linux-kernel - [PATCH 4/4] iommu: Cleanup iommu_change_dev_def

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Message-Id: <20230213074941.919324-5-baolu.lu@linux.intel.com>
Date:   Mon, 13 Feb 2023 15:49:41 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     iommu@...ts.linux.dev
Cc:     Joerg Roedel <joro@...tes.org>, Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        linux-kernel@...r.kernel.org, Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH 4/4] iommu: Cleanup iommu_change_dev_def_domain()

As the singleton group limitation has been removed, cleanup the code
in iommu_change_dev_def_domain() accordingly.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/iommu.c | 41 ++++++++++-------------------------------
 1 file changed, 10 insertions(+), 31 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 1e69def20a67..67b978403a05 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2783,7 +2783,7 @@ int iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat)
 EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);
 
 /*
- * Changes the default domain of an iommu group that has *only* one device
+ * Changes the default domain of an iommu group
  *
  * @group: The group for which the default domain should be changed
  * @type: The type of the new default domain that gets associated with the group
@@ -2797,33 +2797,14 @@ EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);
  */
 static int iommu_change_dev_def_domain(struct iommu_group *group, int type)
 {
+	struct __group_domain_type gtype = {NULL, 0};
 	struct iommu_domain *prev_dom;
 	struct group_device *grp_dev;
-	int ret, dev_def_dom;
 	struct device *dev;
+	int ret;
 
 	mutex_lock(&group->mutex);
 
-	/*
-	 * iommu group wasn't locked while acquiring device lock in
-	 * iommu_group_store_type(). So, make sure that the device count hasn't
-	 * changed while acquiring device lock.
-	 *
-	 * Changing default domain of an iommu group with two or more devices
-	 * isn't supported because there could be a potential deadlock. Consider
-	 * the following scenario. T1 is trying to acquire device locks of all
-	 * the devices in the group and before it could acquire all of them,
-	 * there could be another thread T2 (from different sub-system and use
-	 * case) that has already acquired some of the device locks and might be
-	 * waiting for T1 to release other device locks.
-	 */
-	if (iommu_group_device_count(group) != 1) {
-		pr_err_ratelimited("Cannot change default domain: Group has more than one device\n");
-		ret = -EINVAL;
-		goto out;
-	}
-
-	/* Since group has only one device */
 	grp_dev = list_first_entry(&group->devices, struct group_device, list);
 	dev = grp_dev->dev;
 
@@ -2833,15 +2814,16 @@ static int iommu_change_dev_def_domain(struct iommu_group *group, int type)
 		goto out;
 	}
 
-	dev_def_dom = iommu_get_def_domain_type(dev);
+	__iommu_group_for_each_dev(group, &gtype,
+				   probe_get_default_domain_type);
 	if (!type) {
 		/*
 		 * If the user hasn't requested any specific type of domain and
 		 * if the device supports both the domains, then default to the
 		 * domain the device was booted with
 		 */
-		type = dev_def_dom ? : iommu_def_domain_type;
-	} else if (dev_def_dom && type != dev_def_dom) {
+		type = gtype.type ? : iommu_def_domain_type;
+	} else if (gtype.type && type != gtype.type) {
 		pr_err_ratelimited("Device cannot be in %s domain\n",
 				   iommu_domain_type_str(type));
 		ret = -EINVAL;
@@ -2870,16 +2852,14 @@ static int iommu_change_dev_def_domain(struct iommu_group *group, int type)
 	if (ret)
 		goto out;
 
-	ret = iommu_create_device_direct_mappings(group, dev);
+	ret = iommu_group_create_direct_mappings(group);
 	if (ret)
 		goto free_new_domain;
 
-	ret = __iommu_attach_device(group->default_domain, dev);
+	ret = __iommu_attach_group(group->default_domain, group);
 	if (ret)
 		goto free_new_domain;
 
-	group->domain = group->default_domain;
-
 	/*
 	 * Release the mutex here because ops->probe_finalize() call-back of
 	 * some vendor IOMMU drivers calls arm_iommu_attach_device() which
@@ -2889,7 +2869,7 @@ static int iommu_change_dev_def_domain(struct iommu_group *group, int type)
 	mutex_unlock(&group->mutex);
 
 	/* Make sure dma_ops is appropriatley set */
-	iommu_group_do_probe_finalize(dev, group->default_domain);
+	__iommu_group_dma_finalize(group);
 	iommu_domain_free(prev_dom);
 	return 0;
 
@@ -2897,7 +2877,6 @@ static int iommu_change_dev_def_domain(struct iommu_group *group, int type)
 	iommu_domain_free(group->default_domain);
 	group->default_domain = prev_dom;
 	group->domain = prev_dom;
-
 out:
 	mutex_unlock(&group->mutex);
 
-- 
2.34.1