[RFC PATCH 04/20] x86/sgx: Add 'struct sgx_epc_lru' to encapsulate lru list(s)

Kristen Carlson Accardi
2022-09-22T17:10:41Z

From: Sean Christopherson <sean.j.christopherson-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

Wrap the existing reclaimable list and its spinlock in a struct to
minimize the code changes needed to handle multiple LRUs as well as
reclaimable and non-reclaimable lists, both of which will be introduced
and used by SGX EPC cgroups.

Signed-off-by: Sean Christopherson <sean.j.christopherson-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Kristen Carlson Accardi <kristen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Cc: Sean Christopherson <seanjc-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
---
arch/x86/kernel/cpu/sgx/main.c | 37 +++++++++++++++++-----------------
arch/x86/kernel/cpu/sgx/sgx.h | 11 ++++++++++
2 files changed, 30 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 4cdeb915dc86..af68dc1c677b 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -26,10 +26,9 @@ static DEFINE_XARRAY(sgx_epc_address_space);

/*
* These variables are part of the state of the reclaimer, and must be accessed
- * with sgx_reclaimer_lock acquired.
+ * with sgx_global_lru.lock acquired.
*/
-static LIST_HEAD(sgx_active_page_list);
-static DEFINE_SPINLOCK(sgx_reclaimer_lock);
+static struct sgx_epc_lru sgx_global_lru;

static atomic_long_t sgx_nr_free_pages = ATOMIC_LONG_INIT(0);

@@ -298,12 +297,12 @@ static void sgx_reclaim_pages(void)
int ret;
int i;

- spin_lock(&sgx_reclaimer_lock);
+ spin_lock(&sgx_global_lru.lock);
for (i = 0; i < SGX_NR_TO_SCAN; i++) {
- if (list_empty(&sgx_active_page_list))
+ if (list_empty(&sgx_global_lru.reclaimable))
break;

- epc_page = list_first_entry(&sgx_active_page_list,
+ 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;
@@ -316,7 +315,7 @@ static void sgx_reclaim_pages(void)
*/
epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
}
- spin_unlock(&sgx_reclaimer_lock);
+ spin_unlock(&sgx_global_lru.lock);

for (i = 0; i < cnt; i++) {
epc_page = chunk[i];
@@ -339,9 +338,9 @@ static void sgx_reclaim_pages(void)
continue;

skip:
- spin_lock(&sgx_reclaimer_lock);
- list_add_tail(&epc_page->list, &sgx_active_page_list);
- spin_unlock(&sgx_reclaimer_lock);
+ spin_lock(&sgx_global_lru.lock);
+ list_add_tail(&epc_page->list, &sgx_global_lru.reclaimable);
+ spin_unlock(&sgx_global_lru.lock);

kref_put(&encl_page->encl->refcount, sgx_encl_release);

@@ -374,7 +373,7 @@ static void sgx_reclaim_pages(void)
static bool sgx_should_reclaim(unsigned long watermark)
{
return atomic_long_read(&sgx_nr_free_pages) < watermark &&
- !list_empty(&sgx_active_page_list);
+ !list_empty(&sgx_global_lru.reclaimable);
}

/*
@@ -427,6 +426,8 @@ static bool __init sgx_page_reclaimer_init(void)

ksgxd_tsk = tsk;

+ sgx_lru_init(&sgx_global_lru);
+
return true;
}

@@ -502,10 +503,10 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
*/
void sgx_mark_page_reclaimable(struct sgx_epc_page *page)
{
- spin_lock(&sgx_reclaimer_lock);
+ spin_lock(&sgx_global_lru.lock);
page->flags |= SGX_EPC_PAGE_RECLAIMER_TRACKED;
- list_add_tail(&page->list, &sgx_active_page_list);
- spin_unlock(&sgx_reclaimer_lock);
+ list_add_tail(&page->list, &sgx_global_lru.reclaimable);
+ spin_unlock(&sgx_global_lru.lock);
}

/**
@@ -520,18 +521,18 @@ void sgx_mark_page_reclaimable(struct sgx_epc_page *page)
*/
int sgx_unmark_page_reclaimable(struct sgx_epc_page *page)
{
- spin_lock(&sgx_reclaimer_lock);
+ spin_lock(&sgx_global_lru.lock);
if (page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED) {
/* The page is being reclaimed. */
if (list_empty(&page->list)) {
- spin_unlock(&sgx_reclaimer_lock);
+ spin_unlock(&sgx_global_lru.lock);
return -EBUSY;
}

list_del(&page->list);
page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
}
- spin_unlock(&sgx_reclaimer_lock);
+ spin_unlock(&sgx_global_lru.lock);

return 0;
}
@@ -564,7 +565,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
break;
}

- if (list_empty(&sgx_active_page_list))
+ if (list_empty(&sgx_global_lru.reclaimable))
return ERR_PTR(-ENOMEM);

if (!reclaim) {
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 5a7e858a8f98..7b208ee8eb45 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -83,6 +83,17 @@ static inline void *sgx_get_epc_virt_addr(struct sgx_epc_page *page)
return section->virt_addr + index * PAGE_SIZE;
}

+struct sgx_epc_lru {
+ spinlock_t lock;
+ struct list_head reclaimable;
+};
+
+static inline void sgx_lru_init(struct sgx_epc_lru *lru)
+{
+ spin_lock_init(&lru->lock);
+ INIT_LIST_HEAD(&lru->reclaimable);
+}
+
struct sgx_epc_page *__sgx_alloc_epc_page(void);
void sgx_free_epc_page(struct sgx_epc_page *page);

--
2.37.3