On Mon, 08 Apr 2024 07:20:23 -0500, Huang, Kai <kai.huang@xxxxxxxxx> wrote:
--- a/arch/x86/kernel/cpu/sgx/epc_cgroup.h
+++ b/arch/x86/kernel/cpu/sgx/epc_cgroup.h
@@ -28,6 +28,10 @@ static inline int sgx_cgroup_try_charge(struct
sgx_cgroup *sgx_cg, enum sgx_recl
static inline void sgx_cgroup_uncharge(struct sgx_cgroup *sgx_cg) { }
static inline void sgx_cgroup_init(void) { }
+
+static inline void sgx_cgroup_reclaim_pages(struct misc_cg *root,
struct mm_struct *charge_mm)
+{
+}
#else
struct sgx_cgroup {
struct misc_cg *cg;
@@ -65,6 +69,9 @@ static inline void sgx_put_cg(struct sgx_cgroup
*sgx_cg)
int sgx_cgroup_try_charge(struct sgx_cgroup *sgx_cg, enum sgx_reclaim
reclaim);
void sgx_cgroup_uncharge(struct sgx_cgroup *sgx_cg);
+bool sgx_cgroup_lru_empty(struct misc_cg *root);
+bool sgx_cgroup_should_reclaim(struct sgx_cgroup *sgx_cg);
+void sgx_cgroup_reclaim_pages(struct misc_cg *root, struct mm_struct
*charge_mm);
Seems the decision to choose whether to implement a stub function for
some
function is quite random to me.
My impression is people in general don't like #ifdef in the C file but
prefer to
implementing it in the header in some helper function.
I guess you might want to just implement a stub function for each of the
3
functions exposed, so that we can eliminate some #ifdefs in the
sgx/main.c (see
below).
void sgx_cgroup_init(void);
#endif
diff --git a/arch/x86/kernel/cpu/sgx/main.c
b/arch/x86/kernel/cpu/sgx/main.c
index 7f92455d957d..68f28ff2d5ef 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -34,6 +34,16 @@ static struct sgx_epc_lru_list sgx_global_lru;
static inline struct sgx_epc_lru_list *sgx_lru_list(struct
sgx_epc_page *epc_page)
{
+#ifdef CONFIG_CGROUP_SGX_EPC
+ if (epc_page->sgx_cg)
+ return &epc_page->sgx_cg->lru;
+
+ /*
+ * This should not happen when cgroup is enabled: Every page belongs
+ * to a cgroup, or the root by default.
+ */
+ WARN_ON_ONCE(1);
In the case MISC cgroup is enabled in Kconfig but disabled by command
line, I
think this becomes legal now?
I'm not sure actually. Never saw the warning even if I set
"cgroup_disable=misc" in commandlibe. Tried both v1 and v2. Anyway, I
think we can remove this warning and we handle the NULL sgx_cg now.
+#endif
return &sgx_global_lru;
}
@@ -42,7 +52,11 @@ static inline struct sgx_epc_lru_list
*sgx_lru_list(struct sgx_epc_page *epc_pag
*/
static inline bool sgx_can_reclaim(void)
{
+#ifdef CONFIG_CGROUP_SGX_EPC
+ return !sgx_cgroup_lru_empty(misc_cg_root());
+#else
return !list_empty(&sgx_global_lru.reclaimable);
+#endif
}
Here you are using #ifdef CONFIG_CGRUP_SGX_EPC, but ...
static atomic_long_t sgx_nr_free_pages = ATOMIC_LONG_INIT(0);
@@ -404,7 +418,10 @@ static bool sgx_should_reclaim(unsigned long
watermark)
static void sgx_reclaim_pages_global(struct mm_struct *charge_mm)
{
- sgx_reclaim_pages(&sgx_global_lru, charge_mm);
+ if (IS_ENABLED(CONFIG_CGROUP_SGX_EPC))
+ sgx_cgroup_reclaim_pages(misc_cg_root(), charge_mm);
+ else
+ sgx_reclaim_pages(&sgx_global_lru, charge_mm);
}
... here you are using IS_ENABLED(CONFIG_CGROUP_SGX_EPC).
Any reason they are not consistent?
I was hesitant to expose sgx_global_lru needed for implementing
sgx_cgroup_lru_empty() stub which would also be a random decision and
overkill to just remove couple of #ifdefs in short functions.
Also, in the case where MISC cgroup is disabled via commandline, I think
it
won't work, because misc_cg_root() should be NULL in this case while
IS_ENABLED(CONFIG_CGROUP_SGX_EPC) is true.
The misc root cgroup is a static similar to sgx_cg_root. So
misc_cg_root() won't be NULL
However, based on how css_misc() was check NULL, I suppose
sgx_get_current_cg() may be NULL when cgroup is disabled (again not 100%
sure but we handle it anyway)
/*
@@ -414,6 +431,16 @@ static void sgx_reclaim_pages_global(struct
mm_struct *charge_mm)
*/
void sgx_reclaim_direct(void)
{
+#ifdef CONFIG_CGROUP_SGX_EPC
+ struct sgx_cgroup *sgx_cg = sgx_get_current_cg();
+
+ /* Make sure there are some free pages at cgroup level */
+ if (sgx_cg && sgx_cgroup_should_reclaim(sgx_cg)) {
+ sgx_cgroup_reclaim_pages(sgx_cg->cg, current->mm);
+ sgx_put_cg(sgx_cg);
+ }
+#endif
This #ifdef CONFIG_CGROUP_SGX_EPC can be removed if we implement a stub
function
for sgx_cgroup_should_reclaim().
Yes.
+ /* Make sure there are some free pages at global level */
if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
sgx_reclaim_pages_global(current->mm);
}
Thanks
Haitao
