From f9423606ade08653dd8a43334f0a7fb45504c5cc Mon Sep 17 00:00:00 2001
From: Julian Stecklina <jsteckli@os.inf.tu-dresden.de>
Date: Wed, 9 Oct 2013 10:03:52 +0200
Subject: [PATCH] iommu/vt-d: Fixed interaction of VFIO_IOMMU_MAP_DMA with
 IOMMU address limits

The BUG_ON in drivers/iommu/intel-iommu.c:785 can be triggered from userspace via
VFIO by calling the VFIO_IOMMU_MAP_DMA ioctl on a vfio device with any address
beyond the addressing capabilities of the IOMMU. The problem is that the ioctl code
calls iommu_iova_to_phys before it calls iommu_map. iommu_map handles the case that
it gets addresses beyond the addressing capabilities of its IOMMU.
intel_iommu_iova_to_phys does not.

This patch fixes iommu_iova_to_phys to return NULL for addresses beyond what the
IOMMU can handle. This in turn causes the ioctl call to fail in iommu_map and
(correctly) return EFAULT to the user with a helpful warning message in the kernel
log.

Signed-off-by: Julian Stecklina <jsteckli@os.inf.tu-dresden.de>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>
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