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>

2 files changed, 34 insertions, 4 deletions

diff --git a/arch/x86/kernel/e820_64.c b/arch/x86/kernel/e820_64.c
index 57616865d8a0..1ca228b06a20 100644
--- a/arch/x86/kernel/e820_64.c
+++ b/arch/x86/kernel/e820_64.c
@@ -729,3 +729,22 @@ __init void e820_setup_gap(void)
         printk(KERN_INFO "Allocating PCI resources starting at %lx (gap: %lx:%lx)\n",
                 pci_mem_start, gapstart, gapsize);
 }
+
+int __init arch_get_ram_range(int slot, u64 *addr, u64 *size)
+{
+        int i;
+
+        if (slot < 0 || slot >= e820.nr_map)
+                return -1;
+        for (i = slot; i < e820.nr_map; i++) {
+                if (e820.map[i].type != E820_RAM)
+                        continue;
+                break;
+        }
+        if (i == e820.nr_map || e820.map[i].addr > (max_pfn << PAGE_SHIFT))
+                return -1;
+        *addr = e820.map[i].addr;
+        *size = min_t(u64, e820.map[i].size + e820.map[i].addr,
+                max_pfn << PAGE_SHIFT) - *addr;
+        return i + 1;
+}
diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index 5c9aaed589a5..5cf941774347 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"