[PATCH 7/7] Intel pci: Indicate 64-bit IOMMU passthrough available

[Mike Travis]

    Prior to these IOMMU patches, the passthrough option
    could not be used because it would cause the kernel to
    panic.  Provide an indication that a kernel is capable
    of handling passthrough mode through the introduction
    of a specific variable name.  This allows automatic
    configuration utilities to set the "iommu=pt" kernel
    cmdline option safely.

Signed-off-by: Mike Travis <travis@xxxxxxx>
Acked-by: Dimitri Sivanich <sivanich@xxxxxxx>
---
 drivers/pci/intel-iommu.c |    4 ++++
 1 file changed, 4 insertions(+)

--- linux.orig/drivers/pci/intel-iommu.c
+++ linux/drivers/pci/intel-iommu.c
@@ -390,6 +390,9 @@ static int dmar_map_gfx = 1;
 static int dmar_forcedac;
 static int intel_iommu_strict;
 
+/* specifically named variable that indicates "iommu=pt" is available */
+static int __initdata intel_iommu_64bit_pt;
+
 #define DUMMY_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-1))
 static DEFINE_SPINLOCK(device_domain_lock);
 static LIST_HEAD(device_domain_list);
@@ -425,6 +428,7 @@ static int __init intel_iommu_setup(char
 		while (*str == ',')
 			str++;
 	}
+	intel_iommu_64bit_pt = 1;
 	return 0;
 }
 __setup("intel_iommu=", intel_iommu_setup);

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