Commit 420d42f6 authored by Lu Baolu's avatar Lu Baolu Committed by Will Deacon
Browse files

iommu/vt-d: Fix lockdep splat in sva bind()/unbind() 



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

========================================================
WARNING: possible irq lock inversion dependency detected
5.11.0-rc1+ #828 Not tainted
--------------------------------------------------------
kworker/0:1H/120 just changed the state of lock:
ffffffffad9ea1b8 (device_domain_lock){..-.}-{2:2}, at:
iommu_flush_dev_iotlb.part.0+0x32/0x120
but this lock took another, SOFTIRQ-unsafe lock in the past:
 (&iommu->lock){+.+.}-{2:2}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this:
 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&iommu->lock);
                               local_irq_disable();
                               lock(device_domain_lock);
                               lock(&iommu->lock);
  <Interrupt>
    lock(device_domain_lock);

 *** DEADLOCK ***

Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20201231005323.2178523-5-baolu.lu@linux.intel.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 4df7b226

drivers/iommu/intel/svm.c

+8 −6
Original line number Diff line number Diff line
@@ -281,6 +281,7 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev, 
	struct dmar_domain *dmar_domain;

	struct device_domain_info *info;

	struct intel_svm *svm = NULL;

	unsigned long iflags;

	int ret = 0;



	if (WARN_ON(!iommu) || !data)
@@ -381,12 +382,12 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev, 
	 * each bind of a new device even with an existing PASID, we need to

	 * call the nested mode setup function here.

	 */

	spin_lock(&iommu->lock);

	spin_lock_irqsave(&iommu->lock, iflags);

	ret = intel_pasid_setup_nested(iommu, dev,

				       (pgd_t *)(uintptr_t)data->gpgd,

				       data->hpasid, &data->vendor.vtd, dmar_domain,

				       data->addr_width);

	spin_unlock(&iommu->lock);

	spin_unlock_irqrestore(&iommu->lock, iflags);

	if (ret) {

		dev_err_ratelimited(dev, "Failed to set up PASID %llu in nested mode, Err %d\n",

				    data->hpasid, ret);
@@ -486,6 +487,7 @@ intel_svm_bind_mm(struct device *dev, unsigned int flags, 
	struct device_domain_info *info;

	struct intel_svm_dev *sdev;

	struct intel_svm *svm = NULL;

	unsigned long iflags;

	int pasid_max;

	int ret;
@@ -605,14 +607,14 @@ intel_svm_bind_mm(struct device *dev, unsigned int flags, 
			}

		}



		spin_lock(&iommu->lock);

		spin_lock_irqsave(&iommu->lock, iflags);

		ret = intel_pasid_setup_first_level(iommu, dev,

				mm ? mm->pgd : init_mm.pgd,

				svm->pasid, FLPT_DEFAULT_DID,

				(mm ? 0 : PASID_FLAG_SUPERVISOR_MODE) |

				(cpu_feature_enabled(X86_FEATURE_LA57) ?

				 PASID_FLAG_FL5LP : 0));

		spin_unlock(&iommu->lock);

		spin_unlock_irqrestore(&iommu->lock, iflags);

		if (ret) {

			if (mm)

				mmu_notifier_unregister(&svm->notifier, mm);
@@ -632,14 +634,14 @@ intel_svm_bind_mm(struct device *dev, unsigned int flags, 
		 * Binding a new device with existing PASID, need to setup

		 * the PASID entry.

		 */

		spin_lock(&iommu->lock);

		spin_lock_irqsave(&iommu->lock, iflags);

		ret = intel_pasid_setup_first_level(iommu, dev,

						mm ? mm->pgd : init_mm.pgd,

						svm->pasid, FLPT_DEFAULT_DID,

						(mm ? 0 : PASID_FLAG_SUPERVISOR_MODE) |

						(cpu_feature_enabled(X86_FEATURE_LA57) ?

						PASID_FLAG_FL5LP : 0));

		spin_unlock(&iommu->lock);

		spin_unlock_irqrestore(&iommu->lock, iflags);

		if (ret) {

			kfree(sdev);

			goto out;