6.17-stable review patch. If anyone has any objections, please let me know.
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From: Vineeth Pillai (Google) vineeth@bitbyteword.org
[ Upstream commit fbe6070c73badca726e4ff7877320e6c62339917 ]
In legacy mode, SSPTPTR is ignored if TT is not 00b or 01b. SSPTPTR maybe uninitialized or zero in that case and may cause oops like:
Oops: general protection fault, probably for non-canonical address 0xf00087d3f000f000: 0000 [#1] SMP NOPTI CPU: 2 UID: 0 PID: 786 Comm: cat Not tainted 6.16.0 #191 PREEMPT(voluntary) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-5.fc42 04/01/2014 RIP: 0010:pgtable_walk_level+0x98/0x150 RSP: 0018:ffffc90000f279c0 EFLAGS: 00010206 RAX: 0000000040000000 RBX: ffffc90000f27ab0 RCX: 000000000000001e RDX: 0000000000000003 RSI: f00087d3f000f000 RDI: f00087d3f0010000 RBP: ffffc90000f27a00 R08: ffffc90000f27a98 R09: 0000000000000002 R10: 0000000000000000 R11: 0000000000000000 R12: f00087d3f000f000 R13: 0000000000000000 R14: 0000000040000000 R15: ffffc90000f27a98 FS: 0000764566dcb740(0000) GS:ffff8881f812c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000764566d44000 CR3: 0000000109d81003 CR4: 0000000000772ef0 PKRU: 55555554 Call Trace: <TASK> pgtable_walk_level+0x88/0x150 domain_translation_struct_show.isra.0+0x2d9/0x300 dev_domain_translation_struct_show+0x20/0x40 seq_read_iter+0x12d/0x490 ...
Avoid walking the page table if TT is not 00b or 01b.
Fixes: 2b437e804566 ("iommu/vt-d: debugfs: Support dumping a specified page table") Signed-off-by: Vineeth Pillai (Google) vineeth@bitbyteword.org Reviewed-by: Kevin Tian kevin.tian@intel.com Link: https://lore.kernel.org/r/20250814163153.634680-1-vineeth@bitbyteword.org Signed-off-by: Lu Baolu baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel joerg.roedel@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/intel/debugfs.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/intel/debugfs.c b/drivers/iommu/intel/debugfs.c index affbf4a1558de..5aa7f46a420b5 100644 --- a/drivers/iommu/intel/debugfs.c +++ b/drivers/iommu/intel/debugfs.c @@ -435,8 +435,21 @@ static int domain_translation_struct_show(struct seq_file *m, } pgd &= VTD_PAGE_MASK; } else { /* legacy mode */ - pgd = context->lo & VTD_PAGE_MASK; - agaw = context->hi & 7; + u8 tt = (u8)(context->lo & GENMASK_ULL(3, 2)) >> 2; + + /* + * According to Translation Type(TT), + * get the page table pointer(SSPTPTR). + */ + switch (tt) { + case CONTEXT_TT_MULTI_LEVEL: + case CONTEXT_TT_DEV_IOTLB: + pgd = context->lo & VTD_PAGE_MASK; + agaw = context->hi & 7; + break; + default: + goto iommu_unlock; + } }
seq_printf(m, "Device %04x:%02x:%02x.%x ",