From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Joerg Roedel Subject: [PATCH 4.6 091/203] iommu/amd: Fix unity mapping initialization race Date: Mon, 25 Jul 2016 13:55:06 -0700 Message-Id: <20160725203433.059462485@linuxfoundation.org> In-Reply-To: <20160725203429.221747288@linuxfoundation.org> References: <20160725203429.221747288@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Joerg Roedel 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 Signed-off-by: Greg Kroah-Hartman --- 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();