[PATCH 3/4] iommu/vt-d: Handle RMRR with PCI bridge device scopes

[Eric Auger <eric.auger@redhat.com>]

When reading the vtd specification and especially the
Reserved Memory Region Reporting Structure chapter,
it is not obvious a device scope element cannot be a
PCI-PCI bridge, in which case all downstream ports are
likely to access the reserved memory region. Let's handle
this case in device_has_rmrr.

Fixes: ea2447f700ca ("intel-iommu: Prevent devices with RMRRs from being placed into SI Domain")

Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 drivers/iommu/intel-iommu.c | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index e2134b13c9ae..89d82a1d50b1 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -736,12 +736,31 @@ static int iommu_dummy(struct device *dev)
 	return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;
 }
 
+static bool
+is_downstream_to_pci_bridge(struct device *deva, struct device *devb)
+{
+	struct pci_dev *pdeva, *pdevb;
+
+	if (!dev_is_pci(deva) || !dev_is_pci(devb))
+		return false;
+
+	pdeva = to_pci_dev(deva);
+	pdevb = to_pci_dev(devb);
+
+	if (pdevb->subordinate &&
+	    pdevb->subordinate->number <= pdeva->bus->number &&
+	    pdevb->subordinate->busn_res.end >= pdeva->bus->number)
+		return true;
+
+	return false;
+}
+
 static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn)
 {
 	struct dmar_drhd_unit *drhd = NULL;
 	struct intel_iommu *iommu;
 	struct device *tmp;
-	struct pci_dev *ptmp, *pdev = NULL;
+	struct pci_dev *pdev = NULL;
 	u16 segment = 0;
 	int i;
 
@@ -787,13 +806,7 @@ static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devf
 				goto out;
 			}
 
-			if (!pdev || !dev_is_pci(tmp))
-				continue;
-
-			ptmp = to_pci_dev(tmp);
-			if (ptmp->subordinate &&
-			    ptmp->subordinate->number <= pdev->bus->number &&
-			    ptmp->subordinate->busn_res.end >= pdev->bus->number)
+			if (is_downstream_to_pci_bridge(dev, tmp))
 				goto got_pdev;
 		}
 
@@ -2886,7 +2899,8 @@ static bool device_has_rmrr(struct device *dev)
 		 */
 		for_each_active_dev_scope(rmrr->devices,
 					  rmrr->devices_cnt, i, tmp)
-			if (tmp == dev) {
+			if (tmp == dev ||
+			    is_downstream_to_pci_bridge(dev, tmp)) {
 				rcu_read_unlock();
 				return true;
 			}
-- 
2.20.1