Message-ID: <690c1af39c9f7d4d9d5a1f2f84e89717bb756f23.1747349530.git.babu.moger@amd.com>
Date: Thu, 15 May 2025 17:51:58 -0500
From: Babu Moger <babu.moger@....com>
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Subject: [PATCH v13 13/27] x86/resctrl: Add the functionality to assign MBM events

The mbm_cntr_assign mode offers "num_mbm_cntrs" number of counters that
can be assigned to RMID, event pair and monitor the bandwidth as long
as it is assigned.

Add the functionality to allocate and assign a counter to am RMID, event
pair in the domain.

If all the counters are in use, kernel will log the error message "Unable
to allocate counter in domain" in /sys/fs/resctrl/info/last_cmd_status
when a new assignment is requested. Exit on the first failure when
assigning counters across all the domains.

Signed-off-by: Babu Moger <babu.moger@....com>
---
v13: Updated changelog.
     Changed resctrl_arch_config_cntr() to return void instead of int.
     Just passing evtid is to resctrl_alloc_config_cntr() and
     resctrl_assign_cntr_event(). Event configuration value can be easily
     obtained from mon_evt list.
     Introduced new function mbm_get_mon_event() to get event configuration value.
     Added prototype descriptions to mbm_cntr_get() and mbm_cntr_alloc().
     Resolved conflicts caused by the recent FS/ARCH code restructure.
     The files monitor.c/rdtgroup.c have been split between FS and ARCH directories.

v12: Fixed typo in the subjest line.
     Replaced several counters with "num_mbm_cntrs" counters.
     Changed the check in resctrl_alloc_config_cntr() to reduce the indentation.
     Fixed the handling error on first failure.
     Added domain id and event id on failure.
     Fixed the return error override.
     Added new parameter event configuration (evt_cfg) to get the event configuration
     from user space.

v11: Patch changed again quite a bit.
     Moved the functions to monitor.c.
     Renamed rdtgroup_assign_cntr_event() to resctrl_assign_cntr_event().
     Refactored the resctrl_assign_cntr_event().
     Added functionality to exit on the first error during assignment.
     Simplified mbm_cntr_free().
     Removed the function mbm_cntr_assigned(). Will be using mbm_cntr_get() to
     figure out if the counter is assigned or not.
     Updated commit message and code comments.

v10: Patch changed completely.
     Counters are managed at the domain based on the discussion.
     https://lore.kernel.org/lkml/CALPaoCj+zWq1vkHVbXYP0znJbe6Ke3PXPWjtri5AFgD9cQDCUg@mail.gmail.com/
     Reset non-architectural MBM state.
     Commit message update.

v9: Introduced new function resctrl_config_cntr to assign the counter, update
    the bitmap and reset the architectural state.
    Taken care of error handling(freeing the counter) when assignment fails.
    Moved mbm_cntr_assigned_to_domain here as it used in this patch.
    Minor text changes.

v8: Renamed rdtgroup_assign_cntr() to rdtgroup_assign_cntr_event().
    Added the code to return the error if rdtgroup_assign_cntr_event fails.
    Moved definition of MBM_EVENT_ARRAY_INDEX to resctrl/internal.h.
    Updated typo in the comments.

v7: New patch. Moved all the FS code here.
    Merged rdtgroup_assign_cntr and rdtgroup_alloc_cntr.
    Adde new #define MBM_EVENT_ARRAY_INDEX.
---
 fs/resctrl/internal.h |   3 +
 fs/resctrl/monitor.c  | 134 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 137 insertions(+)

diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index 0fae374559ba..ce4fcac91937 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -377,6 +377,9 @@ bool closid_allocated(unsigned int closid);
 
 int resctrl_find_cleanest_closid(void);
 
+int resctrl_assign_cntr_event(struct rdt_resource *r, struct rdt_mon_domain *d,
+			      struct rdtgroup *rdtgrp, enum resctrl_event_id evtid);
+
 #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
 int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);
 
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 8e403587a02f..d76fd0840946 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -934,3 +934,137 @@ void resctrl_mon_resource_exit(void)
 
 	dom_data_exit(r);
 }
+
+/*
+ * Configure the counter for the event, RMID pair for the domain. Reset the
+ * non-architectural state to clear all the event counters.
+ */
+static void resctrl_config_cntr(struct rdt_resource *r, struct rdt_mon_domain *d,
+				enum resctrl_event_id evtid, u32 rmid, u32 closid,
+				u32 cntr_id, u32 evt_cfg, bool assign)
+{
+	struct mbm_state *m;
+
+	resctrl_arch_config_cntr(r, d, evtid, rmid, closid, cntr_id, evt_cfg, assign);
+
+	m = get_mbm_state(d, closid, rmid, evtid);
+	if (m)
+		memset(m, 0, sizeof(struct mbm_state));
+}
+
+/*
+ * mbm_cntr_get() - Return the cntr_id for the matching evtid and rdtgrp in
+ *		    cntr_cfg array.
+ */
+static int mbm_cntr_get(struct rdt_resource *r, struct rdt_mon_domain *d,
+			struct rdtgroup *rdtgrp, enum resctrl_event_id evtid)
+{
+	int cntr_id;
+
+	for (cntr_id = 0; cntr_id < r->mon.num_mbm_cntrs; cntr_id++) {
+		if (d->cntr_cfg[cntr_id].rdtgrp == rdtgrp &&
+		    d->cntr_cfg[cntr_id].evtid == evtid)
+			return cntr_id;
+	}
+
+	return -ENOENT;
+}
+
+/*
+ * mbm_cntr_alloc() - Return the first free entry in cntr_cfg array.
+ */
+static int mbm_cntr_alloc(struct rdt_resource *r, struct rdt_mon_domain *d,
+			  struct rdtgroup *rdtgrp, enum resctrl_event_id evtid)
+{
+	int cntr_id;
+
+	for (cntr_id = 0; cntr_id < r->mon.num_mbm_cntrs; cntr_id++) {
+		if (!d->cntr_cfg[cntr_id].rdtgrp) {
+			d->cntr_cfg[cntr_id].rdtgrp = rdtgrp;
+			d->cntr_cfg[cntr_id].evtid = evtid;
+			return cntr_id;
+		}
+	}
+
+	return -ENOSPC;
+}
+
+/*
+ * mbm_get_mon_event() - Return the mon_evt entry for the matching evtid.
+ */
+static struct mon_evt *mbm_get_mon_event(struct rdt_resource *r,
+					 enum resctrl_event_id evtid)
+{
+	struct mon_evt *mevt;
+
+	list_for_each_entry(mevt, &r->mon.evt_list, list) {
+		if (mevt->evtid == evtid)
+			return mevt;
+	}
+
+	return NULL;
+}
+
+/*
+ * Allocate a fresh counter and configure the event if not assigned already.
+ */
+static int resctrl_alloc_config_cntr(struct rdt_resource *r, struct rdt_mon_domain *d,
+				     struct rdtgroup *rdtgrp, enum resctrl_event_id evtid)
+{
+	struct mon_evt *mevt;
+	int cntr_id;
+
+	/* No need to allocate a new counter if it is already assigned */
+	cntr_id = mbm_cntr_get(r, d, rdtgrp, evtid);
+	if (cntr_id >= 0)
+		goto cntr_configure;
+
+	cntr_id = mbm_cntr_alloc(r, d, rdtgrp, evtid);
+	if (cntr_id <  0) {
+		rdt_last_cmd_printf("Unable to allocate counter in domain %d\n",
+				    d->hdr.id);
+		return cntr_id;
+	}
+
+cntr_configure:
+	mevt = mbm_get_mon_event(r, evtid);
+	if (!mevt) {
+		rdt_last_cmd_printf("Invalid event id %d\n", evtid);
+		return -EINVAL;
+	}
+
+	/*
+	 * Skip reconfiguration if the event setup is current; otherwise,
+	 * update and apply the new configuration to the domain.
+	 */
+	if (mevt->evt_cfg != d->cntr_cfg[cntr_id].evt_cfg) {
+		d->cntr_cfg[cntr_id].evt_cfg = mevt->evt_cfg;
+		resctrl_config_cntr(r, d, evtid, rdtgrp->mon.rmid, rdtgrp->closid,
+				    cntr_id, mevt->evt_cfg, true);
+	}
+
+	return 0;
+}
+
+/*
+ * Assign a hardware counter to event @evtid of group @rdtgrp.
+ * Assign counters to all domains if @d is NULL; otherwise, assign the
+ * counter to the specified domain @d.
+ */
+int resctrl_assign_cntr_event(struct rdt_resource *r, struct rdt_mon_domain *d,
+			      struct rdtgroup *rdtgrp, enum resctrl_event_id evtid)
+{
+	int ret = 0;
+
+	if (!d) {
+		list_for_each_entry(d, &r->mon_domains, hdr.list) {
+			ret = resctrl_alloc_config_cntr(r, d, rdtgrp, evtid);
+			if (ret)
+				return ret;
+		}
+	} else {
+		ret = resctrl_alloc_config_cntr(r, d, rdtgrp, evtid);
+	}
+
+	return ret;
+}
-- 
2.34.1

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