iommu/amd: Split domain id out of amd_iommu_devtable_lock

domain_id_alloc() and domain_id_free() is used for id management. Those
two function share a bitmap (amd_iommu_pd_alloc_bitmap) and set/clear
bits based on id allocation. There is no need to share this with
amd_iommu_devtable_lock, it can use its own lock for this operation.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/amd_iommu.c

@@ -81,6 +81,7 @@
 #define AMD_IOMMU_PGSIZES	((~0xFFFUL) & ~(2ULL << 38))
 
 static DEFINE_RWLOCK(amd_iommu_devtable_lock);
+static DEFINE_SPINLOCK(pd_bitmap_lock);
 
 /* List of all available dev_data structures */
 static LLIST_HEAD(dev_data_list);
@@ -1600,29 +1601,26 @@ static void del_domain_from_list(struct protection_domain *domain)
 
 static u16 domain_id_alloc(void)
 {
-	unsigned long flags;
 	int id;
 
-	write_lock_irqsave(&amd_iommu_devtable_lock, flags);
+	spin_lock(&pd_bitmap_lock);
 	id = find_first_zero_bit(amd_iommu_pd_alloc_bitmap, MAX_DOMAIN_ID);
 	BUG_ON(id == 0);
 	if (id > 0 && id < MAX_DOMAIN_ID)
 		__set_bit(id, amd_iommu_pd_alloc_bitmap);
 	else
 		id = 0;
-	write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
+	spin_unlock(&pd_bitmap_lock);
 
 	return id;
 }
 
 static void domain_id_free(int id)
 {
-	unsigned long flags;
-
-	write_lock_irqsave(&amd_iommu_devtable_lock, flags);
+	spin_lock(&pd_bitmap_lock);
 	if (id > 0 && id < MAX_DOMAIN_ID)
 		__clear_bit(id, amd_iommu_pd_alloc_bitmap);
-	write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
+	spin_unlock(&pd_bitmap_lock);
 }
 
 #define DEFINE_FREE_PT_FN(LVL, FN)				\