x86/intel_rdt/cqm: Add cpus file support

The cpus file is extended to support resource monitoring. This is used
to over-ride the RMID of the default group when running on specific
CPUs. It works similar to the resource control. The "cpus" and
"cpus_list" file is present in default group, ctrl_mon groups and
monitor groups.

Each "cpus" file or cpu_list file reads a cpumask or list showing which
CPUs belong to the resource group. By default all online cpus belong to
the default root group. A CPU can be present in one "ctrl_mon" and one
"monitor" group simultaneously. They can be added to a resource group by
writing the CPU to the file. When a CPU is added to a ctrl_mon group it
is automatically removed from the previous ctrl_mon group. A CPU can be
added to a monitor group only if it is present in the parent ctrl_mon
group and when a CPU is added to a monitor group, it is automatically
removed from the previous monitor group. When CPUs go offline, they are
automatically removed from the ctrl_mon and monitor groups.

Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Cc: vikas.shivappa@intel.com
Cc: ak@linux.intel.com
Cc: davidcc@google.com
Cc: reinette.chatre@intel.com
Link: http://lkml.kernel.org/r/1501017287-28083-18-git-send-email-vikas.shivappa@linux.intel.com

1 files changed, 93 insertions, 17 deletions

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index d11f4629a702..89457bba457a 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -181,15 +181,17 @@ static int rdtgroup_cpus_show(struct kernfs_open_file *of,
 /*
  * This is safe against intel_rdt_sched_in() called from __switch_to()
  * because __switch_to() is executed with interrupts disabled. A local call
- * from update_closid() is proteced against __switch_to() because
+ * from update_closid_rmid() is proteced against __switch_to() because
  * preemption is disabled.
  */
-static void update_cpu_closid(void *info)
+static void update_cpu_closid_rmid(void *info)
 {
         struct rdtgroup *r = info;
 
-        if (r)
+        if (r) {
                 this_cpu_write(rdt_cpu_default.closid, r->closid);
+                this_cpu_write(rdt_cpu_default.rmid, r->mon.rmid);
+        }
 
         /*
          * We cannot unconditionally write the MSR because the current
@@ -205,20 +207,72 @@ static void update_cpu_closid(void *info)
  * Per task closids/rmids must have been set up before calling this function.
  */
 static void
-update_closid(const struct cpumask *cpu_mask, struct rdtgroup *r)
+update_closid_rmid(const struct cpumask *cpu_mask, struct rdtgroup *r)
 {
         int cpu = get_cpu();
 
         if (cpumask_test_cpu(cpu, cpu_mask))
-                update_cpu_closid(r);
-        smp_call_function_many(cpu_mask, update_cpu_closid, r, 1);
+                update_cpu_closid_rmid(r);
+        smp_call_function_many(cpu_mask, update_cpu_closid_rmid, r, 1);
         put_cpu();
 }
 
+static int cpus_mon_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
+                          cpumask_var_t tmpmask)
+{
+        struct rdtgroup *prgrp = rdtgrp->mon.parent, *crgrp;
+        struct list_head *head;
+
+        /* Check whether cpus belong to parent ctrl group */
+        cpumask_andnot(tmpmask, newmask, &prgrp->cpu_mask);
+        if (cpumask_weight(tmpmask))
+                return -EINVAL;
+
+        /* Check whether cpus are dropped from this group */
+        cpumask_andnot(tmpmask, &rdtgrp->cpu_mask, newmask);
+        if (cpumask_weight(tmpmask)) {
+                /* Give any dropped cpus to parent rdtgroup */
+                cpumask_or(&prgrp->cpu_mask, &prgrp->cpu_mask, tmpmask);
+                update_closid_rmid(tmpmask, prgrp);
+        }
+
+        /*
+         * If we added cpus, remove them from previous group that owned them
+         * and update per-cpu rmid
+         */
+        cpumask_andnot(tmpmask, newmask, &rdtgrp->cpu_mask);
+        if (cpumask_weight(tmpmask)) {
+                head = &prgrp->mon.crdtgrp_list;
+                list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
+                        if (crgrp == rdtgrp)
+                                continue;
+                        cpumask_andnot(&crgrp->cpu_mask, &crgrp->cpu_mask,
+                                       tmpmask);
+                }
+                update_closid_rmid(tmpmask, rdtgrp);
+        }
+
+        /* Done pushing/pulling - update this group with new mask */
+        cpumask_copy(&rdtgrp->cpu_mask, newmask);
+
+        return 0;
+}
+
+static void cpumask_rdtgrp_clear(struct rdtgroup *r, struct cpumask *m)
+{
+        struct rdtgroup *crgrp;
+
+        cpumask_andnot(&r->cpu_mask, &r->cpu_mask, m);
+        /* update the child mon group masks as well*/
+        list_for_each_entry(crgrp, &r->mon.crdtgrp_list, mon.crdtgrp_list)
+                cpumask_and(&crgrp->cpu_mask, &r->cpu_mask, &crgrp->cpu_mask);
+}
+
 static int cpus_ctrl_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
-                           cpumask_var_t tmpmask)
+                           cpumask_var_t tmpmask, cpumask_var_t tmpmask1)
 {
-        struct rdtgroup *r;
+        struct rdtgroup *r, *crgrp;
+        struct list_head *head;
 
         /* Check whether cpus are dropped from this group */
         cpumask_andnot(tmpmask, &rdtgrp->cpu_mask, newmask);
@@ -230,33 +284,47 @@ static int cpus_ctrl_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
                 /* Give any dropped cpus to rdtgroup_default */
                 cpumask_or(&rdtgroup_default.cpu_mask,
                            &rdtgroup_default.cpu_mask, tmpmask);
-                update_closid(tmpmask, &rdtgroup_default);
+                update_closid_rmid(tmpmask, &rdtgroup_default);
         }
 
         /*
-         * If we added cpus, remove them from previous group that owned them
-         * and update per-cpu closid
+         * If we added cpus, remove them from previous group and
+         * the prev group's child groups that owned them
+         * and update per-cpu closid/rmid.
          */
         cpumask_andnot(tmpmask, newmask, &rdtgrp->cpu_mask);
         if (cpumask_weight(tmpmask)) {
                 list_for_each_entry(r, &rdt_all_groups, rdtgroup_list) {
                         if (r == rdtgrp)
                                 continue;
-                        cpumask_andnot(&r->cpu_mask, &r->cpu_mask, tmpmask);
+                        cpumask_and(tmpmask1, &r->cpu_mask, tmpmask);
+                        if (cpumask_weight(tmpmask1))
+                                cpumask_rdtgrp_clear(r, tmpmask1);
                 }
-                update_closid(tmpmask, rdtgrp);
+                update_closid_rmid(tmpmask, rdtgrp);
         }
 
         /* Done pushing/pulling - update this group with new mask */
         cpumask_copy(&rdtgrp->cpu_mask, newmask);
 
+        /*
+         * Clear child mon group masks since there is a new parent mask
+         * now and update the rmid for the cpus the child lost.
+         */
+        head = &rdtgrp->mon.crdtgrp_list;
+        list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
+                cpumask_and(tmpmask, &rdtgrp->cpu_mask, &crgrp->cpu_mask);
+                update_closid_rmid(tmpmask, rdtgrp);
+                cpumask_clear(&crgrp->cpu_mask);
+        }
+
         return 0;
 }
 
 static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
                                    char *buf, size_t nbytes, loff_t off)
 {
-        cpumask_var_t tmpmask, newmask;
+        cpumask_var_t tmpmask, newmask, tmpmask1;
         struct rdtgroup *rdtgrp;
         int ret;
 
@@ -269,6 +337,11 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
                 free_cpumask_var(tmpmask);
                 return -ENOMEM;
         }
+        if (!zalloc_cpumask_var(&tmpmask1, GFP_KERNEL)) {
+                free_cpumask_var(tmpmask);
+                free_cpumask_var(newmask);
+                return -ENOMEM;
+        }
 
         rdtgrp = rdtgroup_kn_lock_live(of->kn);
         if (!rdtgrp) {
@@ -292,7 +365,9 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
         }
 
         if (rdtgrp->type == RDTCTRL_GROUP)
-                ret = cpus_ctrl_write(rdtgrp, newmask, tmpmask);
+                ret = cpus_ctrl_write(rdtgrp, newmask, tmpmask, tmpmask1);
+        else if (rdtgrp->type == RDTMON_GROUP)
+                ret = cpus_mon_write(rdtgrp, newmask, tmpmask);
         else
                 ret = -EINVAL;
 
@@ -300,6 +375,7 @@ unlock:
         rdtgroup_kn_unlock(of->kn);
         free_cpumask_var(tmpmask);
         free_cpumask_var(newmask);
+        free_cpumask_var(tmpmask1);
 
         return ret ?: nbytes;
 }
@@ -1113,7 +1189,7 @@ static void rmdir_all_sub(void)
         }
         /* Notify online CPUs to update per cpu storage and PQR_ASSOC MSR */
         get_online_cpus();
-        update_closid(cpu_online_mask, &rdtgroup_default);
+        update_closid_rmid(cpu_online_mask, &rdtgroup_default);
         put_online_cpus();
 
         kernfs_remove(kn_info);
@@ -1374,7 +1450,7 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)
          * task running on them.
          */
         cpumask_or(tmpmask, tmpmask, &rdtgrp->cpu_mask);
-        update_closid(tmpmask, NULL);
+        update_closid_rmid(tmpmask, NULL);
 
         rdtgrp->flags = RDT_DELETED;
         closid_free(rdtgrp->closid);