iommu/amd: Remove amd_iommu_devtable_lock

The lock is not necessary because the device table does not
contain shared state that needs protection. Locking is only
needed on an individual entry basis, and that needs to
happen on the iommu_dev_data level.

Fixes: 92d420e ("iommu/amd: Relax locking in dma_ops path")
Reviewed-by: Filippo Sironi <[email protected]>
Reviewed-by: Jerry Snitselaar <[email protected]>
Signed-off-by: Joerg Roedel <[email protected]>

Author: joergroedel

drivers/iommu/amd_iommu.c

@@ -70,7 +70,6 @@
  */
 #define AMD_IOMMU_PGSIZES	((~0xFFFUL) & ~(2ULL << 38))
 
-static DEFINE_SPINLOCK(amd_iommu_devtable_lock);
 static DEFINE_SPINLOCK(pd_bitmap_lock);
 
 /* List of all available dev_data structures */
@@ -2080,10 +2079,11 @@ static void do_detach(struct iommu_dev_data *dev_data)
 static int __attach_device(struct iommu_dev_data *dev_data,
 			   struct protection_domain *domain)
 {
+	unsigned long flags;
 	int ret;
 
 	/* lock domain */
-	spin_lock(&domain->lock);
+	spin_lock_irqsave(&domain->lock, flags);
 
 	ret = -EBUSY;
 	if (dev_data->domain != NULL)
@@ -2097,7 +2097,7 @@ static int __attach_device(struct iommu_dev_data *dev_data,
 out_unlock:
 
 	/* ready */
-	spin_unlock(&domain->lock);
+	spin_unlock_irqrestore(&domain->lock, flags);
 
 	return ret;
 }
@@ -2181,7 +2181,6 @@ static int attach_device(struct device *dev,
 {
 	struct pci_dev *pdev;
 	struct iommu_dev_data *dev_data;
-	unsigned long flags;
 	int ret;
 
 	dev_data = get_dev_data(dev);
@@ -2209,9 +2208,7 @@ static int attach_device(struct device *dev,
 	}
 
 skip_ats_check:
-	spin_lock_irqsave(&amd_iommu_devtable_lock, flags);
 	ret = __attach_device(dev_data, domain);
-	spin_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
 
 	/*
 	 * We might boot into a crash-kernel here. The crashed kernel
@@ -2231,14 +2228,15 @@ static int attach_device(struct device *dev,
 static void __detach_device(struct iommu_dev_data *dev_data)
 {
 	struct protection_domain *domain;
+	unsigned long flags;
 
 	domain = dev_data->domain;
 
-	spin_lock(&domain->lock);
+	spin_lock_irqsave(&domain->lock, flags);
 
 	do_detach(dev_data);
 
-	spin_unlock(&domain->lock);
+	spin_unlock_irqrestore(&domain->lock, flags);
 }
 
 /*
@@ -2248,7 +2246,6 @@ static void detach_device(struct device *dev)
 {
 	struct protection_domain *domain;
 	struct iommu_dev_data *dev_data;
-	unsigned long flags;
 
 	dev_data = get_dev_data(dev);
 	domain   = dev_data->domain;
@@ -2262,10 +2259,7 @@ static void detach_device(struct device *dev)
 	if (WARN_ON(!dev_data->domain))
 		return;
 
-	/* lock device table */
-	spin_lock_irqsave(&amd_iommu_devtable_lock, flags);
 	__detach_device(dev_data);
-	spin_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
 
 	if (!dev_is_pci(dev))
 		return;
@@ -2910,18 +2904,13 @@ int __init amd_iommu_init_dma_ops(void)
 static void cleanup_domain(struct protection_domain *domain)
 {
 	struct iommu_dev_data *entry;
-	unsigned long flags;
-
-	spin_lock_irqsave(&amd_iommu_devtable_lock, flags);
 
 	while (!list_empty(&domain->dev_list)) {
 		entry = list_first_entry(&domain->dev_list,
 					 struct iommu_dev_data, list);
 		BUG_ON(!entry->domain);
 		__detach_device(entry);
 	}
-
-	spin_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
 }
 
 static void protection_domain_free(struct protection_domain *domain)