From: Joerg Roedel <joerg.roedel@amd.com>
Date: Mon, 31 May 2010 13:05:20 +0000 (+0200)
Subject: x86/amd-iommu: Fall back to GART if initialization fails
X-Git-Tag: v2.6.33.6~96
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0ac5ad9b26e8879728141ad76b56a8b9cc72cd98;p=thirdparty%2Fkernel%2Fstable.git

x86/amd-iommu: Fall back to GART if initialization fails

commit d7f0776975334070a93370ae048fda0c31a91c38 upstream.

This patch implements a fallback to the GART IOMMU if this
is possible and the AMD IOMMU initialization failed.
Otherwise the fallback would be nommu which is very
problematic on machines with more than 4GB of memory or
swiotlb which hurts io-performance.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 2e775169bdf0b..bbef34ed4d028 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -2256,10 +2256,6 @@ int __init amd_iommu_init_dma_ops(void)
 
 	iommu_detected = 1;
 	swiotlb = 0;
-#ifdef CONFIG_GART_IOMMU
-	gart_iommu_aperture_disabled = 1;
-	gart_iommu_aperture = 0;
-#endif
 
 	/* Make the driver finally visible to the drivers */
 	dma_ops = &amd_iommu_dma_ops;
diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index fdce84d494592..86a5a1178076b 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -1340,6 +1340,15 @@ free:
 
 	free_unity_maps();
 
+#ifdef CONFIG_GART_IOMMU
+	/*
+	 * We failed to initialize the AMD IOMMU - try fallback to GART
+	 * if possible.
+	 */
+	gart_iommu_init();
+
+#endif
+
 	goto out;
 }