iommu/amd: use handle_mm_fault directly

This could be useful for debug in the future if we want to track
major/minor faults more closely, and also avoids the put_page trick we
used with gup.

In order to do this, we also track the task struct in the PASID state
structure.  This lets us update the appropriate task stats after the fault
has been handled, and may aid with debug in the future as well.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: NOded Gabbay <oded.gabbay@amd.com>
Cc: Joerg Roedel <jroedel@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/iommu/amd_iommu_v2.c

@@ -513,24 +513,15 @@ static void finish_pri_tag(struct device_state *dev_state,
 	spin_unlock_irqrestore(&pasid_state->lock, flags);
 }
 
-static void do_fault(struct work_struct *work)
+static void handle_fault_error(struct fault *fault)
 {
-	struct fault *fault = container_of(work, struct fault, work);
-	int npages, write;
-	struct page *page;
-
-	write = !!(fault->flags & PPR_FAULT_WRITE);
-
-	down_read(&fault->state->mm->mmap_sem);
-	npages = get_user_pages(NULL, fault->state->mm,
-				fault->address, 1, write, 0, &page, NULL);
-	up_read(&fault->state->mm->mmap_sem);
-
-	if (npages == 1) {
-		put_page(page);
-	} else if (fault->dev_state->inv_ppr_cb) {
 	int status;
 
+	if (!fault->dev_state->inv_ppr_cb) {
+		set_pri_tag_status(fault->state, fault->tag, PPR_INVALID);
+		return;
+	}
+
 	status = fault->dev_state->inv_ppr_cb(fault->dev_state->pdev,
 					      fault->pasid,
 					      fault->address,
@@ -548,10 +539,41 @@ static void do_fault(struct work_struct *work)
 	default:
 		BUG();
 	}
-	} else {
-		set_pri_tag_status(fault->state, fault->tag, PPR_INVALID);
+}
+
+static void do_fault(struct work_struct *work)
+{
+	struct fault *fault = container_of(work, struct fault, work);
+	struct mm_struct *mm;
+	struct vm_area_struct *vma;
+	u64 address;
+	int ret, write;
+
+	write = !!(fault->flags & PPR_FAULT_WRITE);
+
+	mm = fault->state->mm;
+	address = fault->address;
+
+	down_read(&mm->mmap_sem);
+	vma = find_extend_vma(mm, address);
+	if (!vma || address < vma->vm_start) {
+		/* failed to get a vma in the right range */
+		up_read(&mm->mmap_sem);
+		handle_fault_error(fault);
+		goto out;
 	}
 
+	ret = handle_mm_fault(mm, vma, address, write);
+	if (ret & VM_FAULT_ERROR) {
+		/* failed to service fault */
+		up_read(&mm->mmap_sem);
+		handle_fault_error(fault);
+		goto out;
+	}
+
+	up_read(&mm->mmap_sem);
+
+out:
 	finish_pri_tag(fault->dev_state, fault->state, fault->tag);
 
 	put_pasid_state(fault->state);