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iommu/amd: Fix unity mapping initialization race

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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>
This commit is contained in:
Joerg Roedel 2016-07-01 16:42:55 +02:00 committed by Greg Kroah-Hartman
parent 72803a72a6
commit e205592b31
1 changed files with 12 additions and 2 deletions
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14
drivers/iommu/amd_iommu_init.c
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@ -1363,13 +1363,23 @@ 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();