]> git.ipfire.org Git - thirdparty/linux.git/commitdiff
arm_mpam: Allow configuration to be applied and restored during cpu online
authorJames Morse <james.morse@arm.com>
Wed, 19 Nov 2025 12:22:53 +0000 (12:22 +0000)
committerCatalin Marinas <catalin.marinas@arm.com>
Wed, 19 Nov 2025 18:34:22 +0000 (18:34 +0000)
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 <Dave.Martin@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Cc: Fujitsu Fujitsu <Shaopeng Tan tan.shaopeng@fujitsu.com>
Cc: Peter Newman peternewman@google.com
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com>
Tested-by: Gavin Shan <gshan@redhat.com>
Tested-by: Zeng Heng <zengheng4@huawei.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
drivers/resctrl/mpam_devices.c
drivers/resctrl/mpam_internal.h

index c126a95490f16bb3f4c451359c8bf9efab705b10..6dbd378acdcf332048962e2eaca2625737abc42f 100644 (file)
@@ -145,6 +145,16 @@ 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);
+}
+
 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;
 }
 
+static void __destroy_component_cfg(struct mpam_component *comp);
+
 static void mpam_component_destroy(struct mpam_component *comp)
 {
        struct mpam_class *class = comp->class;
 
        lockdep_assert_held(&mpam_list_lock);
 
+       __destroy_component_cfg(comp);
+
        list_del_rcu(&comp->class_list);
        add_to_garbage(comp);
 
@@ -819,31 +833,57 @@ 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);
+       }
 
-       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);
+       }
 
-       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.
@@ -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 = 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;
 }
@@ -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);
 }
 
-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 = 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();
 
-       list_for_each_entry_srcu(ris, &msc->ris, msc_list, srcu_read_lock_held(&mpam_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 = true;
+                       continue;
+               }
 
-               /*
-                * 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 = online;
+               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;
+
+                       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)
@@ -925,7 +1007,7 @@ 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;
@@ -980,8 +1062,22 @@ static int mpam_cpu_offline(unsigned int cpu)
                if (msc->reenable_error_ppi)
                        disable_percpu_irq(msc->reenable_error_ppi);
 
-               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 = false;
+                       }
+                       mutex_unlock(&msc->cfg_lock);
+               }
        }
 
        return 0;
@@ -1121,6 +1217,11 @@ static struct mpam_msc *do_mpam_msc_drv_probe(struct platform_device *pdev)
        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);
        msc->id = pdev->id;
        msc->pdev = pdev;
@@ -1581,6 +1682,72 @@ 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) {};
+               if (cprops->cpbm_wd)
+                       comp->cfg[i].cpbm = GENMASK(cprops->cpbm_wd - 1, 0);
+               if (cprops->mbw_pbm_bits)
+                       comp->cfg[i].mbw_pbm = GENMASK(cprops->mbw_pbm_bits - 1, 0);
+               if (cprops->bwa_wd)
+                       comp->cfg[i].mbw_max = 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 = 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;
@@ -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);
 
-       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;
@@ -1628,6 +1805,9 @@ 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,
@@ -1728,6 +1908,64 @@ 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())
index 93a629f6e15a79f8ae72c8a53fab84be4532543a..b8fdbd7ab7a5537b016aac12dfcf9c3d86689c32 100644 (file)
@@ -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.
@@ -182,6 +185,21 @@ 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;
 
@@ -190,6 +208,12 @@ 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;
 
@@ -249,6 +273,9 @@ 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);