[PATCH] Revert "iommu: Remove iova cpu hotplugging flushing"

[Janusz Krzysztofik]

This reverts commit 4123ac652bde17ebacd8d1c46295f1bced6f2b5b.
---
 drivers/iommu/iova.c       | 28 ++++++++++++++++++++++++++++
 include/linux/cpuhotplug.h |  1 +
 include/linux/iova.h       |  1 +
 3 files changed, 30 insertions(+)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index 7d246bce7d848..a44ad92fc5eb7 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -31,6 +31,16 @@ unsigned long iova_rcache_range(void)
 	return PAGE_SIZE << (IOVA_RANGE_CACHE_MAX_SIZE - 1);
 }
 
+static int iova_cpuhp_dead(unsigned int cpu, struct hlist_node *node)
+{
+	struct iova_domain *iovad;
+
+	iovad = hlist_entry_safe(node, struct iova_domain, cpuhp_dead);
+
+	free_cpu_cached_iovas(cpu, iovad);
+	return 0;
+}
+
 static void free_global_cached_iovas(struct iova_domain *iovad);
 
 static struct iova *to_iova(struct rb_node *node)
@@ -245,10 +255,21 @@ int iova_cache_get(void)
 {
 	mutex_lock(&iova_cache_mutex);
 	if (!iova_cache_users) {
+		int ret;
+
+		ret = cpuhp_setup_state_multi(CPUHP_IOMMU_IOVA_DEAD, "iommu/iova:dead", NULL,
+					iova_cpuhp_dead);
+		if (ret) {
+			mutex_unlock(&iova_cache_mutex);
+			pr_err("Couldn't register cpuhp handler\n");
+			return ret;
+		}
+
 		iova_cache = kmem_cache_create(
 			"iommu_iova", sizeof(struct iova), 0,
 			SLAB_HWCACHE_ALIGN, NULL);
 		if (!iova_cache) {
+			cpuhp_remove_multi_state(CPUHP_IOMMU_IOVA_DEAD);
 			mutex_unlock(&iova_cache_mutex);
 			pr_err("Couldn't create iova cache\n");
 			return -ENOMEM;
@@ -271,6 +292,7 @@ void iova_cache_put(void)
 	}
 	iova_cache_users--;
 	if (!iova_cache_users) {
+		cpuhp_remove_multi_state(CPUHP_IOMMU_IOVA_DEAD);
 		kmem_cache_destroy(iova_cache);
 	}
 	mutex_unlock(&iova_cache_mutex);
@@ -473,6 +495,8 @@ EXPORT_SYMBOL_GPL(free_iova_fast);
 
 static void iova_domain_free_rcaches(struct iova_domain *iovad)
 {
+	cpuhp_state_remove_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD,
+					    &iovad->cpuhp_dead);
 	free_iova_rcaches(iovad);
 }
 
@@ -724,6 +748,10 @@ int iova_domain_init_rcaches(struct iova_domain *iovad)
 		}
 	}
 
+	ret = cpuhp_state_add_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD,
+					       &iovad->cpuhp_dead);
+	if (ret)
+		goto out_err;
 	return 0;
 
 out_err:
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 8f541a6b63e41..f61447913db97 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -95,6 +95,7 @@ enum cpuhp_state {
 	CPUHP_PAGE_ALLOC,
 	CPUHP_NET_DEV_DEAD,
 	CPUHP_PCI_XGENE_DEAD,
+	CPUHP_IOMMU_IOVA_DEAD,
 	CPUHP_LUSTRE_CFS_DEAD,
 	CPUHP_AP_ARM_CACHE_B15_RAC_DEAD,
 	CPUHP_PADATA_DEAD,
diff --git a/include/linux/iova.h b/include/linux/iova.h
index 6fe3374e8dd65..83c00fac2acb1 100644
--- a/include/linux/iova.h
+++ b/include/linux/iova.h
@@ -37,6 +37,7 @@ struct iova_domain {
 	struct iova	anchor;		/* rbtree lookup anchor */
 
 	struct iova_rcache	*rcaches;
+	struct hlist_node	cpuhp_dead;
 };
 
 static inline unsigned long iova_size(struct iova *iova)
-- 
2.25.1