[PATCH v4 19/19] x86/resctrl: Introduce interface to modify assignment states of the groups

[Babu Moger <babu.moger@amd.com>]

Introduce the interface to enable events in ABMC mode.

Events can be enabled or disabled by writing to file
/sys/fs/resctrl/info/L3_MON/mbm_assign_control

Format is similar to the list format with addition of op-code for the
assignment operation.
 "<CTRL_MON group>/<MON group>/<op-code><assignment_flags>"

Format for specific type of groups:

 * Default CTRL_MON group:
         "//<domain_id><op-code><assignment_flags>"

 * Non-default CTRL_MON group:
         "<CTRL_MON group>//<domain_id><op-code><assignment_flags>"

 * Child MON group of default CTRL_MON group:
         "/<MON group>/<domain_id><op-code><assignment_flags>"

 * Child MON group of non-default CTRL_MON group:
         "<CTRL_MON group>/<MON group>/<domain_id><op-code><assignment_flags>"

Op-code can be one of the following:

 = Update the assignment to match the flags
 + enable a new state
 - disable a new state

Assignment flags can be one of the following:
 t  MBM total event is enabled
 l  MBM local event is enabled
 tl Both total and local MBM events are enabled
 _  None of the MBM events are enabled

Signed-off-by: Babu Moger <babu.moger@amd.com>
---
v4: Added domain specific assignments. Fixed the opcode parsing.

v3: New patch.
    Addresses the feedback to provide the global assignment interface.
    https://lore.kernel.org/lkml/c73f444b-83a1-4e9a-95d3-54c5165ee782@intel.com/
---
 Documentation/arch/x86/resctrl.rst     |  81 +++++++++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 242 ++++++++++++++++++++++++-
 2 files changed, 322 insertions(+), 1 deletion(-)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 255087de568d..89af91805b38 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -336,6 +336,87 @@ with the following files:
 	 /child_default_mon_grp/ - This is a child monitor group of the default control
 	 mon group.
 
+	Assignment state can be updated by writing to the interface.
+
+	Format is similar to the list format with addition of op-code for the
+	assignment operation.
+
+		"<CTRL_MON group>/<MON group>/<op-code><assignment_flags>"
+
+	Format for each type of groups:
+
+        * Default CTRL_MON group:
+                "//<domain_id><op-code><assignment_flags>"
+
+        * Non-default CTRL_MON group:
+                "<CTRL_MON group>//<domain_id><op-code><assignment_flags>"
+
+        * Child MON group of default CTRL_MON group:
+                "/<MON group>/<domain_id><op-code><assignment_flags>"
+
+        * Child MON group of non-default CTRL_MON group:
+                "<CTRL_MON group>/<MON group>/<domain_id><op-code><assignment_flags>"
+
+	Op-code can be one of the following:
+	::
+
+	 = Update the assignment to match the flags
+	 + Add a new state
+	 - delete a new state
+
+	Examples:
+	::
+
+	  Initial group status:
+	  # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
+	  non_default_ctrl_mon_grp//0=tl;1=tl;
+	  non_default_ctrl_mon_grp/child_non_default_mon_grp/0=tl;1=tl;
+	  //0=tl;1=tl;
+	  /child_default_mon_grp/0=tl;1=tl;
+
+	  To update the default group to enable only total event on domain 0:
+	  # echo "//0=t" > /sys/fs/resctrl/info/L3_MON/mbm_assign_control
+
+	  Assignment status after the update:
+	  # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
+	  non_default_ctrl_mon_grp//0=tl;1=tl;
+	  non_default_ctrl_mon_grp/child_non_default_mon_grp/0=tl;1=tl;
+	  //0=t;1=tl;2=tl;
+	  /child_default_mon_grp/0=tl;1=tl;
+
+	  To update the MON group child_default_mon_grp to remove total event on domain 1:
+	  # echo "/child_default_mon_grp/1-t" > /sys/fs/resctrl/info/L3_MON/mbm_assign_control
+
+	  Assignment status after the update:
+	  $ cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
+	  non_default_ctrl_mon_grp//0=tl;1=tl;
+	  non_default_ctrl_mon_grp/child_non_default_mon_grp/0=tl;1=tl;
+	  //0=t;1=l;
+	  /child_default_mon_grp/0=t;1=tl;
+
+	  To update the MON group non_default_ctrl_mon_grp/child_non_default_mon_grp to
+	  remove both local and total events on domain 1:
+	  # echo "non_default_ctrl_mon_grp/child_non_default_mon_grp/1=_" >
+			/sys/fs/resctrl/info/L3_MON/mbm_assign_control
+
+	  Assignment status after the update:
+	  # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
+	  non_default_ctrl_mon_grp//0=tl;1=tl;
+	  non_default_ctrl_mon_grp/child_non_default_mon_grp/0=tl;1=_;
+	  //0=t;1=l;
+	  /child_default_mon_grp/0=t;1=tl;
+
+	  To update the default group to add a total event domain 1.
+	  # echo "//1+t" > /sys/fs/resctrl/info/L3_MON/mbm_assign_control
+
+	  Assignment status after the update:
+
+	  # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
+	  non_default_ctrl_mon_grp//0=tl;1=tl;
+	  non_default_ctrl_mon_grp/child_non_default_mon_grp/0=tl;1=_;
+	  //0=t;1=tl;
+	  /child_default_mon_grp/0=t;1=tl;
+
 "max_threshold_occupancy":
 		Read/write file provides the largest value (in
 		bytes) at which a previously used LLC_occupancy
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index bd3a54405402..b74c18927bd2 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1068,6 +1068,245 @@ static int rdtgroup_mbm_assign_control_show(struct kernfs_open_file *of,
 	return 0;
 }
 
+static int str_to_mon_state(char *flag)
+{
+	int i, mon_state = 0;
+
+	for (i = 0; i < strlen(flag); i++) {
+		switch (*(flag + i)) {
+		case 't':
+			mon_state |= ASSIGN_TOTAL;
+			break;
+		case 'l':
+			mon_state |= ASSIGN_LOCAL;
+			break;
+		case '_':
+			mon_state = ASSIGN_NONE;
+			break;
+		default:
+			mon_state = ASSIGN_NONE;
+			break;
+		}
+	}
+
+	return mon_state;
+}
+
+static struct rdtgroup *resctrl_get_rdtgroup(enum rdt_group_type rtype, char *p_grp, char *c_grp)
+{
+	struct rdtgroup *rdtg, *crg;
+
+	if (rtype == RDTCTRL_GROUP && *p_grp == '\0') {
+		return &rdtgroup_default;
+	} else if (rtype == RDTCTRL_GROUP) {
+		list_for_each_entry(rdtg, &rdt_all_groups, rdtgroup_list)
+			if (!strcmp(p_grp, rdtg->kn->name))
+				return rdtg;
+	} else if (rtype == RDTMON_GROUP) {
+		list_for_each_entry(rdtg, &rdt_all_groups, rdtgroup_list) {
+			if (!strcmp(p_grp, rdtg->kn->name)) {
+				list_for_each_entry(crg, &rdtg->mon.crdtgrp_list,
+						    mon.crdtgrp_list) {
+					if (!strcmp(c_grp, crg->kn->name))
+						return crg;
+				}
+			}
+		}
+	}
+
+	return NULL;
+}
+
+static int resctrl_process_flags(enum rdt_group_type rtype, char *p_grp, char *c_grp, char *tok)
+{
+	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
+	int op, mon_state, assign_state, unassign_state;
+	char *dom_str, *id_str, *op_str;
+	struct rdtgroup *rdtgrp;
+	struct rdt_domain *d;
+	unsigned long dom_id;
+	int ret, found = 0;
+
+	rdtgrp = resctrl_get_rdtgroup(rtype, p_grp, c_grp);
+
+	if (!rdtgrp) {
+		rdt_last_cmd_puts("Not a valid resctrl group\n");
+		return -EINVAL;
+	}
+
+next:
+	if (!tok || tok[0] == '\0')
+		return 0;
+
+	/* Start processing the strings for each domain */
+	dom_str = strim(strsep(&tok, ";"));
+
+	op_str = strpbrk(dom_str, "=+-");
+
+	if (op_str) {
+		op = *op_str;
+	} else {
+		rdt_last_cmd_puts("Missing operation =, +, -, _ character\n");
+		return -EINVAL;
+	}
+
+	id_str = strsep(&dom_str, "=+-");
+
+	if (!id_str || kstrtoul(id_str, 10, &dom_id)) {
+		rdt_last_cmd_puts("Missing domain id\n");
+		return -EINVAL;
+	}
+
+	/* Verify if the dom_id is valid */
+	list_for_each_entry(d, &r->domains, list) {
+		if (d->id == dom_id) {
+			found = 1;
+			break;
+		}
+	}
+	if (!found) {
+		rdt_last_cmd_printf("Invalid domain id %ld\n", dom_id);
+		return -EINVAL;
+	}
+
+	mon_state = str_to_mon_state(dom_str);
+
+	assign_state = 0;
+	unassign_state = 0;
+
+	switch (op) {
+	case '+':
+		assign_state = mon_state;
+		break;
+	case '-':
+		unassign_state = mon_state;
+		break;
+	case '=':
+		assign_state = mon_state;
+		unassign_state = (ASSIGN_TOTAL | ASSIGN_LOCAL) & ~assign_state;
+		break;
+	default:
+		break;
+	}
+
+	if (assign_state & ASSIGN_TOTAL)
+		ret = resctrl_arch_assign(d, QOS_L3_MBM_TOTAL_EVENT_ID,
+					  rdtgrp->mon.rmid,
+					  rdtgrp->mon.ctr_id[0],
+					  rdtgrp->closid, 1);
+	if (ret)
+		goto out_fail;
+
+	if (assign_state & ASSIGN_LOCAL)
+		ret = resctrl_arch_assign(d, QOS_L3_MBM_LOCAL_EVENT_ID,
+					  rdtgrp->mon.rmid,
+					  rdtgrp->mon.ctr_id[1],
+					  rdtgrp->closid, 1);
+
+	if (ret)
+		goto out_fail;
+
+	if (unassign_state & ASSIGN_TOTAL)
+		ret = resctrl_arch_assign(d, QOS_L3_MBM_TOTAL_EVENT_ID,
+					  rdtgrp->mon.rmid,
+					  rdtgrp->mon.ctr_id[0],
+					  rdtgrp->closid, 0);
+
+	if (ret)
+		goto out_fail;
+
+	if (unassign_state & ASSIGN_LOCAL)
+		ret = resctrl_arch_assign(d, QOS_L3_MBM_LOCAL_EVENT_ID,
+					  rdtgrp->mon.rmid,
+					  rdtgrp->mon.ctr_id[1],
+					  rdtgrp->closid, 0);
+	if (ret)
+		goto out_fail;
+
+	goto next;
+
+out_fail:
+
+	return -EINVAL;
+}
+
+static ssize_t rdtgroup_mbm_assign_control_write(struct kernfs_open_file *of,
+						 char *buf, size_t nbytes,
+						 loff_t off)
+{
+	struct rdt_resource *r = of->kn->parent->priv;
+	char *token, *cmon_grp, *mon_grp;
+	struct rdt_hw_resource *hw_res;
+	int ret;
+
+	hw_res = resctrl_to_arch_res(r);
+	if (!hw_res->abmc_enabled)
+		return -EINVAL;
+
+	/* Valid input requires a trailing newline */
+	if (nbytes == 0 || buf[nbytes - 1] != '\n')
+		return -EINVAL;
+
+	buf[nbytes - 1] = '\0';
+	rdt_last_cmd_clear();
+
+	cpus_read_lock();
+	mutex_lock(&rdtgroup_mutex);
+
+	while ((token = strsep(&buf, "\n")) != NULL) {
+		if (strstr(token, "//")) {
+			/*
+			 * The control mon group processing:
+			 * default CTRL_MON group: "//<flags>"
+			 * non-default CTRL_MON group: "<CTRL_MON group>//flags"
+			 * The CTRL_MON group will be empty string if it is a
+			 * default group.
+			 */
+			cmon_grp = strsep(&token, "//");
+
+			/*
+			 * strsep returns empty string for contiguous delimiters.
+			 * Make sure check for two consicutive delimiters and
+			 * advance the token.
+			 */
+			mon_grp = strsep(&token, "//");
+			if (*mon_grp != '\0') {
+				rdt_last_cmd_printf("Invalid CTRL_MON group format %s\n", token);
+				ret = -EINVAL;
+				break;
+			}
+
+			ret = resctrl_process_flags(RDTCTRL_GROUP, cmon_grp, mon_grp, token);
+			if (ret)
+				break;
+		} else if (strstr(token, "/")) {
+			/*
+			 * Mon group processing:
+			 * MON_GROUP inside default CTRL_MON group: "/<MON group>/<flags>"
+			 * MON_GROUP within CTRL_MON group: "<CTRL_MON group>/<MON group>/<flags>"
+			 */
+			cmon_grp = strsep(&token, "/");
+
+			/* Extract the MON_GROUP. It cannot be empty string */
+			mon_grp = strsep(&token, "/");
+			if (*mon_grp == '\0') {
+				rdt_last_cmd_printf("Invalid MON_GROUP format %s\n", token);
+				ret = -EINVAL;
+				break;
+			}
+
+			ret = resctrl_process_flags(RDTMON_GROUP, cmon_grp, mon_grp, token);
+			if (ret)
+				break;
+		}
+	}
+
+	mutex_unlock(&rdtgroup_mutex);
+	cpus_read_unlock();
+
+	return ret ?: nbytes;
+}
+
 #ifdef CONFIG_PROC_CPU_RESCTRL
 
 /*
@@ -2268,9 +2507,10 @@ static struct rftype res_common_files[] = {
 	},
 	{
 		.name		= "mbm_assign_control",
-		.mode		= 0444,
+		.mode		= 0644,
 		.kf_ops		= &rdtgroup_kf_single_ops,
 		.seq_show	= rdtgroup_mbm_assign_control_show,
+		.write		= rdtgroup_mbm_assign_control_write,
 	},
 	{
 		.name		= "cpus_list",
-- 
2.34.1