cfg =3D 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 =3D __allocate_component_cfg(comp); + if (err) + return err; + } + } + + return 0; +} + static void mpam_enable_once(void) { int err; @@ -1600,15 +1767,25 @@ 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); =20 - err =3D mpam_register_irqs(); + err =3D mpam_register_irqs(); + if (err) { + pr_warn("Failed to register irqs: %d\n", err); + break; + } =20 + err =3D mpam_allocate_config(); + if (err) { + pr_err("Failed to allocate configuration arrays.\n"); + break; + } + } while (0); mutex_unlock(&mpam_list_lock); cpus_read_unlock(); =20 if (err) { - pr_warn("Failed to register irqs: %d\n", err); mpam_disable_reason =3D "Failed to enable."; schedule_work(&mpam_broken_work); return; @@ -1628,6 +1805,9 @@ static void mpam_reset_component_locked(struct mpam_c= omponent *comp) struct mpam_vmsc *vmsc; =20 lockdep_assert_cpus_held(); + mpam_assert_partid_sizes_fixed(); + + mpam_reset_component_cfg(comp); =20 guard(srcu)(&mpam_srcu); list_for_each_entry_srcu(vmsc, &comp->vmsc, comp_list, @@ -1728,6 +1908,64 @@ void mpam_enable(struct work_struct *work) mpam_enable_once(); } =20 +#define maybe_update_config(cfg, feature, newcfg, member, changes) do { \ + if (mpam_has_feature(feature, newcfg) && \ + (newcfg)->member !=3D (cfg)->member) { \ + (cfg)->member =3D (newcfg)->member; \ + mpam_set_feature(feature, cfg); \ + \ + (changes) =3D true; \ + } \ +} while (0) + +static bool mpam_update_config(struct mpam_config *cfg, + const struct mpam_config *newcfg) +{ + bool has_changes =3D 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] =3D=3D cfg); + + if (!mpam_update_config(&comp->cfg[partid], cfg)) + return 0; + + arg.comp =3D comp; + arg.partid =3D partid; + + guard(srcu)(&mpam_srcu); + list_for_each_entry_srcu(vmsc, &comp->vmsc, comp_list, + srcu_read_lock_held(&mpam_srcu)) { + msc =3D 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 =3D 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_interna= l.h index 93a629f6e15a..b8fdbd7ab7a5 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; =20 + /* 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. @@ -182,6 +185,21 @@ struct mpam_class { struct mpam_garbage garbage; }; =20 +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; =20 @@ -190,6 +208,12 @@ struct mpam_component { =20 cpumask_t affinity; =20 + /* + * 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; =20 @@ -249,6 +273,9 @@ extern u8 mpam_pmg_max; void mpam_enable(struct work_struct *work); void mpam_disable(struct work_struct *work); =20 +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); =20 --=20 2.43.0