Intel IOMMU: Iommu Gfx workaround

When we fix all the opensource gfx drivers to use the DMA api's, at that time
we can yank this config options out.

[jengelh@computergmbh.de: Kconfig fixes]
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: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 4 deletions

diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index 5c9aaed..5cf9417 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -755,11 +755,22 @@ config DMAR
 	depends on PCI_MSI && ACPI && EXPERIMENTAL
 	default y
 	help
-	  DMA remapping(DMAR) devices support enables independent address
-	  translations for Direct Memory Access(DMA) from Devices.
+	  DMA remapping (DMAR) devices support enables independent address
+	  translations for Direct Memory Access (DMA) from devices.
 	  These DMA remapping devices are reported via ACPI tables
-	  and includes pci device scope covered by these DMA
-	  remapping device.
+	  and include PCI device scope covered by these DMA
+	  remapping devices.
+
+config DMAR_GFX_WA
+	bool "Support for Graphics workaround"
+	depends on DMAR
+	default y
+	help
+	 Current Graphics drivers tend to use physical address
+	 for DMA and avoid using DMA APIs. Setting this config
+	 option permits the IOMMU driver to set a unity map for
+	 all the OS-visible memory. Hence the driver can continue
+	 to use physical addresses for DMA.
 
 source "drivers/pci/pcie/Kconfig"