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

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Date:   Fri, 12 Apr 2019 12:26:13 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     David Woodhouse <dwmw2@...radead.org>,
        Joerg Roedel <joro@...tes.org>
Cc:     ashok.raj@...el.com, jacob.jun.pan@...el.com, kevin.tian@...el.com,
        mika.westerberg@...ux.intel.com, pengfei.xu@...el.com,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: [PATCH 1/1] iommu/vt-d: Flush IOTLB for untrusted device in time

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@...el.com>
Cc: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
Tested-by: Xu Pengfei <pengfei.xu@...el.com>
Tested-by: Mika Westerberg <mika.westerberg@...el.com>
---
 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