From 1d70969c464869c4d5fcade7d0410471aa466877 Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Tue, 23 Aug 2022 14:15:57 +0800 Subject: [PATCH] iommu/vt-d: Fix lockdep splat due to klist iteration in atomic context With CONFIG_INTEL_IOMMU_DEBUGFS enabled, below lockdep splat are seen when an I/O fault occurs on a machine with an Intel IOMMU in it. DMAR: DRHD: handling fault status reg 3 DMAR: [DMA Write NO_PASID] Request device [00:1a.0] fault addr 0x0 [fault reason 0x05] PTE Write access is not set DMAR: Dump dmar0 table entries for IOVA 0x0 DMAR: root entry: 0x0000000127f42001 DMAR: context entry: hi 0x0000000000001502, low 0x000000012d8ab001 ================================ WARNING: inconsistent lock state 5.20.0-0.rc0.20220812git7ebfc85e2cd7.10.fc38.x86_64 #1 Not tainted -------------------------------- inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage. rngd/1006 [HC1[1]:SC0[0]:HE0:SE1] takes: ff177021416f2d78 (&k->k_lock){?.+.}-{2:2}, at: klist_next+0x1b/0x160 {HARDIRQ-ON-W} state was registered at: lock_acquire+0xce/0x2d0 _raw_spin_lock+0x33/0x80 klist_add_tail+0x46/0x80 bus_add_device+0xee/0x150 device_add+0x39d/0x9a0 add_memory_block+0x108/0x1d0 memory_dev_init+0xe1/0x117 driver_init+0x43/0x4d kernel_init_freeable+0x1c2/0x2cc kernel_init+0x16/0x140 ret_from_fork+0x1f/0x30 irq event stamp: 7812 hardirqs last enabled at (7811): [] asm_sysvec_apic_timer_interrupt+0x16/0x20 hardirqs last disabled at (7812): [] irqentry_enter+0x54/0x60 softirqs last enabled at (7794): [] __irq_exit_rcu+0xf9/0x170 softirqs last disabled at (7787): [] __irq_exit_rcu+0xf9/0x170 The klist iterator functions using spin_*lock_irq*() but the klist insertion functions using spin_*lock(), combined with the Intel DMAR IOMMU driver iterating over klists from atomic (hardirq) context, where pci_get_domain_bus_and_slot() calls into bus_find_device() which iterates over klists. As currently there's no plan to fix the klist to make it safe to use in atomic context, this fixes the lockdep splat by avoid calling pci_get_domain_bus_and_slot() in the hardirq context. Fixes: ad675e45e9fc ("iommu/vt-d: Use pci_get_domain_bus_and_slot() in pgtable_walk()") Reported-by: Lennert Buytenhek Link: https://lore.kernel.org/linux-iommu/Yvo2dfpEh%2FWC+Wrr@wantstofly.org/ Link: https://lore.kernel.org/linux-iommu/YvyBdPwrTuHHbn5X@wantstofly.org/ Signed-off-by: Lu Baolu Link: https://lore.kernel.org/r/20220819015949.4795-1-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/iommu/intel/iommu.c | 47 +++++++++++++++---------------------- 1 file changed, 19 insertions(+), 28 deletions(-) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index e3fe1a148187d..64d30895a4c8f 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -813,32 +813,11 @@ static void free_context_table(struct intel_iommu *iommu) } #ifdef CONFIG_DMAR_DEBUG -static void pgtable_walk(struct intel_iommu *iommu, unsigned long pfn, u8 bus, u8 devfn) +static void pgtable_walk(struct intel_iommu *iommu, unsigned long pfn, + u8 bus, u8 devfn, struct dma_pte *parent, int level) { - struct device_domain_info *info; - struct dma_pte *parent, *pte; - struct dmar_domain *domain; - struct pci_dev *pdev; - int offset, level; - - pdev = pci_get_domain_bus_and_slot(iommu->segment, bus, devfn); - if (!pdev) - return; - - info = dev_iommu_priv_get(&pdev->dev); - if (!info || !info->domain) { - pr_info("device [%02x:%02x.%d] not probed\n", - bus, PCI_SLOT(devfn), PCI_FUNC(devfn)); - return; - } - - domain = info->domain; - level = agaw_to_level(domain->agaw); - parent = domain->pgd; - if (!parent) { - pr_info("no page table setup\n"); - return; - } + struct dma_pte *pte; + int offset; while (1) { offset = pfn_level_offset(pfn, level); @@ -865,9 +844,10 @@ void dmar_fault_dump_ptes(struct intel_iommu *iommu, u16 source_id, struct pasid_entry *entries, *pte; struct context_entry *ctx_entry; struct root_entry *rt_entry; + int i, dir_index, index, level; u8 devfn = source_id & 0xff; u8 bus = source_id >> 8; - int i, dir_index, index; + struct dma_pte *pgtable; pr_info("Dump %s table entries for IOVA 0x%llx\n", iommu->name, addr); @@ -895,8 +875,11 @@ void dmar_fault_dump_ptes(struct intel_iommu *iommu, u16 source_id, ctx_entry->hi, ctx_entry->lo); /* legacy mode does not require PASID entries */ - if (!sm_supported(iommu)) + if (!sm_supported(iommu)) { + level = agaw_to_level(ctx_entry->hi & 7); + pgtable = phys_to_virt(ctx_entry->lo & VTD_PAGE_MASK); goto pgtable_walk; + } /* get the pointer to pasid directory entry */ dir = phys_to_virt(ctx_entry->lo & VTD_PAGE_MASK); @@ -923,8 +906,16 @@ void dmar_fault_dump_ptes(struct intel_iommu *iommu, u16 source_id, for (i = 0; i < ARRAY_SIZE(pte->val); i++) pr_info("pasid table entry[%d]: 0x%016llx\n", i, pte->val[i]); + if (pasid_pte_get_pgtt(pte) == PASID_ENTRY_PGTT_FL_ONLY) { + level = pte->val[2] & BIT_ULL(2) ? 5 : 4; + pgtable = phys_to_virt(pte->val[2] & VTD_PAGE_MASK); + } else { + level = agaw_to_level((pte->val[0] >> 2) & 0x7); + pgtable = phys_to_virt(pte->val[0] & VTD_PAGE_MASK); + } + pgtable_walk: - pgtable_walk(iommu, addr >> VTD_PAGE_SHIFT, bus, devfn); + pgtable_walk(iommu, addr >> VTD_PAGE_SHIFT, bus, devfn, pgtable, level); } #endif -- 2.39.5