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Subject[tip:x86/mm] iommu/amd: Remap the IOMMU device table with the memory encryption mask for kdump
Commit-ID:  8780158cf977ea5f9912931a30b3d575b36dba22
Gitweb: https://git.kernel.org/tip/8780158cf977ea5f9912931a30b3d575b36dba22
Author: Lianbo Jiang <lijiang@redhat.com>
AuthorDate: Sun, 30 Sep 2018 11:10:32 +0800
Committer: Borislav Petkov <bp@suse.de>
CommitDate: Sat, 6 Oct 2018 12:08:24 +0200

iommu/amd: Remap the IOMMU device table with the memory encryption mask for kdump

The kdump kernel copies the IOMMU device table from the old device table
which is encrypted when SME is enabled in the first kernel. So remap the
old device table with the memory encryption mask in the kdump kernel.

[ bp: Massage commit message. ]

Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
Cc: kexec@lists.infradead.org
Cc: tglx@linutronix.de
Cc: mingo@redhat.com
Cc: hpa@zytor.com
Cc: akpm@linux-foundation.org
Cc: dan.j.williams@intel.com
Cc: bhelgaas@google.com
Cc: baiyaowei@cmss.chinamobile.com
Cc: tiwai@suse.de
Cc: brijesh.singh@amd.com
Cc: dyoung@redhat.com
Cc: bhe@redhat.com
Link: https://lkml.kernel.org/r/20180930031033.22110-4-lijiang@redhat.com
---
drivers/iommu/amd_iommu_init.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 84b3e4445d46..3931c7de7c69 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -902,12 +902,22 @@ static bool copy_device_table(void)
}
}

- old_devtb_phys = entry & PAGE_MASK;
+ /*
+ * When SME is enabled in the first kernel, the entry includes the
+ * memory encryption mask(sme_me_mask), we must remove the memory
+ * encryption mask to obtain the true physical address in kdump kernel.
+ */
+ old_devtb_phys = __sme_clr(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);
+ old_devtb = (sme_active() && is_kdump_kernel())
+ ? (__force void *)ioremap_encrypted(old_devtb_phys,
+ dev_table_size)
+ : memremap(old_devtb_phys, dev_table_size, MEMREMAP_WB);
+
if (!old_devtb)
return false;

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