[PATCH V2 3/5] vfio/type1: revert "block on invalid vaddr"

[Steve Sistare <steven.sistare@oracle.com>]

Revert this dead code:
  commit 898b9eaeb3fe ("vfio/type1: block on invalid vaddr")

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 drivers/vfio/vfio_iommu_type1.c | 94 +++--------------------------------------
 1 file changed, 5 insertions(+), 89 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 35a1a52..d4f961d 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -72,7 +72,6 @@ struct vfio_iommu {
 	unsigned int		vaddr_invalid_count;
 	uint64_t		pgsize_bitmap;
 	uint64_t		num_non_pinned_groups;
-	wait_queue_head_t	vaddr_wait;
 	bool			v2;
 	bool			nesting;
 	bool			dirty_page_tracking;
@@ -153,8 +152,6 @@ struct vfio_regions {
 #define DIRTY_BITMAP_PAGES_MAX	 ((u64)INT_MAX)
 #define DIRTY_BITMAP_SIZE_MAX	 DIRTY_BITMAP_BYTES(DIRTY_BITMAP_PAGES_MAX)
 
-#define WAITED 1
-
 static int put_pfn(unsigned long pfn, int prot);
 
 static struct vfio_iommu_group*
@@ -596,61 +593,6 @@ static int vaddr_get_pfns(struct mm_struct *mm, unsigned long vaddr,
 	return ret;
 }
 
-static int vfio_wait(struct vfio_iommu *iommu)
-{
-	DEFINE_WAIT(wait);
-
-	prepare_to_wait(&iommu->vaddr_wait, &wait, TASK_KILLABLE);
-	mutex_unlock(&iommu->lock);
-	schedule();
-	mutex_lock(&iommu->lock);
-	finish_wait(&iommu->vaddr_wait, &wait);
-	if (kthread_should_stop() || !iommu->container_open ||
-	    fatal_signal_pending(current)) {
-		return -EFAULT;
-	}
-	return WAITED;
-}
-
-/*
- * Find dma struct and wait for its vaddr to be valid.  iommu lock is dropped
- * if the task waits, but is re-locked on return.  Return result in *dma_p.
- * Return 0 on success with no waiting, WAITED on success if waited, and -errno
- * on error.
- */
-static int vfio_find_dma_valid(struct vfio_iommu *iommu, dma_addr_t start,
-			       size_t size, struct vfio_dma **dma_p)
-{
-	int ret = 0;
-
-	do {
-		*dma_p = vfio_find_dma(iommu, start, size);
-		if (!*dma_p)
-			return -EINVAL;
-		else if (!(*dma_p)->vaddr_invalid)
-			return ret;
-		else
-			ret = vfio_wait(iommu);
-	} while (ret == WAITED);
-
-	return ret;
-}
-
-/*
- * Wait for all vaddr in the dma_list to become valid.  iommu lock is dropped
- * if the task waits, but is re-locked on return.  Return 0 on success with no
- * waiting, WAITED on success if waited, and -errno on error.
- */
-static int vfio_wait_all_valid(struct vfio_iommu *iommu)
-{
-	int ret = 0;
-
-	while (iommu->vaddr_invalid_count && ret >= 0)
-		ret = vfio_wait(iommu);
-
-	return ret;
-}
-
 /*
  * Attempt to pin pages.  We really don't want to track all the pfns and
  * the iommu can only map chunks of consecutive pfns anyway, so get the
@@ -851,7 +793,6 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
 	unsigned long remote_vaddr;
 	struct vfio_dma *dma;
 	bool do_accounting;
-	dma_addr_t iova;
 
 	if (!iommu || !pages)
 		return -EINVAL;
@@ -864,22 +805,6 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
 
 	mutex_lock(&iommu->lock);
 
-	/*
-	 * Wait for all necessary vaddr's to be valid so they can be used in
-	 * the main loop without dropping the lock, to avoid racing vs unmap.
-	 */
-again:
-	if (iommu->vaddr_invalid_count) {
-		for (i = 0; i < npage; i++) {
-			iova = user_iova + PAGE_SIZE * i;
-			ret = vfio_find_dma_valid(iommu, iova, PAGE_SIZE, &dma);
-			if (ret < 0)
-				goto pin_done;
-			if (ret == WAITED)
-				goto again;
-		}
-	}
-
 	/* Fail if no dma_umap notifier is registered */
 	if (list_empty(&iommu->device_list)) {
 		ret = -EINVAL;
@@ -895,6 +820,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
 
 	for (i = 0; i < npage; i++) {
 		unsigned long phys_pfn;
+		dma_addr_t iova;
 		struct vfio_pfn *vpfn;
 
 		iova = user_iova + PAGE_SIZE * i;
@@ -1181,10 +1107,8 @@ static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
 	put_task_struct(dma->task);
 	mmdrop(dma->mm);
 	vfio_dma_bitmap_free(dma);
-	if (dma->vaddr_invalid) {
+	if (dma->vaddr_invalid)
 		iommu->vaddr_invalid_count--;
-		wake_up_all(&iommu->vaddr_wait);
-	}
 	kfree(dma);
 	iommu->dma_avail++;
 }
@@ -1639,7 +1563,6 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
 				dma->vaddr_invalid = false;
 				iommu->vaddr_invalid_count--;
 			}
-			wake_up_all(&iommu->vaddr_wait);
 		}
 		goto out_unlock;
 	} else if (dma) {
@@ -1730,10 +1653,6 @@ static int vfio_iommu_replay(struct vfio_iommu *iommu,
 	unsigned long limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
 	int ret;
 
-	ret = vfio_wait_all_valid(iommu);
-	if (ret < 0)
-		return ret;
-
 	/* Arbitrarily pick the first domain in the list for lookups */
 	if (!list_empty(&iommu->domain_list))
 		d = list_first_entry(&iommu->domain_list,
@@ -2623,7 +2542,6 @@ static void *vfio_iommu_type1_open(unsigned long arg)
 	mutex_init(&iommu->lock);
 	mutex_init(&iommu->device_list_lock);
 	INIT_LIST_HEAD(&iommu->device_list);
-	init_waitqueue_head(&iommu->vaddr_wait);
 	iommu->pgsize_bitmap = PAGE_MASK;
 	INIT_LIST_HEAD(&iommu->emulated_iommu_groups);
 
@@ -3120,15 +3038,14 @@ static int vfio_iommu_type1_dma_rw_chunk(struct vfio_iommu *iommu,
 	struct vfio_dma *dma;
 	bool kthread = current->mm == NULL;
 	size_t offset;
-	int ret;
 
 	WARN_ON(iommu->vaddr_invalid_count);
 
 	*copied = 0;
 
-	ret = vfio_find_dma_valid(iommu, user_iova, 1, &dma);
-	if (ret < 0)
-		return ret;
+	dma = vfio_find_dma(iommu, user_iova, 1);
+	if (!dma)
+		return -EINVAL;
 
 	if ((write && !(dma->prot & IOMMU_WRITE)) ||
 			!(dma->prot & IOMMU_READ))
@@ -3230,7 +3147,6 @@ static void vfio_iommu_type1_notify(void *iommu_data,
 	mutex_lock(&iommu->lock);
 	iommu->container_open = false;
 	mutex_unlock(&iommu->lock);
-	wake_up_all(&iommu->vaddr_wait);
 }
 
 static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
-- 
1.8.3.1