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

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Date:   Tue, 12 Jul 2022 08:08:59 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     iommu@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH 16/25] iommu/vt-d: Check device list of domain in domain free path

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@...ux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
Reviewed-by: Kevin Tian <kevin.tian@...el.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