iommu/vt-d: Unnecessary spinlock for root table alloc and free

The IOMMU root table is allocated and freed in the IOMMU initialization code in static boot or hot-remove paths. There's no need for a spinlock. Signed-off-by: Lu Baolu <[email protected]> Reviewed-by: Kevin Tian <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Joerg Roedel <[email protected]>
kinvolk · Jul 15, 2022 · 2e1c8da · 2e1c8da
1 parent 8ac0b64
commit 2e1c8da
Showing 1 changed file with 5 additions and 13 deletions.
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
@@ -809,14 +809,12 @@ static int device_context_mapped(struct intel_iommu *iommu, u8 bus, u8 devfn)
 
 static void free_context_table(struct intel_iommu *iommu)
 {
-	int i;
-	unsigned long flags;
 	struct context_entry *context;
+	int i;
+
+	if (!iommu->root_entry)
+		return;
 
-	spin_lock_irqsave(&iommu->lock, flags);
-	if (!iommu->root_entry) {
-		goto out;
-	}
 	for (i = 0; i < ROOT_ENTRY_NR; i++) {
 		context = iommu_context_addr(iommu, i, 0, 0);
 		if (context)
@@ -828,12 +826,10 @@ static void free_context_table(struct intel_iommu *iommu)
 		context = iommu_context_addr(iommu, i, 0x80, 0);
 		if (context)
 			free_pgtable_page(context);
-
 	}
+
 	free_pgtable_page(iommu->root_entry);
 	iommu->root_entry = NULL;
-out:
-	spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
 #ifdef CONFIG_DMAR_DEBUG
@@ -1232,7 +1228,6 @@ static void domain_unmap(struct dmar_domain *domain, unsigned long start_pfn,
 static int iommu_alloc_root_entry(struct intel_iommu *iommu)
 {
 	struct root_entry *root;
-	unsigned long flags;
 
 	root = (struct root_entry *)alloc_pgtable_page(iommu->node);
 	if (!root) {
@@ -1242,10 +1237,7 @@ static int iommu_alloc_root_entry(struct intel_iommu *iommu)
 	}
 
 	__iommu_flush_cache(iommu, root, ROOT_SIZE);
-
-	spin_lock_irqsave(&iommu->lock, flags);
 	iommu->root_entry = root;
-	spin_unlock_irqrestore(&iommu->lock, flags);
 
 	return 0;
 }