3 files changed, 27 insertions, 1 deletions

diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
index caf53716ddb2..088dd34c8931 100644
--- a/drivers/vfio/group.c
+++ b/drivers/vfio/group.c
@@ -194,9 +194,18 @@ static int vfio_df_group_open(struct vfio_device_file *df)
 	df->iommufd = device->group->iommufd;
 
 	ret = vfio_df_open(df);
-	if (ret)
+	if (ret) {
 		df->iommufd = NULL;
+		goto out_put_kvm;
+	}
+
+	/*
+	 * Paired with smp_load_acquire() in vfio_device_fops::ioctl/
+	 * read/write/mmap and vfio_file_has_device_access()
+	 */
+	smp_store_release(&df->access_granted, true);
 
+out_put_kvm:
 	if (device->open_count == 0)
 		vfio_device_put_kvm(device);
 
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 2094f5a4ef04..4478a1e77a5e 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -19,6 +19,7 @@ struct vfio_container;
 struct vfio_device_file {
 	struct vfio_device *device;
 
+	u8 access_granted;
 	spinlock_t kvm_ref_lock; /* protect kvm field */
 	struct kvm *kvm;
 	struct iommufd_ctx *iommufd; /* protected by struct vfio_device_set::lock */
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 825b1eeaebe2..c37fc14599d0 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -1129,6 +1129,10 @@ static long vfio_device_fops_unl_ioctl(struct file *filep,
 	struct vfio_device *device = df->device;
 	int ret;
 
+	/* Paired with smp_store_release() following vfio_df_open() */
+	if (!smp_load_acquire(&df->access_granted))
+		return -EINVAL;
+
 	ret = vfio_device_pm_runtime_get(device);
 	if (ret)
 		return ret;
@@ -1156,6 +1160,10 @@ static ssize_t vfio_device_fops_read(struct file *filep, char __user *buf,
 	struct vfio_device_file *df = filep->private_data;
 	struct vfio_device *device = df->device;
 
+	/* Paired with smp_store_release() following vfio_df_open() */
+	if (!smp_load_acquire(&df->access_granted))
+		return -EINVAL;
+
 	if (unlikely(!device->ops->read))
 		return -EINVAL;
 
@@ -1169,6 +1177,10 @@ static ssize_t vfio_device_fops_write(struct file *filep,
 	struct vfio_device_file *df = filep->private_data;
 	struct vfio_device *device = df->device;
 
+	/* Paired with smp_store_release() following vfio_df_open() */
+	if (!smp_load_acquire(&df->access_granted))
+		return -EINVAL;
+
 	if (unlikely(!device->ops->write))
 		return -EINVAL;
 
@@ -1180,6 +1192,10 @@ static int vfio_device_fops_mmap(struct file *filep, struct vm_area_struct *vma)
 	struct vfio_device_file *df = filep->private_data;
 	struct vfio_device *device = df->device;
 
+	/* Paired with smp_store_release() following vfio_df_open() */
+	if (!smp_load_acquire(&df->access_granted))
+		return -EINVAL;
+
 	if (unlikely(!device->ops->mmap))
 		return -EINVAL;