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authorBaoquan He <bhe@redhat.com>2017-08-09 11:33:42 +0300
committerJoerg Roedel <jroedel@suse.de>2017-08-15 19:14:40 +0300
commitb336781b82cc12c7940a2b1c806fbe7f78ecd72a (patch)
treeaf88008707223a08b2f7a44d43d5c8aa11baa00a /drivers/iommu/amd_iommu_init.c
parentdf3f7a6e8e855e4ff533508807cd7c3723faa51f (diff)
downloadlinux-b336781b82cc12c7940a2b1c806fbe7f78ecd72a.tar.xz
iommu/amd: Allocate memory below 4G for dev table if translation pre-enabled
AMD pointed out it's unsafe to update the device-table while iommu is enabled. It turns out that device-table pointer update is split up into two 32bit writes in the IOMMU hardware. So updating it while the IOMMU is enabled could have some nasty side effects. The safe way to work around this is to always allocate the device-table below 4G, including the old device-table in normal kernel and the device-table used for copying the content of the old device-table in kdump kernel. Meanwhile we need check if the address of old device-table is above 4G because it might has been touched accidentally in corrupted 1st kernel. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu/amd_iommu_init.c')
-rw-r--r--drivers/iommu/amd_iommu_init.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index d08ad74b0928..c348732f27d7 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -885,11 +885,15 @@ static bool copy_device_table(void)
}
old_devtb_phys = entry & PAGE_MASK;
+ if (old_devtb_phys >= 0x100000000ULL) {
+ pr_err("The address of old device table is above 4G, not trustworthy!/n");
+ return false;
+ }
old_devtb = memremap(old_devtb_phys, dev_table_size, MEMREMAP_WB);
if (!old_devtb)
return false;
- gfp_flag = GFP_KERNEL | __GFP_ZERO;
+ gfp_flag = GFP_KERNEL | __GFP_ZERO | GFP_DMA32;
old_dev_tbl_cpy = (void *)__get_free_pages(gfp_flag,
get_order(dev_table_size));
if (old_dev_tbl_cpy == NULL) {
@@ -2432,7 +2436,8 @@ static int __init early_amd_iommu_init(void)
/* Device table - directly used by all IOMMUs */
ret = -ENOMEM;
- amd_iommu_dev_table = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+ amd_iommu_dev_table = (void *)__get_free_pages(
+ GFP_KERNEL | __GFP_ZERO | GFP_DMA32,
get_order(dev_table_size));
if (amd_iommu_dev_table == NULL)
goto out;