The list_head member of struct hyp_page is only needed when the page is
attached to a free-list, which by definition implies the page is free.
As such, nothing prevents us from using the page itself to store the
list_head, hence reducing the size of the vmemmap.
Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx>
---
arch/arm64/kvm/hyp/include/nvhe/memory.h | 1 -
arch/arm64/kvm/hyp/nvhe/page_alloc.c | 39 ++++++++++++++++++++----
2 files changed, 33 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h
index fd78bde939ee..7691ab495eb4 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/memory.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h
@@ -12,7 +12,6 @@ struct hyp_page {
unsigned int refcount;
unsigned int order;
struct hyp_pool *pool;
- struct list_head node;
};
extern u64 __hyp_vmemmap;
diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
index 2602577daa00..34f0eb026dd2 100644
--- a/arch/arm64/kvm/hyp/nvhe/page_alloc.c
+++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
@@ -62,6 +62,34 @@ static struct hyp_page *__find_buddy_avail(struct hyp_pool *pool,
}
+/*
+ * Pages that are available for allocation are tracked in free-lists, so we use
+ * the pages themselves to store the list nodes to avoid wasting space. As the
+ * allocator always returns zeroed pages (which are zeroed on the hyp_put_page()
+ * path to optimize allocation speed), we also need to clean-up the list node in
+ * each page when we take it out of the list.
+ */
+static inline void page_remove_from_list(struct hyp_page *p)
+{
+ struct list_head *node = hyp_page_to_virt(p);
+
+ __list_del_entry(node);
+ memset(node, 0, sizeof(*node));
+}
+
+static inline void page_add_to_list(struct hyp_page *p, struct list_head *head)
+{
+ struct list_head *node = hyp_page_to_virt(p);
+
+ INIT_LIST_HEAD(node);
+ list_add_tail(node, head);
+}
+
+static inline struct hyp_page *node_to_page(struct list_head *node)
+{
+ return hyp_virt_to_page(node);
+}
+
static void __hyp_attach_page(struct hyp_pool *pool,
struct hyp_page *p)
{
@@ -83,14 +111,14 @@ static void __hyp_attach_page(struct hyp_pool *pool,
break;
/* Take the buddy out of its list, and coallesce with @p */
- list_del_init(&buddy->node);
+ page_remove_from_list(buddy);
buddy->order = HYP_NO_ORDER;
p = min(p, buddy);
}
/* Mark the new head, and insert it */
p->order = order;
- list_add_tail(&p->node, &pool->free_area[order]);
+ page_add_to_list(p, &pool->free_area[order]);
}
static struct hyp_page *__hyp_extract_page(struct hyp_pool *pool,
@@ -99,7 +127,7 @@ static struct hyp_page *__hyp_extract_page(struct hyp_pool *pool,
{
struct hyp_page *buddy;
- list_del_init(&p->node);
+ page_remove_from_list(p);
while (p->order > order) {
/*
* The buddy of order n - 1 currently has HYP_NO_ORDER as it
@@ -110,7 +138,7 @@ static struct hyp_page *__hyp_extract_page(struct hyp_pool *pool,
p->order--;
buddy = __find_buddy_nocheck(pool, p, p->order);
buddy->order = p->order;
- list_add_tail(&buddy->node, &pool->free_area[buddy->order]);
+ page_add_to_list(buddy, &pool->free_area[buddy->order]);
}
return p;
@@ -182,7 +210,7 @@ void *hyp_alloc_pages(struct hyp_pool *pool, unsigned int order)
}
/* Extract it from the tree at the right order */
- p = list_first_entry(&pool->free_area[i], struct hyp_page, node);
+ p = node_to_page(pool->free_area[i].next);
p = __hyp_extract_page(pool, p, order);
hyp_set_page_refcounted(p);
@@ -210,7 +238,6 @@ int hyp_pool_init(struct hyp_pool *pool, u64 pfn, unsigned int nr_pages,
for (i = 0; i < nr_pages; i++) {
p[i].pool = pool;
p[i].order = 0;
- INIT_LIST_HEAD(&p[i].node);
hyp_set_page_refcounted(&p[i]);
}
--
2.32.0.rc1.229.g3e70b5a671-goog
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