| From 522e5cb76d0663c88f96b6a8301451c8efa37207 Mon Sep 17 00:00:00 2001 |
| From: Joerg Roedel <jroedel@suse.de> |
| Date: Fri, 1 Jul 2016 16:42:55 +0200 |
| Subject: iommu/amd: Fix unity mapping initialization race |
| |
| From: Joerg Roedel <jroedel@suse.de> |
| |
| commit 522e5cb76d0663c88f96b6a8301451c8efa37207 upstream. |
| |
| 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') |
| Signed-off-by: Joerg Roedel <jroedel@suse.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/iommu/amd_iommu_init.c | 14 ++++++++++++-- |
| 1 file changed, 12 insertions(+), 2 deletions(-) |
| |
| --- a/drivers/iommu/amd_iommu_init.c |
| +++ b/drivers/iommu/amd_iommu_init.c |
| @@ -1363,13 +1363,23 @@ static int __init amd_iommu_init_pci(voi |
| 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(); |
| |
