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

Babu Moger
2024-05-24T12:26:28Z

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