[PATCH v5 15/18] x86/sgx: Prepare for multiple LRUs

[Haitao Huang <haitao.huang@linux.intel.com>]

From: Sean Christopherson <sean.j.christopherson@intel.com>

Add wrappers where a direct references to the global LRU list in the
reclaimer functions.  To support  multiple LRU lists (one per EPC
cgroup) later, only make changes inside these wrappers.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Co-developed-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Co-developed-by: Haitao Huang <haitao.huang@linux.intel.com>
Signed-off-by: Haitao Huang <haitao.huang@linux.intel.com>
Cc: Sean Christopherson <seanjc@google.com>
---
V5:
- Revise commit message to make the purpose more clear.

V4:
- Re-organized this patch to include all changes related to
encapsulation of the global LRU
- Moved this patch to precede the EPC cgroup patch
---
 arch/x86/kernel/cpu/sgx/main.c | 41 +++++++++++++++++++++++-----------
 1 file changed, 28 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index b34ad3574c81..d37ef0dd865f 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -35,6 +35,16 @@ static DEFINE_XARRAY(sgx_epc_address_space);
  */
 static struct sgx_epc_lru_lists sgx_global_lru;
 
+static inline struct sgx_epc_lru_lists *sgx_lru_lists(struct sgx_epc_page *epc_page)
+{
+	return &sgx_global_lru;
+}
+
+static inline bool sgx_can_reclaim(void)
+{
+	return !list_empty(&sgx_global_lru.reclaimable);
+}
+
 static atomic_long_t sgx_nr_free_pages = ATOMIC_LONG_INIT(0);
 
 /* Nodes with one or more EPC sections. */
@@ -340,6 +350,7 @@ size_t sgx_reclaim_epc_pages(size_t nr_to_scan, bool ignore_age)
 	struct sgx_backing backing[SGX_NR_TO_SCAN_MAX];
 	struct sgx_epc_page *epc_page, *tmp;
 	struct sgx_encl_page *encl_page;
+	struct sgx_epc_lru_lists *lru;
 	pgoff_t page_index;
 	LIST_HEAD(iso);
 	size_t ret, i;
@@ -372,10 +383,11 @@ size_t sgx_reclaim_epc_pages(size_t nr_to_scan, bool ignore_age)
 		continue;
 
 skip:
-		spin_lock(&sgx_global_lru.lock);
+		lru = sgx_lru_lists(epc_page);
+		spin_lock(&lru->lock);
 		sgx_epc_page_set_state(epc_page, SGX_EPC_PAGE_RECLAIMABLE);
-		list_move_tail(&epc_page->list, &sgx_global_lru.reclaimable);
-		spin_unlock(&sgx_global_lru.lock);
+		list_move_tail(&epc_page->list, &lru->reclaimable);
+		spin_unlock(&lru->lock);
 
 		kref_put(&encl_page->encl->refcount, sgx_encl_release);
 	}
@@ -400,7 +412,7 @@ size_t sgx_reclaim_epc_pages(size_t nr_to_scan, bool ignore_age)
 static bool sgx_should_reclaim(unsigned long watermark)
 {
 	return atomic_long_read(&sgx_nr_free_pages) < watermark &&
-	       !list_empty(&sgx_global_lru.reclaimable);
+		sgx_can_reclaim();
 }
 
 /*
@@ -530,14 +542,16 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
  */
 void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
 {
-	spin_lock(&sgx_global_lru.lock);
+	struct sgx_epc_lru_lists *lru = sgx_lru_lists(page);
+
+	spin_lock(&lru->lock);
 	WARN_ON_ONCE(sgx_epc_page_reclaimable(page->flags));
 	page->flags |= flags;
 	if (sgx_epc_page_reclaimable(flags))
-		list_add_tail(&page->list, &sgx_global_lru.reclaimable);
+		list_add_tail(&page->list, &lru->reclaimable);
 	else
-		list_add_tail(&page->list, &sgx_global_lru.unreclaimable);
-	spin_unlock(&sgx_global_lru.lock);
+		list_add_tail(&page->list, &lru->unreclaimable);
+	spin_unlock(&lru->lock);
 }
 
 /**
@@ -552,15 +566,16 @@ void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
  */
 int sgx_drop_epc_page(struct sgx_epc_page *page)
 {
-	spin_lock(&sgx_global_lru.lock);
+	struct sgx_epc_lru_lists *lru = sgx_lru_lists(page);
+
+	spin_lock(&lru->lock);
 	if (sgx_epc_page_reclaim_in_progress(page->flags)) {
-		spin_unlock(&sgx_global_lru.lock);
+		spin_unlock(&lru->lock);
 		return -EBUSY;
 	}
-
 	list_del(&page->list);
 	sgx_epc_page_reset_state(page);
-	spin_unlock(&sgx_global_lru.lock);
+	spin_unlock(&lru->lock);
 
 	return 0;
 }
@@ -593,7 +608,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
 			break;
 		}
 
-		if (list_empty(&sgx_global_lru.reclaimable))
+		if (!sgx_can_reclaim())
 			return ERR_PTR(-ENOMEM);
 
 		if (!reclaim) {
-- 
2.25.1