[RFC PATCH 07/20] x86/sgx: Use a list to track to-be-reclaimed pages during reclaim

Kristen Carlson Accardi
2022-09-22T17:16:15Z

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

Change sgx_reclaim_pages() to use a list rather than an array for
storing the epc_pages which will be reclaimed. This change is needed
to transition to the LRU implementation for EPC cgroup support.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Cc: Sean Christopherson <seanjc@google.com>
---
arch/x86/kernel/cpu/sgx/main.c | 43 +++++++++++++++-------------------
1 file changed, 19 insertions(+), 24 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 93aa9e09c26d..085c06fdc359 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -288,12 +288,11 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
*/
static void sgx_reclaim_pages(void)
{
- struct sgx_epc_page *chunk[SGX_NR_TO_SCAN];
struct sgx_backing backing[SGX_NR_TO_SCAN];
struct sgx_encl_page *encl_page;
- struct sgx_epc_page *epc_page;
+ struct sgx_epc_page *epc_page, *tmp;
pgoff_t page_index;
- int cnt = 0;
+ LIST_HEAD(iso);
int ret;
int i;

@@ -304,23 +303,26 @@ static void sgx_reclaim_pages(void)

epc_page = list_first_entry(&sgx_global_lru.reclaimable,
struct sgx_epc_page, list);
- list_del_init(&epc_page->list);
encl_page = epc_page->owner;

if (kref_get_unless_zero(&encl_page->encl->refcount) != 0) {
epc_page->flags |= SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
- chunk[cnt++] = epc_page;
+ list_move_tail(&epc_page->list, &iso);
} else {
- /* The owner is freeing the page. No need to add the
- * page back to the list of reclaimable pages.
+ /* The owner is freeing the page, remove it from the
+ * LRU list
*/
epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
+ list_del_init(&epc_page->list);
}
}
spin_unlock(&sgx_global_lru.lock);

- for (i = 0; i < cnt; i++) {
- epc_page = chunk[i];
+ if (list_empty(&iso))
+ goto out;
+
+ i = 0;
+ list_for_each_entry_safe(epc_page, tmp, &iso, list) {
encl_page = epc_page->owner;

if (!sgx_reclaimer_age(epc_page))
@@ -335,6 +337,7 @@ static void sgx_reclaim_pages(void)
goto skip;
}

+ i++;
encl_page->desc |= SGX_ENCL_PAGE_BEING_RECLAIMED;
mutex_unlock(&encl_page->encl->lock);
continue;
@@ -342,27 +345,19 @@ static void sgx_reclaim_pages(void)
skip:
spin_lock(&sgx_global_lru.lock);
epc_page->flags &= ~SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
- list_add_tail(&epc_page->list, &sgx_global_lru.reclaimable);
+ list_move_tail(&epc_page->list, &sgx_global_lru.reclaimable);
spin_unlock(&sgx_global_lru.lock);

kref_put(&encl_page->encl->refcount, sgx_encl_release);
-
- chunk[i] = NULL;
- }
-
- for (i = 0; i < cnt; i++) {
- epc_page = chunk[i];
- if (epc_page)
- sgx_reclaimer_block(epc_page);
}

- for (i = 0; i < cnt; i++) {
- epc_page = chunk[i];
- if (!epc_page)
- continue;
+ list_for_each_entry(epc_page, &iso, list)
+ sgx_reclaimer_block(epc_page);

+ i= 0;
+ list_for_each_entry_safe(epc_page, tmp, &iso, list) {
encl_page = epc_page->owner;
- sgx_reclaimer_write(epc_page, &backing[i]);
+ sgx_reclaimer_write(epc_page, &backing[i++]);

kref_put(&encl_page->encl->refcount, sgx_encl_release);
epc_page->flags &= ~(SGX_EPC_PAGE_RECLAIMER_TRACKED |
@@ -370,7 +365,7 @@ static void sgx_reclaim_pages(void)

sgx_free_epc_page(epc_page);
}
-
+out:
cond_resched();
}

--
2.37.3