[PATCH] iommu/vt-d: Do not dump pasid table entries in kdump kernel
From: Zelin Deng
Date: Wed Jan 19 2022 - 04:07:47 EST
In kdump kernel PASID translations won't be copied from previous kernel
even if scalable-mode is enabled, so pages of PASID translations are
non-present in kdump kernel. Attempt to access those address will cause
PF fault:
[ 13.396476] DMAR: DRHD: handling fault status reg 3
[ 13.396478] DMAR: [DMA Read NO_PASID] Request device [81:00.0] fault addr 0xffffd000 [fault reason 0x59] SM: Present bit in PA$
[ 13.396480] DMAR: Dump dmar5 table entries for IOVA 0xffffd000
[ 13.396481] DMAR: scalable mode root entry: hi 0x0000000000000000, low 0x00000000460d1001
[ 13.396482] DMAR: context entry: hi 0x0000000000000008, low 0x00000010c4237401
[ 13.396485] BUG: unable to handle page fault for address: ff110010c4237000
[ 13.396486] #PF: supervisor read access in kernel mode
[ 13.396487] #PF: error_code(0x0000) - not-present page
[ 13.396488] PGD 5d201067 P4D 5d202067 PUD 0
[ 13.396490] Oops: 0000 [#1] PREEMPT SMP NOPTI
[ 13.396491] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.16.0-rc6-next-20211224+ #6
[ 13.396493] Hardware name: Intel Corporation EAGLESTREAM/EAGLESTREAM, BIOS EGSDCRB1.86B.0067.D12.2110190950 10/19/2021
[ 13.396494] RIP: 0010:dmar_fault_dump_ptes+0x13b/0x295
Hence skip dumping pasid table entries if in kdump kernel.
Fixes: 914ff7719e8a (“iommu/vt-d: Dump DMAR translation structure when DMA fault occurs”)
Signed-off-by: Zelin Deng <zelin.deng@xxxxxxxxxxxxxxxxx>
---
drivers/iommu/intel/iommu.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 92fea3fb..f0134cf 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1074,6 +1074,12 @@ void dmar_fault_dump_ptes(struct intel_iommu *iommu, u16 source_id,
if (!sm_supported(iommu))
goto pgtable_walk;
+ /* PASID translations is not copied, skip dumping pasid table entries
+ * otherwise non-present page will be accessed.
+ */
+ if (is_kdump_kernel())
+ goto pgtable_walk;
+
/* get the pointer to pasid directory entry */
dir = phys_to_virt(ctx_entry->lo & VTD_PAGE_MASK);
if (!dir) {
--
1.8.3.1