[PATCH] x86_64: Calgary IOMMU - introduce iommu_detected

swiotlb relies on the gart specific iommu_aperture variable to know if
we discovered a hardware IOMMU before swiotlb initialization.  Introduce
iommu_detected to do the same thing, but in a HW IOMMU neutral manner,
in preparation for adding the Calgary HW IOMMU.

Signed-Off-By: Muli Ben-Yehuda <muli@il.ibm.com>
Signed-Off-By: Jon Mason <jdmason@us.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/pci-gart.c b/arch/x86_64/kernel/pci-gart.c
index 82a346e6e2e4..4f67957d2b42 100644
--- a/arch/x86_64/kernel/pci-gart.c
+++ b/arch/x86_64/kernel/pci-gart.c
@@ -597,6 +597,10 @@ static int __init pci_iommu_init(void)
         if (swiotlb)
                 return -ENODEV;
 
+        /* Did we detect a different HW IOMMU? */
+        if (iommu_detected && !iommu_aperture)
+                return -1;
+
         if (no_iommu ||
             (!force_iommu && end_pfn <= MAX_DMA32_PFN) ||
             !iommu_aperture ||