From 5a5394d0e833a794b6055f9a7cd1726ecbe13d14 Mon Sep 17 00:00:00 2001
From: Alex Williamson <alex.williamson@redhat.com>
Date: Wed, 30 May 2012 14:19:43 -0600
Subject: [PATCH] --- yaml --- r: 316583 b: refs/heads/master c:
 783f157bc5a7fa30ee17b4099b27146bd1b68af4 h: refs/heads/master i:   316581:
 a1da2b465c68f60973e389a745cef0ba2e85aae6   316579:
 df3f74e6c2c275319d0355e4ca3f01aff1da8c78   316575:
 5ac7f0e3f8e62802a58bca777a2fea835a0bd032 v: v3

---
 [refs]                            |  2 +-
 trunk/drivers/iommu/intel-iommu.c | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 3f92614b3b6e..941b6107f1b7 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 664b600331128146d8ddd3e004defe23ba5c47dc
+refs/heads/master: 783f157bc5a7fa30ee17b4099b27146bd1b68af4
diff --git a/trunk/drivers/iommu/intel-iommu.c b/trunk/drivers/iommu/intel-iommu.c
index 4a434528cd1c..ebf2b310cdde 100644
--- a/trunk/drivers/iommu/intel-iommu.c
+++ b/trunk/drivers/iommu/intel-iommu.c
@@ -4090,6 +4090,14 @@ static int intel_iommu_domain_has_cap(struct iommu_domain *domain,
 	return 0;
 }
 
+static void swap_pci_ref(struct pci_dev **from, struct pci_dev *to)
+{
+	pci_dev_put(*from);
+	*from = to;
+}
+
+#define REQ_ACS_FLAGS	(PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF)
+
 static int intel_iommu_add_device(struct device *dev)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
@@ -4112,6 +4120,23 @@ static int intel_iommu_add_device(struct device *dev)
 	} else
 		dma_pdev = pci_dev_get(pdev);
 
+	swap_pci_ref(&dma_pdev, pci_get_dma_source(dma_pdev));
+
+	if (dma_pdev->multifunction &&
+	    !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS))
+		swap_pci_ref(&dma_pdev,
+			     pci_get_slot(dma_pdev->bus,
+					  PCI_DEVFN(PCI_SLOT(dma_pdev->devfn),
+					  0)));
+
+	while (!pci_is_root_bus(dma_pdev->bus)) {
+		if (pci_acs_path_enabled(dma_pdev->bus->self,
+					 NULL, REQ_ACS_FLAGS))
+			break;
+
+		swap_pci_ref(&dma_pdev, pci_dev_get(dma_pdev->bus->self));
+	}
+
 	group = iommu_group_get(&dma_pdev->dev);
 	pci_dev_put(dma_pdev);
 	if (!group) {