linux-kernel - [PATCH mpam mpam/snapshot+extras/v6.17-rc2 2/2] fs/resctrl: Migrate iommu

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Message-ID: <20251107063300.1580046-3-zengheng4@huawei.com>
Date: Fri, 7 Nov 2025 14:33:00 +0800
From: Zeng Heng <zengheng4@...wei.com>
To: <james.morse@....com>, <Dave.Martin@....com>, <ben.horgan@....com>
CC: <sunnanyong@...wei.com>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <zengheng4@...wei.com>,
	<jonathan.cameron@...wei.com>
Subject: [PATCH mpam mpam/snapshot+extras/v6.17-rc2 2/2] fs/resctrl: Migrate iommu_groups back when deleting the group

When deleting a control group or unmounting the resctrl file system, it
is necessary to move its all iommu_groups back to the default group. When
removing a monitor group, need to move its iommu_groups back to the parent
control group.

Otherwise, these iommu_groups remain bound to the old PARTID and PMG, and
they will appear to "disappear" from the resctrl fs.

By the way, remove the redundant formal parameter 'of' in
rdtgroup_move_iommu().

Signed-off-by: Zeng Heng <zengheng4@...wei.com>
---
 fs/resctrl/rdtgroup.c | 52 ++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 49 insertions(+), 3 deletions(-)

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 4f4468e11dca..e74e192e9876 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -773,8 +773,7 @@ static int rdtgroup_move_task(pid_t pid, struct rdtgroup *rdtgrp,
 	return ret;
 }
 
-static int rdtgroup_move_iommu(int iommu_group_id, struct rdtgroup *rdtgrp,
-			       struct kernfs_open_file *of)
+static int rdtgroup_move_iommu(int iommu_group_id, struct rdtgroup *rdtgrp)
 {
 	const struct cred *cred = current_cred();
 	struct iommu_group *iommu_group;
@@ -855,7 +854,7 @@ static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
 
 		is_iommu = string_is_iommu_group(pid_str, &iommu_group_id);
 		if (is_iommu) {
-			ret = rdtgroup_move_iommu(iommu_group_id, rdtgrp, of);
+			ret = rdtgroup_move_iommu(iommu_group_id, rdtgrp);
 			if (ret) {
 				rdt_last_cmd_printf("Error while processing iommu_group %d\n",
 						     iommu_group_id);
@@ -3161,6 +3160,44 @@ static void rdt_move_group_tasks(struct rdtgroup *from, struct rdtgroup *to,
 	read_unlock(&tasklist_lock);
 }
 
+static int rdt_move_group_iommus(struct rdtgroup *from, struct rdtgroup *to)
+{
+	int err, iommu_group_id;
+	struct kset *iommu_groups;
+	struct iommu_group *group;
+	struct kobject *group_kobj = NULL;
+
+	if (!IS_ENABLED(CONFIG_RESCTRL_IOMMU))
+		return 0;
+
+	if (from == to)
+		return 0;
+
+	iommu_groups = iommu_get_group_kset();
+
+	while ((group_kobj = kset_get_next_obj(iommu_groups, group_kobj))) {
+		/* iommu_group_get_from_kobj() wants to drop a reference */
+		kobject_get(group_kobj);
+
+		group = iommu_group_get_from_kobj(group_kobj);
+		if (!group)
+			continue;
+
+		if (!from || iommu_matches_rdtgroup(group, from)) {
+			err = kstrtoint(group_kobj->name, 0, &iommu_group_id);
+			if (err)
+				break;
+
+			err = rdtgroup_move_iommu(iommu_group_id, to);
+			if (err)
+				break;
+		}
+	}
+
+	kset_put(iommu_groups);
+	return err;
+}
+
 static void free_all_child_rdtgrp(struct rdtgroup *rdtgrp)
 {
 	struct rdtgroup *sentry, *stmp;
@@ -3188,6 +3225,9 @@ static void rmdir_all_sub(void)
 	/* Move all tasks to the default resource group */
 	rdt_move_group_tasks(NULL, &rdtgroup_default, NULL);
 
+	/* Move all iommu_groups to the default resource group */
+	rdt_move_group_iommus(NULL, &rdtgroup_default);
+
 	list_for_each_entry_safe(rdtgrp, tmp, &rdt_all_groups, rdtgroup_list) {
 		/* Free any child rmids */
 		free_all_child_rdtgrp(rdtgrp);
@@ -4050,6 +4090,9 @@ static int rdtgroup_rmdir_mon(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
 	/* Give any tasks back to the parent group */
 	rdt_move_group_tasks(rdtgrp, prdtgrp, tmpmask);
 
+	/* Give any iommu_groups back to the parent group */
+	rdt_move_group_iommus(rdtgrp, prdtgrp);
+
 	/*
 	 * Update per cpu closid/rmid of the moved CPUs first.
 	 * Note: the closid will not change, but the arch code still needs it.
@@ -4097,6 +4140,9 @@ static int rdtgroup_rmdir_ctrl(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
 	/* Give any tasks back to the default group */
 	rdt_move_group_tasks(rdtgrp, &rdtgroup_default, tmpmask);
 
+	/* Give any iommu_groups back to the default group */
+	rdt_move_group_iommus(rdtgrp, &rdtgroup_default);
+
 	/* Give any CPUs back to the default group */
 	cpumask_or(&rdtgroup_default.cpu_mask,
 		   &rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);
-- 
2.25.1