[PATCH 16/25] iommu/vt-d: Check device list of domain in domain free path

[Lu Baolu <baolu.lu@linux.intel.com>]

When the IOMMU domain is about to be freed, it should not be set on any
device. Instead of silently dealing with some bug cases, it's better to
trigger a warning to report and fix any potential bugs at the first time.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20220706025524.2904370-9-baolu.lu@linux.intel.com
---
 drivers/iommu/intel/iommu.c | 18 +++---------------
 1 file changed, 3 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 3d53de8c7634..a94fb69e1f9a 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -294,7 +294,6 @@ static LIST_HEAD(dmar_satc_units);
 /* bitmap for indexing intel_iommus */
 static int g_num_of_iommus;
 
-static void domain_remove_dev_info(struct dmar_domain *domain);
 static void dmar_remove_one_dev_info(struct device *dev);
 static void __dmar_remove_one_dev_info(struct device_domain_info *info);
 
@@ -1841,10 +1840,6 @@ static inline int guestwidth_to_adjustwidth(int gaw)
 
 static void domain_exit(struct dmar_domain *domain)
 {
-
-	/* Remove associated devices and clear attached or cached domains */
-	domain_remove_dev_info(domain);
-
 	if (domain->pgd) {
 		LIST_HEAD(freelist);
 
@@ -1852,6 +1847,9 @@ static void domain_exit(struct dmar_domain *domain)
 		put_pages_list(&freelist);
 	}
 
+	if (WARN_ON(!list_empty(&domain->devices)))
+		return;
+
 	kfree(domain);
 }
 
@@ -2333,16 +2331,6 @@ static void domain_context_clear_one(struct device_domain_info *info, u8 bus, u8
 	__iommu_flush_dev_iotlb(info, 0, MAX_AGAW_PFN_WIDTH);
 }
 
-static void domain_remove_dev_info(struct dmar_domain *domain)
-{
-	struct device_domain_info *info, *tmp;
-
-	spin_lock(&device_domain_lock);
-	list_for_each_entry_safe(info, tmp, &domain->devices, link)
-		__dmar_remove_one_dev_info(info);
-	spin_unlock(&device_domain_lock);
-}
-
 static int domain_setup_first_level(struct intel_iommu *iommu,
 				    struct dmar_domain *domain,
 				    struct device *dev,
-- 
2.25.1