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>

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;
+}