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[175.34.62.5]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-ba8f8d7eedcsm10930841a12.2.2025.11.09.14.59.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 09 Nov 2025 14:59:48 -0800 (PST) Message-ID: <07acf54a-231f-428d-ac94-f4f9ec95de21@redhat.com> Date: Mon, 10 Nov 2025 08:59:35 +1000 Precedence: bulk X-Mailing-List: linux-kernel@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: Ben Horgan , 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> Content-Language: en-US From: Gavin Shan In-Reply-To: <20251107123450.664001-24-ben.horgan@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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. > 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)' > > - 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)' > - 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 (?) > + 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