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+ torvalds#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>

drivers/iommu/intel/iommu.c

@@ -2699,7 +2699,7 @@ 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);
@@ -2709,7 +2709,7 @@ 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);