iommu/amd: Lock dev_data in attach/detach code paths

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: 92d420ec02 ("iommu/amd: Relax locking in dma_ops path")
Reviewed-by: Filippo Sironi <sironi@amazon.de>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

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 @@ skip_ats_check:
 	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);
 }
 

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 */