[PATCH 5/6] iommu/amd: Lock dev_data in attach/detach code paths

[Joerg Roedel <joro@8bytes.org>]

From: Joerg Roedel <jroedel@suse.de>

Make sure that attaching a detaching a device can't race against each
other and protect the iommu_dev_data with a spin_lock in these code
paths.

Fixes: 92d420ec028d ("iommu/amd: Relax locking in dma_ops path")
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/amd_iommu.c       | 9 +++++++++
 drivers/iommu/amd_iommu_types.h | 3 +++
 2 files changed, 12 insertions(+)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 459247c32dc0..bac4e20a5919 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -201,6 +201,7 @@ static struct iommu_dev_data *alloc_dev_data(u16 devid)
 	if (!dev_data)
 		return NULL;
 
+	spin_lock_init(&dev_data->lock);
 	dev_data->devid = devid;
 	ratelimit_default_init(&dev_data->rs);
 
@@ -2157,6 +2158,8 @@ static int attach_device(struct device *dev,
 
 	dev_data = get_dev_data(dev);
 
+	spin_lock(&dev_data->lock);
+
 	ret = -EBUSY;
 	if (dev_data->domain != NULL)
 		goto out;
@@ -2199,6 +2202,8 @@ static int attach_device(struct device *dev,
 	domain_flush_complete(domain);
 
 out:
+	spin_unlock(&dev_data->lock);
+
 	spin_unlock_irqrestore(&domain->lock, flags);
 
 	return ret;
@@ -2218,6 +2223,8 @@ static void detach_device(struct device *dev)
 
 	spin_lock_irqsave(&domain->lock, flags);
 
+	spin_lock(&dev_data->lock);
+
 	/*
 	 * First check if the device is still attached. It might already
 	 * be detached from its domain because the generic
@@ -2240,6 +2247,8 @@ static void detach_device(struct device *dev)
 	dev_data->ats.enabled = false;
 
 out:
+	spin_unlock(&dev_data->lock);
+
 	spin_unlock_irqrestore(&domain->lock, flags);
 }
 
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index 0186501ab971..c9c1612d52e0 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -633,6 +633,9 @@ struct devid_map {
  * This struct contains device specific data for the IOMMU
  */
 struct iommu_dev_data {
+	/*Protect against attach/detach races */
+	spinlock_t lock;
+
 	struct list_head list;		  /* For domain->dev_list */
 	struct llist_node dev_data_list;  /* For global dev_data_list */
 	struct protection_domain *domain; /* Domain the device is bound to */
-- 
2.17.1

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