[PATCH v2 1/4] iova: Add CPU hotplug handler to flush rcaches

From: John Garry
Date: Thu Mar 25 2021 - 08:35:57 EST


Like the Intel IOMMU driver already does, flush the per-IOVA domain
CPU rcache when a CPU goes offline - there's no point in keeping it.

Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
---
drivers/iommu/iova.c | 30 +++++++++++++++++++++++++++++-
include/linux/cpuhotplug.h | 1 +
include/linux/iova.h | 1 +
3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index e6e2fa85271c..c78312560425 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -25,6 +25,17 @@ static void init_iova_rcaches(struct iova_domain *iovad);
static void free_iova_rcaches(struct iova_domain *iovad);
static void fq_destroy_all_entries(struct iova_domain *iovad);
static void fq_flush_timeout(struct timer_list *t);
+
+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);

void
@@ -51,6 +62,7 @@ init_iova_domain(struct iova_domain *iovad, unsigned long granule,
iovad->anchor.pfn_lo = iovad->anchor.pfn_hi = IOVA_ANCHOR;
rb_link_node(&iovad->anchor.node, NULL, &iovad->rbroot.rb_node);
rb_insert_color(&iovad->anchor.node, &iovad->rbroot);
+ cpuhp_state_add_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD, &iovad->cpuhp_dead);
init_iova_rcaches(iovad);
}
EXPORT_SYMBOL_GPL(init_iova_domain);
@@ -257,10 +269,21 @@ 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;
@@ -282,8 +305,10 @@ void iova_cache_put(void)
return;
}
iova_cache_users--;
- if (!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);
}
EXPORT_SYMBOL_GPL(iova_cache_put);
@@ -606,6 +631,9 @@ void put_iova_domain(struct iova_domain *iovad)
{
struct iova *iova, *tmp;

+ cpuhp_state_remove_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD,
+ &iovad->cpuhp_dead);
+
free_iova_flush_queue(iovad);
free_iova_rcaches(iovad);
rbtree_postorder_for_each_entry_safe(iova, tmp, &iovad->rbroot, node)
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index f14adb882338..cedac9986557 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -58,6 +58,7 @@ enum cpuhp_state {
CPUHP_NET_DEV_DEAD,
CPUHP_PCI_XGENE_DEAD,
CPUHP_IOMMU_INTEL_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 c834c01c0a5b..4be6c0ab4997 100644
--- a/include/linux/iova.h
+++ b/include/linux/iova.h
@@ -95,6 +95,7 @@ struct iova_domain {
flush-queues */
atomic_t fq_timer_on; /* 1 when timer is active, 0
when not */
+ struct hlist_node cpuhp_dead;
};

static inline unsigned long iova_size(struct iova *iova)
--
2.26.2