linux-kernel - [PATCH] [2/12] x86_64: Calgary - Fix mis-handled PCI topology

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Date:	Thu,  9 Aug 2007 14:41:29 +0200 (CEST)
From:	Andi Kleen <ak@...e.de>
To:	bernarde@...ibm.com, patches@...-64.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] [2/12] x86_64: Calgary - Fix mis-handled PCI topology


From: Murillo Fernandes Bernardes <bernarde@...ibm.com>
Subject: x86-64: Calgary - Fix mis-handled PCI topology

Current code assumed that devices were directly connected to a Calgary
bridge, as it tried to get the iommu table directly from the parent bus 
controller.

When we have another bridge between the Calgary/CalIOC2 bridge and the 
device we should look upwards until we get to the top (Calgary/CalIOC2 
bridge), where the iommu table resides.

Signed-off-by: Murillo Fernandes Bernardes <mfb@...ibm.com>
Signed-off-by: Muli Ben-Yehuda <muli@...ibm.com>
Signed-off-by: Andi Kleen <ak@...e.de>

 arch/x86_64/kernel/pci-calgary.c |   13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

Index: linux/arch/x86_64/kernel/pci-calgary.c
===================================================================
--- linux.orig/arch/x86_64/kernel/pci-calgary.c
+++ linux/arch/x86_64/kernel/pci-calgary.c
@@ -367,16 +367,15 @@ static inline struct iommu_table *find_i
 
 	pdev = to_pci_dev(dev);
 
-	/* is the device behind a bridge? */
-	if (unlikely(pdev->bus->parent))
-		pbus = pdev->bus->parent;
-	else
-		pbus = pdev->bus;
+	pbus = pdev->bus;
+
+	/* is the device behind a bridge? Look for the root bus */
+	while (pbus->parent)
+		pbus = pbus->parent;
 
 	tbl = pci_iommu(pbus);
 
-	BUG_ON(pdev->bus->parent &&
-	       (tbl->it_busno != pdev->bus->parent->number));
+	BUG_ON(tbl && (tbl->it_busno != pbus->number));
 
 	return tbl;
 }
-
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