[PATCH 2/4] iommu/vt-d: Duplicate iommu_resv_region objects per device list

[Eric Auger]

intel_iommu_get_resv_regions() aims to return the list of
reserved regions accessible by a given @device. However several
devices can access the same reserved memory region and when
building the list it is not safe to use a single iommu_resv_region
object, whose container is the RMRR. This iommu_resv_region must
be duplicated per device reserved region list.

Let's remove the struct iommu_resv_region from the RMRR unit
and allocate the iommu_resv_region directly in
intel_iommu_get_resv_regions().

Fixes: 0659b8dc45a6 ("iommu/vt-d: Implement reserved region get/put callbacks")
Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
---
 drivers/iommu/intel-iommu.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 2075abdb174d..e2134b13c9ae 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -322,7 +322,6 @@ struct dmar_rmrr_unit {
 	u64	end_address;		/* reserved end address */
 	struct dmar_dev_scope *devices;	/* target devices */
 	int	devices_cnt;		/* target device count */
-	struct iommu_resv_region *resv; /* reserved region handle */
 };
 
 struct dmar_atsr_unit {
@@ -4206,7 +4205,6 @@ static inline void init_iommu_pm_ops(void) {}
 int __init dmar_parse_one_rmrr(struct acpi_dmar_header *header, void *arg)
 {
 	struct acpi_dmar_reserved_memory *rmrr;
-	int prot = DMA_PTE_READ|DMA_PTE_WRITE;
 	struct dmar_rmrr_unit *rmrru;
 	size_t length;
 
@@ -4220,22 +4218,16 @@ int __init dmar_parse_one_rmrr(struct acpi_dmar_header *header, void *arg)
 	rmrru->end_address = rmrr->end_address;
 
 	length = rmrr->end_address - rmrr->base_address + 1;
-	rmrru->resv = iommu_alloc_resv_region(rmrr->base_address, length, prot,
-					      IOMMU_RESV_DIRECT, GFP_KERNEL);
-	if (!rmrru->resv)
-		goto free_rmrru;
 
 	rmrru->devices = dmar_alloc_dev_scope((void *)(rmrr + 1),
 				((void *)rmrr) + rmrr->header.length,
 				&rmrru->devices_cnt);
 	if (rmrru->devices_cnt && rmrru->devices == NULL)
-		goto free_all;
+		goto free_rmrru;
 
 	list_add(&rmrru->list, &dmar_rmrr_units);
 
 	return 0;
-free_all:
-	kfree(rmrru->resv);
 free_rmrru:
 	kfree(rmrru);
 out:
@@ -4453,7 +4445,6 @@ static void intel_iommu_free_dmars(void)
 	list_for_each_entry_safe(rmrru, rmrr_n, &dmar_rmrr_units, list) {
 		list_del(&rmrru->list);
 		dmar_free_dev_scope(&rmrru->devices, &rmrru->devices_cnt);
-		kfree(rmrru->resv);
 		kfree(rmrru);
 	}
 
@@ -5271,6 +5262,7 @@ static void intel_iommu_remove_device(struct device *dev)
 static void intel_iommu_get_resv_regions(struct device *device,
 					 struct list_head *head)
 {
+	int prot = DMA_PTE_READ|DMA_PTE_WRITE;
 	struct iommu_resv_region *reg;
 	struct dmar_rmrr_unit *rmrr;
 	struct device *i_dev;
@@ -5280,10 +5272,21 @@ static void intel_iommu_get_resv_regions(struct device *device,
 	for_each_rmrr_units(rmrr) {
 		for_each_active_dev_scope(rmrr->devices, rmrr->devices_cnt,
 					  i, i_dev) {
+			struct iommu_resv_region *resv;
+			size_t length;
+
 			if (i_dev != device)
 				continue;
 
-			list_add_tail(&rmrr->resv->list, head);
+			length = rmrr->end_address - rmrr->base_address + 1;
+			resv = iommu_alloc_resv_region(rmrr->base_address,
+						       length, prot,
+						       IOMMU_RESV_DIRECT,
+						       GFP_ATOMIC);
+			if (!resv)
+				break;
+
+			list_add_tail(&resv->list, head);
 		}
 	}
 	rcu_read_unlock();
@@ -5301,10 +5304,8 @@ static void intel_iommu_put_resv_regions(struct device *dev,
 {
 	struct iommu_resv_region *entry, *next;
 
-	list_for_each_entry_safe(entry, next, head, list) {
-		if (entry->type == IOMMU_RESV_MSI)
-			kfree(entry);
-	}
+	list_for_each_entry_safe(entry, next, head, list)
+		kfree(entry);
 }
 
 #ifdef CONFIG_INTEL_IOMMU_SVM
-- 
2.20.1