iommu/vt-d: Fix lockdep splat in iommu_flush_dev_iotlb()

Lock(&iommu->lock) without disabling irq causes lockdep warnings.

[   12.703950] ========================================================
[   12.703962] WARNING: possible irq lock inversion dependency detected
[   12.703975] 5.9.0-rc6+ #659 Not tainted
[   12.703983] --------------------------------------------------------
[   12.703995] systemd-udevd/284 just changed the state of lock:
[   12.704007] ffffffffbd6ff4d8 (device_domain_lock){..-.}-{2:2}, at:
               iommu_flush_dev_iotlb.part.57+0x2e/0x90
[   12.704031] but this lock took another, SOFTIRQ-unsafe lock in the past:
[   12.704043]  (&iommu->lock){+.+.}-{2:2}
[   12.704045]

               and interrupts could create inverse lock ordering between
               them.

[   12.704073]
               other info that might help us debug this:
[   12.704085]  Possible interrupt unsafe locking scenario:

[   12.704097]        CPU0                    CPU1
[   12.704106]        ----                    ----
[   12.704115]   lock(&iommu->lock);
[   12.704123]                                local_irq_disable();
[   12.704134]                                lock(device_domain_lock);
[   12.704146]                                lock(&iommu->lock);
[   12.704158]   <Interrupt>
[   12.704164]     lock(device_domain_lock);
[   12.704174]
                *** DEADLOCK ***

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20200927062428.13713-1-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 87b17bac04c27c24622b825a4e1431817bc7cb16..2239c211178b667e01f6a653bc52c7347f5d818b 100644 (file)
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2664,7 +2664,7 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
                }
 
                /* Setup the PASID entry for requests without PASID: */
-               spin_lock(&iommu->lock);
+               spin_lock_irqsave(&iommu->lock, flags);
                if (hw_pass_through && domain_type_is_si(domain))
                        ret = intel_pasid_setup_pass_through(iommu, domain,
                                        dev, PASID_RID2PASID);
@@ -2674,7 +2674,7 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
                else
                        ret = intel_pasid_setup_second_level(iommu, domain,
                                        dev, PASID_RID2PASID);
-               spin_unlock(&iommu->lock);
+               spin_unlock_irqrestore(&iommu->lock, flags);
                if (ret) {
                        dev_err(dev, "Setup RID2PASID failed\n");
                        dmar_remove_one_dev_info(dev);