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authorJoerg Roedel <jroedel@suse.de>2016-07-01 16:42:55 +0200
committerJoerg Roedel <jroedel@suse.de>2016-07-06 18:04:55 +0200
commit522e5cb76d0663c88f96b6a8301451c8efa37207 (patch)
treeacdc27a0aaf522cc2f7441cbcbe11251e3029679 /drivers/iommu
parent0caa7616a6aca449dd68b58cb29bd491d296c2d5 (diff)
downloadop-kernel-dev-522e5cb76d0663c88f96b6a8301451c8efa37207.zip
op-kernel-dev-522e5cb76d0663c88f96b6a8301451c8efa37207.tar.gz
iommu/amd: Fix unity mapping initialization race
There is a race condition in the AMD IOMMU init code that causes requested unity mappings to be blocked by the IOMMU for a short period of time. This results on boot failures and IO_PAGE_FAULTs on some machines. Fix this by making sure the unity mappings are installed before all other DMA is blocked. Fixes: aafd8ba0ca74 ('iommu/amd: Implement add_device and remove_device') Cc: stable@vger.kernel.org # v4.2+ Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu')
-rw-r--r--drivers/iommu/amd_iommu_init.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index d091def..59741ea 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -1568,13 +1568,23 @@ static int __init amd_iommu_init_pci(void)
break;
}
+ /*
+ * Order is important here to make sure any unity map requirements are
+ * fulfilled. The unity mappings are created and written to the device
+ * table during the amd_iommu_init_api() call.
+ *
+ * After that we call init_device_table_dma() to make sure any
+ * uninitialized DTE will block DMA, and in the end we flush the caches
+ * of all IOMMUs to make sure the changes to the device table are
+ * active.
+ */
+ ret = amd_iommu_init_api();
+
init_device_table_dma();
for_each_iommu(iommu)
iommu_flush_all_caches(iommu);
- ret = amd_iommu_init_api();
-
if (!ret)
print_iommu_info();
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