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authorMika Westerberg <mika.westerberg@linux.intel.com>2018-10-29 13:47:08 +0300
committerMika Westerberg <mika.westerberg@linux.intel.com>2018-12-05 12:01:56 +0300
commitfb58fdcd295b914ece1d829b24df00a17a9624bc (patch)
tree0e2800c7216e4ed3f57abecc343bec5ac5dad7bd /drivers/iommu
parent89a6079df791aeace2044ea93be1b397195824ec (diff)
downloadlinux-fb58fdcd295b914ece1d829b24df00a17a9624bc.tar.bz2
iommu/vt-d: Do not enable ATS for untrusted devices
Currently Linux automatically enables ATS (Address Translation Service) for any device that supports it (and IOMMU is turned on). ATS is used to accelerate DMA access as the device can cache translations locally so there is no need to do full translation on IOMMU side. However, as pointed out in [1] ATS can be used to bypass IOMMU based security completely by simply sending PCIe read/write transaction with AT (Address Translation) field set to "translated". To mitigate this modify the Intel IOMMU code so that it does not enable ATS for any device that is marked as being untrusted. In case this turns out to cause performance issues we may selectively allow ATS based on user decision but currently use big hammer and disable it completely to be on the safe side. [1] https://www.repository.cam.ac.uk/handle/1810/274352 Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Ashok Raj <ashok.raj@intel.com> Reviewed-by: Joerg Roedel <jroedel@suse.de> Acked-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu')
-rw-r--r--drivers/iommu/intel-iommu.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 30e8584137f5..adc2c9619e56 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1473,7 +1473,8 @@ static void iommu_enable_dev_iotlb(struct device_domain_info *info)
if (info->pri_supported && !pci_reset_pri(pdev) && !pci_enable_pri(pdev, 32))
info->pri_enabled = 1;
#endif
- if (info->ats_supported && !pci_enable_ats(pdev, VTD_PAGE_SHIFT)) {
+ if (!pdev->untrusted && info->ats_supported &&
+ !pci_enable_ats(pdev, VTD_PAGE_SHIFT)) {
info->ats_enabled = 1;
domain_update_iotlb(info->domain);
info->ats_qdep = pci_ats_queue_depth(pdev);