Intel IOMMU: PCI generic helper function

When devices are under a p2p bridge, upstream transactions get replaced by the
device id of the bridge as it owns the PCIE transaction.  Hence its necessary
to setup translations on behalf of the bridge as well.  Due to this limitation
all devices under a p2p share the same domain in a DMAR.

We just cache the type of device, if its a native PCIe device
or not for later use.

[akpm@linux-foundation.org: BUG_ON -> WARN_ON+recover]
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Muli Ben-Yehuda <muli@il.ibm.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index c6e79d0..b001b59 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -14,6 +14,40 @@
 #include "pci.h"
 
 DECLARE_RWSEM(pci_bus_sem);
+/*
+ * find the upstream PCIE-to-PCI bridge of a PCI device
+ * if the device is PCIE, return NULL
+ * if the device isn't connected to a PCIE bridge (that is its parent is a
+ * legacy PCI bridge and the bridge is directly connected to bus 0), return its
+ * parent
+ */
+struct pci_dev *
+pci_find_upstream_pcie_bridge(struct pci_dev *pdev)
+{
+	struct pci_dev *tmp = NULL;
+
+	if (pdev->is_pcie)
+		return NULL;
+	while (1) {
+		if (!pdev->bus->self)
+			break;
+		pdev = pdev->bus->self;
+		/* a p2p bridge */
+		if (!pdev->is_pcie) {
+			tmp = pdev;
+			continue;
+		}
+		/* PCI device should connect to a PCIE bridge */
+		if (pdev->pcie_type != PCI_EXP_TYPE_PCI_BRIDGE) {
+			/* Busted hardware? */
+			WARN_ON_ONCE(1);
+			return NULL;
+		}
+		return pdev;
+	}
+
+	return tmp;
+}
 
 static struct pci_bus *pci_do_find_bus(struct pci_bus *bus, unsigned char busnr)
 {