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Subject[PATCH AUTOSEL 5.4 50/73] iommu/vt-d: Fix RCU-list bugs in intel_iommu_init()
Date
From: Qian Cai <cai@lca.pw>

[ Upstream commit 2d48ea0efb8887ebba3e3720bb5b738aced4e574 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/iommu/intel-iommu.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 760a242d0801d..9b3d169c6ff53 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5023,6 +5023,7 @@ 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,
@@ -5030,6 +5031,7 @@ 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)
@@ -5040,7 +5042,6 @@ 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) {
@@ -5049,6 +5050,8 @@ 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;
--
2.20.1
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