iommu/vt-d: Acquiring lock in domain ID allocation helpers

The iommu->lock is used to protect the per-IOMMU domain ID resource.
Moving the lock into the ID alloc/free helpers makes the code more
compact. At the same time, the device_domain_lock is irrelevant to
the domain ID resource, remove its assertion as well.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20220706025524.2904370-7-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: LuBaolu

drivers/iommu/intel/iommu.c

@@ -1779,16 +1779,13 @@ static struct dmar_domain *alloc_domain(unsigned int type)
 	return domain;
 }
 
-/* Must be called with iommu->lock */
 static int domain_attach_iommu(struct dmar_domain *domain,
 			       struct intel_iommu *iommu)
 {
 	unsigned long ndomains;
-	int num;
-
-	assert_spin_locked(&device_domain_lock);
-	assert_spin_locked(&iommu->lock);
+	int num, ret = 0;
 
+	spin_lock(&iommu->lock);
 	domain->iommu_refcnt[iommu->seq_id] += 1;
 	if (domain->iommu_refcnt[iommu->seq_id] == 1) {
 		ndomains = cap_ndoms(iommu->cap);
@@ -1797,7 +1794,8 @@ static int domain_attach_iommu(struct dmar_domain *domain,
 		if (num >= ndomains) {
 			pr_err("%s: No free domain ids\n", iommu->name);
 			domain->iommu_refcnt[iommu->seq_id] -= 1;
-			return -ENOSPC;
+			ret = -ENOSPC;
+			goto out_unlock;
 		}
 
 		set_bit(num, iommu->domain_ids);
@@ -1806,24 +1804,25 @@ static int domain_attach_iommu(struct dmar_domain *domain,
 		domain_update_iommu_cap(domain);
 	}
 
-	return 0;
+out_unlock:
+	spin_unlock(&iommu->lock);
+	return ret;
 }
 
 static void domain_detach_iommu(struct dmar_domain *domain,
 				struct intel_iommu *iommu)
 {
 	int num;
 
-	assert_spin_locked(&device_domain_lock);
-	assert_spin_locked(&iommu->lock);
-
+	spin_lock(&iommu->lock);
 	domain->iommu_refcnt[iommu->seq_id] -= 1;
 	if (domain->iommu_refcnt[iommu->seq_id] == 0) {
 		num = domain->iommu_did[iommu->seq_id];
 		clear_bit(num, iommu->domain_ids);
 		domain_update_iommu_cap(domain);
 		domain->iommu_did[iommu->seq_id] = 0;
 	}
+	spin_unlock(&iommu->lock);
 }
 
 static inline int guestwidth_to_adjustwidth(int gaw)
@@ -2472,9 +2471,7 @@ static int domain_add_dev_info(struct dmar_domain *domain, struct device *dev)
 
 	spin_lock(&device_domain_lock);
 	info->domain = domain;
-	spin_lock(&iommu->lock);
 	ret = domain_attach_iommu(domain, iommu);
-	spin_unlock(&iommu->lock);
 	if (ret) {
 		spin_unlock(&device_domain_lock);
 		return ret;
@@ -4178,10 +4175,7 @@ static void __dmar_remove_one_dev_info(struct device_domain_info *info)
 	}
 
 	list_del(&info->link);
-
-	spin_lock(&iommu->lock);
 	domain_detach_iommu(domain, iommu);
-	spin_unlock(&iommu->lock);
 }
 
 static void dmar_remove_one_dev_info(struct device *dev)