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Commit 522e5cb7 authored by Joerg Roedel's avatar Joerg Roedel
Browse files

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: aafd8ba0 ('iommu/amd: Implement add_device and remove_device')
Cc: stable@vger.kernel.org # v4.2+
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 0caa7616

drivers/iommu/amd_iommu_init.c

+12 −2
Original line number Original line Diff line number Diff line
@@ -1568,13 +1568,23 @@ static int __init amd_iommu_init_pci(void) 
			break;

			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();

	init_device_table_dma();





	for_each_iommu(iommu)

	for_each_iommu(iommu)

		iommu_flush_all_caches(iommu);

		iommu_flush_all_caches(iommu);





	ret = amd_iommu_init_api();



	if (!ret)

	if (!ret)

		print_iommu_info();

		print_iommu_info();