1 files changed, 13 insertions, 5 deletions

diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index d4daa05efe60..499b4366a98d 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -45,7 +45,7 @@ struct pri_queue {
 struct pasid_state {
         struct list_head list;                  /* For global state-list */
         atomic_t count;                         /* Reference count */
-        atomic_t mmu_notifier_count;            /* Counting nested mmu_notifier
+        unsigned mmu_notifier_count;            /* Counting nested mmu_notifier
                                                    calls */
         struct task_struct *task;               /* Task bound to this PASID */
         struct mm_struct *mm;                   /* mm_struct for the faults */
@@ -53,7 +53,8 @@ struct pasid_state {
         struct pri_queue pri[PRI_QUEUE_SIZE];   /* PRI tag states */
         struct device_state *device_state;      /* Link to our device_state */
         int pasid;                              /* PASID index */
-        spinlock_t lock;                        /* Protect pri_queues */
+        spinlock_t lock;                        /* Protect pri_queues and
+                                                   mmu_notifer_count */
         wait_queue_head_t wq;                   /* To wait for count == 0 */
 };
 
@@ -431,15 +432,19 @@ static void mn_invalidate_range_start(struct mmu_notifier *mn,
 {
         struct pasid_state *pasid_state;
         struct device_state *dev_state;
+        unsigned long flags;
 
         pasid_state = mn_to_state(mn);
         dev_state   = pasid_state->device_state;
 
-        if (atomic_add_return(1, &pasid_state->mmu_notifier_count) == 1) {
+        spin_lock_irqsave(&pasid_state->lock, flags);
+        if (pasid_state->mmu_notifier_count == 0) {
                 amd_iommu_domain_set_gcr3(dev_state->domain,
                                           pasid_state->pasid,
                                           __pa(empty_page_table));
         }
+        pasid_state->mmu_notifier_count += 1;
+        spin_unlock_irqrestore(&pasid_state->lock, flags);
 }
 
 static void mn_invalidate_range_end(struct mmu_notifier *mn,
@@ -448,15 +453,19 @@ static void mn_invalidate_range_end(struct mmu_notifier *mn,
 {
         struct pasid_state *pasid_state;
         struct device_state *dev_state;
+        unsigned long flags;
 
         pasid_state = mn_to_state(mn);
         dev_state   = pasid_state->device_state;
 
-        if (atomic_dec_and_test(&pasid_state->mmu_notifier_count)) {
+        spin_lock_irqsave(&pasid_state->lock, flags);
+        pasid_state->mmu_notifier_count -= 1;
+        if (pasid_state->mmu_notifier_count == 0) {
                 amd_iommu_domain_set_gcr3(dev_state->domain,
                                           pasid_state->pasid,
                                           __pa(pasid_state->mm->pgd));
         }
+        spin_unlock_irqrestore(&pasid_state->lock, flags);
 }
 
 static void mn_release(struct mmu_notifier *mn, struct mm_struct *mm)
@@ -650,7 +659,6 @@ int amd_iommu_bind_pasid(struct pci_dev *pdev, int pasid,
                 goto out;
 
         atomic_set(&pasid_state->count, 1);
-        atomic_set(&pasid_state->mmu_notifier_count, 0);
         init_waitqueue_head(&pasid_state->wq);
         spin_lock_init(&pasid_state->lock);