iommu/amd: Move gart fallback to amd_iommu_init

The fallback to the GART driver in the case amd_iommu doesn't work was
executed in a function called free_iommu_resources, which didn't really
make sense. This was even being called twice if amd_iommu=off was
specified on the command line.

The only complication is that it needs to be verified that amd_iommu has
fully relinquished control by calling free_iommu_resources and emptying
the amd_iommu_list.

Signed-off-by: Kevin Mitchell <kevmitch@arista.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/amd_iommu_init.c

@@ -2340,15 +2340,6 @@ static void __init free_iommu_resources(void)
 	amd_iommu_dev_table = NULL;
 
 	free_iommu_all();
-
-#ifdef CONFIG_GART_IOMMU
-	/*
-	 * We failed to initialize the AMD IOMMU - try fallback to GART
-	 * if possible.
-	 */
-	gart_iommu_init();
-
-#endif
 }
 
 /* SB IOAPIC is always on this device in AMD systems */
@@ -2767,6 +2758,16 @@ static int __init amd_iommu_init(void)
 		}
 	}
 
+#ifdef CONFIG_GART_IOMMU
+	if (ret && list_empty(&amd_iommu_list)) {
+		/*
+		 * We failed to initialize the AMD IOMMU - try fallback
+		 * to GART if possible.
+		 */
+		gart_iommu_init();
+	}
+#endif
+
 	for_each_iommu(iommu)
 		amd_iommu_debugfs_setup(iommu);