iommu/vt-d: Clear Page Request Overflow fault bit

Currently Page Request Overflow bit in IOMMU Fault Status register
is not cleared. Not clearing this bit would mean that any  future
page-request is going to be automatically dropped by IOMMU.

Suggested-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 1ea7cd5..9a7ffd1 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -1679,7 +1679,8 @@ irqreturn_t dmar_fault(int irq, void *dev_id)
 		raw_spin_lock_irqsave(&iommu->register_lock, flag);
 	}
 
-	writel(DMA_FSTS_PFO | DMA_FSTS_PPF, iommu->reg + DMAR_FSTS_REG);
+	writel(DMA_FSTS_PFO | DMA_FSTS_PPF | DMA_FSTS_PRO,
+	       iommu->reg + DMAR_FSTS_REG);
 
 unlock_exit:
 	raw_spin_unlock_irqrestore(&iommu->register_lock, flag);