[PATCH 1/1] iommu/vt-d: Flush IOTLB for untrusted device in time

From: Lu Baolu
Date: Fri Apr 12 2019 - 00:32:30 EST


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@xxxxxxxxx>
Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Tested-by: Xu Pengfei <pengfei.xu@xxxxxxxxx>
Tested-by: Mika Westerberg <mika.westerberg@xxxxxxxxx>
---
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 c137f0f2cf49..3d504b685dd8 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3732,10 +3732,14 @@ 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;

+ if (dev_is_pci(dev))
+ pdev = to_pci_dev(dev);
+
domain = find_domain(dev);
BUG_ON(!domain);

@@ -3751,7 +3755,7 @@ static void intel_unmap(struct device *dev, dma_addr_t dev_addr, size_t size)

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 */
--
2.17.1