x86/intel_rdt: Support creation/removal of pseudo-locked region

The user triggers the creation of a pseudo-locked region when writing a
valid schemata to the schemata file of a resource group in the
pseudo-locksetup mode.

A valid schemata is one that: (1) does not overlap with any other resource
group, (2) does not involve a cache that already contains a pseudo-locked
region within its hierarchy.

After a valid schemata is parsed the system is programmed to associate the
to be pseudo-lock bitmask with the closid associated with the resource
group. With the system set up the pseudo-locked region can be created.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: fenghua.yu@intel.com
Cc: tony.luck@intel.com
Cc: vikas.shivappa@linux.intel.com
Cc: gavin.hindman@intel.com
Cc: jithu.joseph@intel.com
Cc: dave.hansen@intel.com
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/8929c3a9e2ba600e79649abe584aa28b8d0ff639.1529706536.git.reinette.chatre@intel.com

arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c

@@ -143,9 +143,26 @@ int parse_cbm(void *_data, struct rdt_resource *r, struct rdt_domain *d)
 		return -EINVAL;
 	}
 
+	/*
+	 * Cannot set up more than one pseudo-locked region in a cache
+	 * hierarchy.
+	 */
+	if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP &&
+	    rdtgroup_pseudo_locked_in_hierarchy(d)) {
+		rdt_last_cmd_printf("pseudo-locked region in hierarchy\n");
+		return -EINVAL;
+	}
+
 	if (!cbm_validate(data->buf, &cbm_val, r))
 		return -EINVAL;
 
+	if ((rdtgrp->mode == RDT_MODE_EXCLUSIVE ||
+	     rdtgrp->mode == RDT_MODE_SHAREABLE) &&
+	    rdtgroup_cbm_overlaps_pseudo_locked(d, cbm_val)) {
+		rdt_last_cmd_printf("CBM overlaps with pseudo-locked region\n");
+		return -EINVAL;
+	}
+
 	/*
 	 * The CBM may not overlap with the CBM of another closid if
 	 * either is exclusive.
@@ -199,6 +216,21 @@ next:
 			data.rdtgrp = rdtgrp;
 			if (r->parse_ctrlval(&data, r, d))
 				return -EINVAL;
+			if (rdtgrp->mode ==  RDT_MODE_PSEUDO_LOCKSETUP) {
+				/*
+				 * In pseudo-locking setup mode and just
+				 * parsed a valid CBM that should be
+				 * pseudo-locked. Only one locked region per
+				 * resource group and domain so just do
+				 * the required initialization for single
+				 * region and return.
+				 */
+				rdtgrp->plr->r = r;
+				rdtgrp->plr->d = d;
+				rdtgrp->plr->cbm = d->new_ctrl;
+				d->plr = rdtgrp->plr;
+				return 0;
+			}
 			goto next;
 		}
 	}
@@ -322,6 +354,16 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
 			goto out;
 	}
 
+	if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
+		/*
+		 * If pseudo-locking fails we keep the resource group in
+		 * mode RDT_MODE_PSEUDO_LOCKSETUP with its class of service
+		 * active and updated for just the domain the pseudo-locked
+		 * region was requested for.
+		 */
+		ret = rdtgroup_pseudo_lock_create(rdtgrp);
+	}
+
 out:
 	rdtgroup_kn_unlock(of->kn);
 	return ret ?: nbytes;

arch/x86/kernel/cpu/intel_rdt_rdtgroup.c

@@ -1771,6 +1771,9 @@ void rdtgroup_kn_unlock(struct kernfs_node *kn)
 
 	if (atomic_dec_and_test(&rdtgrp->waitcount) &&
 	    (rdtgrp->flags & RDT_DELETED)) {
+		if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
+		    rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED)
+			rdtgroup_pseudo_lock_remove(rdtgrp);
 		kernfs_unbreak_active_protection(kn);
 		kernfs_put(rdtgrp->kn);
 		kfree(rdtgrp);
@@ -2002,6 +2005,10 @@ static void rmdir_all_sub(void)
 		if (rdtgrp == &rdtgroup_default)
 			continue;
 
+		if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
+		    rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED)
+			rdtgroup_pseudo_lock_remove(rdtgrp);
+
 		/*
 		 * Give any CPUs back to the default group. We cannot copy
 		 * cpu_online_mask because a CPU might have executed the
@@ -2313,6 +2320,8 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
 						d->new_ctrl |= *ctrl;
 				}
 			}
+			if (d->plr && d->plr->cbm > 0)
+				used_b |= d->plr->cbm;
 			unused_b = used_b ^ (BIT_MASK(r->cache.cbm_len) - 1);
 			unused_b &= BIT_MASK(r->cache.cbm_len) - 1;
 			d->new_ctrl |= unused_b;
@@ -2696,13 +2705,19 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)
 	 * If the rdtgroup is a mon group and parent directory
 	 * is a valid "mon_groups" directory, remove the mon group.
 	 */
-	if (rdtgrp->type == RDTCTRL_GROUP && parent_kn == rdtgroup_default.kn)
-		ret = rdtgroup_rmdir_ctrl(kn, rdtgrp, tmpmask);
-	else if (rdtgrp->type == RDTMON_GROUP &&
-		 is_mon_groups(parent_kn, kn->name))
+	if (rdtgrp->type == RDTCTRL_GROUP && parent_kn == rdtgroup_default.kn) {
+		if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
+		    rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
+			ret = rdtgroup_ctrl_remove(kn, rdtgrp);
+		} else {
+			ret = rdtgroup_rmdir_ctrl(kn, rdtgrp, tmpmask);
+		}
+	} else if (rdtgrp->type == RDTMON_GROUP &&
+		 is_mon_groups(parent_kn, kn->name)) {
 		ret = rdtgroup_rmdir_mon(kn, rdtgrp, tmpmask);
-	else
+	} else {
 		ret = -EPERM;
+	}
 
 out:
 	rdtgroup_kn_unlock(kn);