[PATCH 5/5] iommu/vt-d: Fix lockdep splat due to klist iteration in atomic context
Lucas De Marchi
lucas.demarchi at intel.com
Fri Aug 26 16:56:05 UTC 2022
From: Lu Baolu <baolu.lu at linux.intel.com>
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): [<ffffffff85000e86>] asm_sysvec_apic_timer_interrupt+0x16/0x20
hardirqs last disabled at (7812): [<ffffffff84f16894>] irqentry_enter+0x54/0x60
softirqs last enabled at (7794): [<ffffffff840ff669>] __irq_exit_rcu+0xf9/0x170
softirqs last disabled at (7787): [<ffffffff840ff669>] __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: 8ac0b64b9735 ("iommu/vt-d: Use pci_get_domain_bus_and_slot() in pgtable_walk()")
Reported-by: Lennert Buytenhek <buytenh at wantstofly.org>
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 <baolu.lu at linux.intel.com>
Link: https://lore.kernel.org/r/20220819015949.4795-1-baolu.lu@linux.intel.com
---
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 1ab63a8ef4c6..0684189a3dc5 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -811,32 +811,11 @@ 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);
@@ -863,9 +842,10 @@ 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);
@@ -893,8 +873,11 @@ 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);
@@ -921,8 +904,16 @@ 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
--
2.37.2
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