[PATCH RFC v1 1/6] resctrl: wire MB_MAXHLM schemata parsing and group setup

[Fenghua Yu]

The hard-limit control is a 0/1 value on the MBA resource, not a
separate schemata resource. Parse MB_MAXHLM in the bandwidth parser,
reject values other than 0 and 1, and initialize new groups with the
hard limit off.

Signed-off-by: Fenghua Yu <fenghuay@xxxxxxxxxx>
---
 fs/resctrl/ctrlmondata.c | 35 +++++++++++++++++++++++++++++++++++
 fs/resctrl/rdtgroup.c    | 17 +++++++++++++++++
 include/linux/resctrl.h  |  8 +++++++-
 3 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index 77a2f2e877a6..9111b0130783 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -62,6 +62,29 @@ static struct resctrl_ctrl_priv resctrl_ctrl_priv_all[] = {
 	},
 };
 
+static bool mb_maxhlm_validate(char *buf, u32 *data, struct rdt_resource *r,
+			       struct resctrl_ctrl *ctrl)
+{
+	int ret;
+	u32 mb_maxhlm;
+
+	ret = kstrtou32(buf, 10, &mb_maxhlm);
+	if (ret) {
+		rdt_last_cmd_printf("Invalid MB_MAXHLM value %s\n", buf);
+		return false;
+	}
+
+	if (mb_maxhlm != 0 && mb_maxhlm != 1) {
+		rdt_last_cmd_printf("MB_MAXHLM value %u isn't 0/1\n",
+				    mb_maxhlm);
+		return false;
+	}
+
+	*data = mb_maxhlm;
+
+	return true;
+}
+
 /*
  * Iterator finding enabled controls.
  * Dynamically traverses controls based on active control mode.
@@ -165,6 +188,17 @@ static int parse_bw(struct rdt_parse_data *data, struct rdt_resource_final *f,
 		return -EINVAL;
 	}
 
+	/* Parse mb_maxhlm line */
+	if (ctrl->name == RESCTRL_CTRL_NAME_MAXHLM) {
+		if (!mb_maxhlm_validate(data->buf, &bw_val, r, ctrl))
+			return -EINVAL;
+
+		cfg->new_ctrl = bw_val;
+		cfg->have_new_ctrl = true;
+		return 0;
+	}
+
+	/* Parse mb line */
 	if (!bw_validate(data->buf, &bw_val, r, ctrl))
 		return -EINVAL;
 
@@ -362,6 +396,7 @@ static const char * const resctrl_ctrl_name[] = {
 	[RESCTRL_CTRL_NAME_NODE]	= "NODE",
 	[RESCTRL_CTRL_NAME_REGION0_MIN]		= "REGION0_MIN",
 	[RESCTRL_CTRL_NAME_REGION0_MAX]		= "REGION0_MAX",
+	[RESCTRL_CTRL_NAME_MAXHLM]	= "MAXHLM",
 };
 
 const char *resctrl_ctrl_name_str(enum resctrl_ctrl_name name)
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index a16e35b587c4..01e69d0d9e96 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -4401,6 +4401,19 @@ static void rdtgroup_init_mba(struct rdt_resource *r, struct resctrl_ctrl *ctrl,
 	}
 }
 
+/* Initialize the MB MAXHLM control with default hardlim off (0). */
+static void rdtgroup_init_mb_hlim(struct resctrl_ctrl *ctrl)
+{
+	struct resctrl_staged_config *cfg;
+	struct rdt_ctrl_domain *d;
+
+	list_for_each_entry(d, &ctrl->domains, hdr.list) {
+		cfg = &d->staged_config[CDP_NONE];
+		cfg->new_ctrl = 0;
+		cfg->have_new_ctrl = true;
+	}
+}
+
 /* Initialize the RDT group's allocations. */
 static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
 {
@@ -4416,6 +4429,10 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
 		for_each_enabled_ctrl(ctrl, r) {
 			if (r->rid == RDT_RESOURCE_MBA ||
 			    r->rid == RDT_RESOURCE_SMBA) {
+				if (ctrl->name == RESCTRL_CTRL_NAME_MAXHLM) {
+					rdtgroup_init_mb_hlim(ctrl);
+					continue;
+				}
 				rdtgroup_init_mba(r, ctrl, rdtgrp->closid);
 				if (is_mba_sc(r, ctrl))
 					continue;
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 3c4675656b51..5711154145f8 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -402,6 +402,7 @@ struct resctrl_mon {
  *				line is "MB_NODE".
  * @RESCTRL_CTRL_NAME_REGION0_MIN:	"REGION0_MIN"
  * @RESCTRL_CTRL_NAME_REGION0_MAX:	"REGION0_MAX"
+ * @RESCTRL_CTRL_NAME_MAXHLM:	"MAXHLM"
  */
 enum resctrl_ctrl_name {
 	RESCTRL_CTRL_NAME_DEF,
@@ -410,7 +411,8 @@ enum resctrl_ctrl_name {
 	RESCTRL_CTRL_NAME_NODE,
 	RESCTRL_CTRL_NAME_REGION0_MIN,
 	RESCTRL_CTRL_NAME_REGION0_MAX,
-	RESCTRL_CTRL_NAME_LAST = RESCTRL_CTRL_NAME_REGION0_MAX
+	RESCTRL_CTRL_NAME_MAXHLM,
+	RESCTRL_CTRL_NAME_LAST = RESCTRL_CTRL_NAME_MAXHLM
 };
 
 /**
@@ -616,6 +618,10 @@ static inline u32 resctrl_get_default_ctrlval(struct resctrl_ctrl *ctrl)
 		 */
 		return BIT_MASK(ctrl->bitmap.cbm_len) - 1;
 	case RESCTRL_CTRL_SCALAR:
+		/* The hard-limit toggle defaults to off. */
+		if (ctrl->name == RESCTRL_CTRL_NAME_MAXHLM)
+			return 0;
+
 		return ctrl->scalar.reset_val;
 	}
 
-- 
2.53.0