[PATCH 2/3] iommu/amd: move gart fallback to amd_iommu_init

Kevin Mitchell via iommu
2019-05-17T01:00:30Z

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>
---
drivers/iommu/amd_iommu_init.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 3798d7303c99..5f3df5ae6ba8 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -2345,15 +2345,6 @@ 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 */
@@ -2774,6 +2765,16 @@ 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);