arm_mpam: Add helper to reset saved mbwu state

resctrl expects to reset the bandwidth counters when the filesystem
is mounted.

To allow this, add a helper that clears the saved mbwu state. Instead
of cross calling to each CPU that can access the component MSC to
write to the counter, set a flag that causes it to be zero'd on the
the next read. This is easily done by forcing a configuration update.

Signed-off-by: James Morse <james.morse@arm.com>
Cc: Peter Newman <peternewman@google.com>
Reviewed-by: Fenghua Yu <fenghuay@nvdia.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-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>

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 0fb08222b91d03904bb7b6f97ea0750aaf2ac74f..b4aa817994295855bf5b9ed83cf2ce3974670f5a 100644 (file)
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -1075,6 +1075,7 @@ static void __ris_msmon_read(void *arg)
        bool overflow;
        struct mon_read *m = arg;
        struct mon_cfg *ctx = m->ctx;
+       bool reset_on_next_read = false;
        struct mpam_msc_ris *ris = m->ris;
        struct msmon_mbwu_state *mbwu_state;
        struct mpam_props *rprops = &ris->props;
@@ -1089,6 +1090,20 @@ static void __ris_msmon_read(void *arg)
                  FIELD_PREP(MSMON_CFG_MON_SEL_RIS, ris->ris_idx);
        mpam_write_monsel_reg(msc, CFG_MON_SEL, mon_sel);
 
+       switch (m->type) {
+       case mpam_feat_msmon_mbwu_31counter:
+       case mpam_feat_msmon_mbwu_44counter:
+       case mpam_feat_msmon_mbwu_63counter:
+               mbwu_state = &ris->mbwu_state[ctx->mon];
+               if (mbwu_state) {
+                       reset_on_next_read = mbwu_state->reset_on_next_read;
+                       mbwu_state->reset_on_next_read = false;
+               }
+               break;
+       default:
+               break;
+       }
+
        /*
         * Read the existing configuration to avoid re-writing the same values.
         * This saves waiting for 'nrdy' on subsequent reads.
@@ -1106,7 +1121,7 @@ static void __ris_msmon_read(void *arg)
        config_mismatch = cur_flt != flt_val ||
                          cur_ctl != (ctl_val | MSMON_CFG_x_CTL_EN);
 
-       if (config_mismatch) {
+       if (config_mismatch || reset_on_next_read) {
                write_msmon_ctl_flt_vals(m, ctl_val, flt_val);
                overflow = false;
        } else if (overflow) {
@@ -1263,6 +1278,37 @@ int mpam_msmon_read(struct mpam_component *comp, struct mon_cfg *ctx,
        return err;
 }
 
+void mpam_msmon_reset_mbwu(struct mpam_component *comp, struct mon_cfg *ctx)
+{
+       struct mpam_msc *msc;
+       struct mpam_vmsc *vmsc;
+       struct mpam_msc_ris *ris;
+
+       if (!mpam_is_enabled())
+               return;
+
+       guard(srcu)(&mpam_srcu);
+       list_for_each_entry_srcu(vmsc, &comp->vmsc, comp_list,
+                                srcu_read_lock_held(&mpam_srcu)) {
+               if (!mpam_has_feature(mpam_feat_msmon_mbwu, &vmsc->props))
+                       continue;
+
+               msc = vmsc->msc;
+               list_for_each_entry_srcu(ris, &vmsc->ris, vmsc_list,
+                                        srcu_read_lock_held(&mpam_srcu)) {
+                       if (!mpam_has_feature(mpam_feat_msmon_mbwu, &ris->props))
+                               continue;
+
+                       if (WARN_ON_ONCE(!mpam_mon_sel_lock(msc)))
+                               continue;
+
+                       ris->mbwu_state[ctx->mon].correction = 0;
+                       ris->mbwu_state[ctx->mon].reset_on_next_read = true;
+                       mpam_mon_sel_unlock(msc);
+               }
+       }
+}
+
 static void mpam_reset_msc_bitmap(struct mpam_msc *msc, u16 reg, u16 wd)
 {
        u32 num_words, msb;

diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
index 693a315c47107069f4af9bdd6f98254320011146..18d53c07b3d7a630a02f6abe5d4f468af770c1b7 100644 (file)
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -211,6 +211,7 @@ struct mon_cfg {
 /* Changes to msmon_mbwu_state are protected by the msc's mon_sel_lock. */
 struct msmon_mbwu_state {
        bool            enabled;
+       bool            reset_on_next_read;
        struct mon_cfg  cfg;
 
        /*
@@ -370,6 +371,7 @@ int mpam_apply_config(struct mpam_component *comp, u16 partid,
 
 int mpam_msmon_read(struct mpam_component *comp, struct mon_cfg *ctx,
                    enum mpam_device_features, u64 *val);
+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);