[PATCH 03/26] x86/sgx: Add 'struct sgx_epc_lru' to encapsulate lru list(s)

[Kristen Carlson Accardi]

Introduce a data structure to wrap the existing reclaimable list
and its spinlock in a struct to minimize the code changes needed
to handle multiple LRUs as well as reclaimable and non-reclaimable
lists, both of which will be introduced and used by SGX EPC cgroups.

Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Kristen Carlson Accardi <kristen@xxxxxxxxxxxxxxx>
Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 arch/x86/kernel/cpu/sgx/sgx.h | 45 +++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index efb10eacd3aa..aac7d4feb0fa 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -91,6 +91,51 @@ static inline void *sgx_get_epc_virt_addr(struct sgx_epc_page *page)
 	return section->virt_addr + index * PAGE_SIZE;
 }
 
+struct sgx_epc_lru {
+	spinlock_t lock;
+	struct list_head reclaimable;
+	struct list_head unreclaimable;
+};
+
+static inline void sgx_lru_init(struct sgx_epc_lru *lru)
+{
+	spin_lock_init(&lru->lock);
+	INIT_LIST_HEAD(&lru->reclaimable);
+	INIT_LIST_HEAD(&lru->unreclaimable);
+}
+
+/*
+ * Must be called with queue lock acquired
+ */
+static inline void __sgx_epc_page_list_push(struct list_head *list, struct sgx_epc_page *page)
+{
+	list_add_tail(&page->list, list);
+}
+
+/*
+ * Must be called with queue lock acquired
+ */
+static inline struct sgx_epc_page * __sgx_epc_page_list_pop(struct list_head *list)
+{
+	struct sgx_epc_page *epc_page;
+
+	if (list_empty(list))
+		return NULL;
+
+	epc_page = list_first_entry(list, struct sgx_epc_page, list);
+	list_del_init(&epc_page->list);
+	return epc_page;
+}
+
+#define sgx_epc_pop_reclaimable(lru) \
+	__sgx_epc_page_list_pop(&(lru)->reclaimable)
+#define sgx_epc_push_reclaimable(lru, page) \
+	__sgx_epc_page_list_push(&(lru)->reclaimable, page)
+#define sgx_epc_pop_unreclaimable(lru) \
+	__sgx_epc_page_list_pop(&(lru)->unreclaimable)
+#define sgx_epc_push_unreclaimable(lru, page) \
+	__sgx_epc_page_list_push(&(lru)->unreclaimable, page)
+
 struct sgx_epc_page *__sgx_alloc_epc_page(void);
 void sgx_free_epc_page(struct sgx_epc_page *page);
 
-- 
2.37.3