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

Haitao Huang
2023-09-23T03:07:37Z

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