[PATCH v15 09/14] x86/sgx: Abstract check for global reclaimable pages

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

From: Kristen Carlson Accardi <kristen@linux.intel.com>

For the global reclaimer to determine if any page available for
reclamation at the global level, it currently only checks for emptiness
of the global LRU. That will be inadequate when pages are tracked in
multiple LRUs, one per cgroup. For this purpose, create a new helper,
sgx_can_reclaim_global(), to abstract this check. Currently it only
checks the global LRU, later will check emptiness of LRUs of all cgroups
when per-cgroup tracking is turned on.

Replace all the checks for emptiness of the global LRU,
list_empty(&sgx_global_lru.reclaimable), with calls to
sgx_can_reclaim_global().

Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@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>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
---
V13:
- Rename sgx_can_reclaim() to sgx_can_reclaim_global() and
sgx_should_reclaim() to sgx_should_reclaim_global(). (Kai)

V10:
- Add comments for the new function. (Jarkko)

V7:
- Split this out from the big patch, #10 in V6. (Dave, Kai)
---
 arch/x86/kernel/cpu/sgx/main.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index d272488c53bf..2c0a36be7cdd 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -37,6 +37,14 @@ static inline struct sgx_epc_lru_list *sgx_epc_page_lru(struct sgx_epc_page *epc
 	return &sgx_global_lru;
 }
 
+/*
+ * Check if there is any reclaimable page at global level.
+ */
+static inline bool sgx_can_reclaim_global(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. */
@@ -390,7 +398,7 @@ unsigned int sgx_reclaim_pages(struct sgx_epc_lru_list *lru)
 static bool sgx_should_reclaim_global(unsigned long watermark)
 {
 	return atomic_long_read(&sgx_nr_free_pages) < watermark &&
-	       !list_empty(&sgx_global_lru.reclaimable);
+		sgx_can_reclaim_global();
 }
 
 static void sgx_reclaim_pages_global(void)
@@ -596,7 +604,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, enum sgx_reclaim reclaim)
 			break;
 		}
 
-		if (list_empty(&sgx_global_lru.reclaimable)) {
+		if (!sgx_can_reclaim_global()) {
 			page = ERR_PTR(-ENOMEM);
 			break;
 		}
-- 
2.43.0