[PATCH v3 15/28] x86/sgx: Add helper to grab pages from an arbitrary EPC LRU

Haitao Huang
2023-07-12T23:03:19Z

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

Move the isolation loop into a helper, sgx_isolate_pages(), in
preparation for existence of multiple LRUs. Expose the helper to other
SGX code so that it can be called from the EPC cgroup code, e.g. to
isolate pages from a single cgroup LRU. Exposing the isolation loop
allows the cgroup iteration logic to be wholly encapsulated within the
cgroup code.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Haitao Huang <haitao.huang@linux.intel.com>
Cc: Sean Christopherson <seanjc@google.com>
---
arch/x86/kernel/cpu/sgx/main.c | 60 +++++++++++++++++++++-------------
arch/x86/kernel/cpu/sgx/sgx.h | 2 ++
2 files changed, 40 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index e9c9e0d97300..883470062514 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -288,6 +288,43 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
mutex_unlock(&encl->lock);
}

+/**
+ * sgx_isolate_epc_pages() - Isolate pages from an LRU for reclaim
+ * @lru: LRU from which to reclaim
+ * @nr_to_scan: Number of pages to scan for reclaim
+ * @dst: Destination list to hold the isolated pages
+ */
+void sgx_isolate_epc_pages(struct sgx_epc_lru_lists *lru, size_t nr_to_scan,
+ struct list_head *dst)
+{
+ struct sgx_encl_page *encl_page;
+ struct sgx_epc_page *epc_page;
+
+ spin_lock(&lru->lock);
+ for (; nr_to_scan > 0; --nr_to_scan) {
+ epc_page = list_first_entry_or_null(&lru->reclaimable, struct sgx_epc_page, list);
+ if (!epc_page)
+ break;
+
+ encl_page = epc_page->encl_page;
+
+ if (WARN_ON_ONCE(!(epc_page->flags & SGX_EPC_OWNER_ENCL_PAGE)))
+ continue;
+
+ if (kref_get_unless_zero(&encl_page->encl->refcount)) {
+ sgx_epc_page_set_state(epc_page, SGX_EPC_PAGE_RECLAIM_IN_PROGRESS);
+ list_move_tail(&epc_page->list, dst);
+ } else {
+ /* The owner is freeing the page, remove it from the
+ * LRU list
+ */
+ sgx_epc_page_reset_state(epc_page);
+ list_del_init(&epc_page->list);
+ }
+ }
+ spin_unlock(&lru->lock);
+}
+
/**
* sgx_reclaim_epc_pages() - Reclaim EPC pages from the consumers
* @nr_to_scan: Number of EPC pages to scan for reclaim
@@ -316,28 +353,7 @@ size_t sgx_reclaim_epc_pages(size_t nr_to_scan, bool ignore_age)
size_t ret;
size_t i;

- spin_lock(&sgx_global_lru.lock);
- for (i = 0; i < SGX_NR_TO_SCAN; i++) {
- epc_page = list_first_entry_or_null(&sgx_global_lru.reclaimable,
- struct sgx_epc_page, list);
- if (!epc_page)
- break;
-
- list_del_init(&epc_page->list);
- encl_page = epc_page->encl_page;
-
- if (kref_get_unless_zero(&encl_page->encl->refcount) != 0) {
- sgx_epc_page_set_state(epc_page, SGX_EPC_PAGE_RECLAIM_IN_PROGRESS);
- list_move_tail(&epc_page->list, &iso);
- } else {
- /* The owner is freeing the page, remove it from the
- * LRU list
- */
- sgx_epc_page_reset_state(epc_page);
- list_del_init(&epc_page->list);
- }
- }
- spin_unlock(&sgx_global_lru.lock);
+ sgx_isolate_epc_pages(&sgx_global_lru, nr_to_scan, &iso);

if (list_empty(&iso))
return 0;
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 98d3b15341b1..25db815f5add 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -176,6 +176,8 @@ void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags);
int sgx_drop_epc_page(struct sgx_epc_page *page);
struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim);
size_t sgx_reclaim_epc_pages(size_t nr_to_scan, bool ignore_age);
+void sgx_isolate_epc_pages(struct sgx_epc_lru_lists *lrus, size_t nr_to_scan,
+ struct list_head *dst);

void sgx_ipi_cb(void *info);

--
2.25.1