iommu/vt-d: Fix RCU-list bugs in intel_iommu_init()

There are several places traverse RCU-list without holding any lock in
intel_iommu_init(). Fix them by acquiring dmar_global_lock.

 WARNING: suspicious RCU usage
 -----------------------------
 drivers/iommu/intel-iommu.c:5216 RCU-list traversed in non-reader section!!

 other info that might help us debug this:

 rcu_scheduler_active = 2, debug_locks = 1
 no locks held by swapper/0/1.

 Call Trace:
  dump_stack+0xa0/0xea
  lockdep_rcu_suspicious+0x102/0x10b
  intel_iommu_init+0x947/0xb13
  pci_iommu_init+0x26/0x62
  do_one_initcall+0xfe/0x500
  kernel_init_freeable+0x45a/0x4f8
  kernel_init+0x11/0x139
  ret_from_fork+0x3a/0x50
 DMAR: Intel(R) Virtualization Technology for Directed I/O

Fixes: d8190dc63886 ("iommu/vt-d: Enable DMA remapping after rmrr mapped")
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 33593fea0250c0dd9f309de9ddacda65f9661d1f..693380355dead7bb25a3fd450824ba3719767b16 100644 (file)
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5193,6 +5193,7 @@ int __init intel_iommu_init(void)
 
        init_iommu_pm_ops();
 
+       down_read(&dmar_global_lock);
        for_each_active_iommu(iommu, drhd) {
                iommu_device_sysfs_add(&iommu->iommu, NULL,
                                       intel_iommu_groups,
@@ -5200,6 +5201,7 @@ int __init intel_iommu_init(void)
                iommu_device_set_ops(&iommu->iommu, &intel_iommu_ops);
                iommu_device_register(&iommu->iommu);
        }
+       up_read(&dmar_global_lock);
 
        bus_set_iommu(&pci_bus_type, &intel_iommu_ops);
        if (si_domain && !hw_pass_through)
@@ -5210,7 +5212,6 @@ int __init intel_iommu_init(void)
        down_read(&dmar_global_lock);
        if (probe_acpi_namespace_devices())
                pr_warn("ACPI name space devices didn't probe correctly\n");
-       up_read(&dmar_global_lock);
 
        /* Finally, we enable the DMA remapping hardware. */
        for_each_iommu(iommu, drhd) {
@@ -5219,6 +5220,8 @@ int __init intel_iommu_init(void)
 
                iommu_disable_protect_mem_regions(iommu);
        }
+       up_read(&dmar_global_lock);
+
        pr_info("Intel(R) Virtualization Technology for Directed I/O\n");
 
        intel_iommu_enabled = 1;