[PATCH 5.1 102/155] iommu/vt-d: Flush IOTLB for untrusted device in time

Greg Kroah-Hartman
2019-06-13T16:01:20Z

[ Upstream commit f7b0c4ce8cb3c09cb3cbfc0c663268bf99e5fa9c ]

By default, for performance consideration, Intel IOMMU
driver won't flush IOTLB immediately after a buffer is
unmapped. It schedules a thread and flushes IOTLB in a
batched mode. This isn't suitable for untrusted device
since it still can access the memory even if it isn't
supposed to do so.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Xu Pengfei <pengfei.xu@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/iommu/intel-iommu.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index cb656f503604..0feb3f70da16 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3736,6 +3736,7 @@ static void intel_unmap(struct device *dev, dma_addr_t dev_addr, size_t size)
unsigned long iova_pfn;
struct intel_iommu *iommu;
struct page *freelist;
+ struct pci_dev *pdev = NULL;

if (iommu_no_mapping(dev))
return;
@@ -3751,11 +3752,14 @@ static void intel_unmap(struct device *dev, dma_addr_t dev_addr, size_t size)
start_pfn = mm_to_dma_pfn(iova_pfn);
last_pfn = start_pfn + nrpages - 1;

+ if (dev_is_pci(dev))
+ pdev = to_pci_dev(dev);
+
dev_dbg(dev, "Device unmapping: pfn %lx-%lx\n", start_pfn, last_pfn);

freelist = domain_unmap(domain, start_pfn, last_pfn);

- if (intel_iommu_strict) {
+ if (intel_iommu_strict || (pdev && pdev->untrusted)) {
iommu_flush_iotlb_psi(iommu, domain, start_pfn,
nrpages, !freelist, 0);
/* free iova */
--
2.20.1