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.d...@linux.alibaba.com> --- 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 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu