PCI: Add support for PASID capability

Devices supporting Process Address Space Identifiers
(PASIDs) can use an IOMMU to access multiple IO address
spaces at the same time. A PCIe device indicates support for
this feature by implementing the PASID capability. This
patch adds support for the capability to the Linux kernel.

Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index fb1e9707..cec6606 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -94,6 +94,19 @@
 
 	  If unsure, say N.
 
+config PCI_PASID
+	bool "PCI PASID support"
+	depends on PCI
+	select PCI_ATS
+	help
+	  Process Address Space Identifiers (PASIDs) can be used by PCI devices
+	  to access more than one IO address space at the same time. To make
+	  use of this feature an IOMMU is required which also supports PASIDs.
+	  Select this option if you have such an IOMMU and want to compile the
+	  driver for it into your kernel.
+
+	  If unsure, say N.
+
 config PCI_IOAPIC
 	bool
 	depends on PCI