[RFC PATCH 18/20] x86/sgx: Enable EPC cgroup controller in SGX core

Kristen Carlson Accardi
2022-09-22T17:14:02Z

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

Add the appropriate calls to (un)charge a cgroup during EPC page
allocation and free, and to isolate pages for reclaim based on the
provided cgroup.

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/epc_cgroup.c | 2 +-
arch/x86/kernel/cpu/sgx/main.c | 65 +++++++++++++++++++++++++---
arch/x86/kernel/cpu/sgx/sgx.h | 7 ++-
3 files changed, 65 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/epc_cgroup.c b/arch/x86/kernel/cpu/sgx/epc_cgroup.c
index 0a61bb8548ff..71da3b499950 100644
--- a/arch/x86/kernel/cpu/sgx/epc_cgroup.c
+++ b/arch/x86/kernel/cpu/sgx/epc_cgroup.c
@@ -396,7 +396,7 @@ static int sgx_epc_cgroup_reclaim_pages(unsigned long nr_pages,
nr_pages = max(nr_pages, SGX_EPC_RECLAIM_MIN_PAGES);
nr_pages = min(nr_pages, SGX_EPC_RECLAIM_MAX_PAGES);

- return sgx_reclaim_epc_pages(nr_pages, rc->ignore_age);
+ return sgx_reclaim_epc_pages(nr_pages, rc->ignore_age, rc->epc_cg);
}

static int sgx_epc_cgroup_reclaim_failed(struct sgx_epc_reclaim_control *rc)
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 082c08228840..29653a0d4670 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -17,6 +17,7 @@
#include "driver.h"
#include "encl.h"
#include "encls.h"
+#include "epc_cgroup.h"

#define SGX_MAX_NR_TO_RECLAIM 32

@@ -33,6 +34,10 @@ static DEFINE_XARRAY(sgx_epc_address_space);
static struct sgx_epc_lru sgx_global_lru;
static inline struct sgx_epc_lru *sgx_lru(struct sgx_epc_page *epc_page)
{
+#ifdef CONFIG_CGROUP_SGX_EPC
+ if (epc_page->epc_cg)
+ return &epc_page->epc_cg->lru;
+#endif
return &sgx_global_lru;
}

@@ -321,6 +326,7 @@ void sgx_isolate_epc_pages(struct sgx_epc_lru *lru, int *nr_to_scan,
* sgx_reclaim_epc_pages() - Reclaim EPC pages from the consumers
* @nr_to_scan: Number of EPC pages to scan for reclaim
* @ignore_age: Reclaim a page even if it is young
+ * @epc_cg: EPC cgroup from which to reclaim
*
* Take a fixed number of pages from the head of the active page pool and
* reclaim them to the enclave's private shmem files. Skip the pages, which have
@@ -336,7 +342,8 @@ void sgx_isolate_epc_pages(struct sgx_epc_lru *lru, int *nr_to_scan,
*
* Return: number of EPC pages reclaimed
*/
-int sgx_reclaim_epc_pages(int nr_to_scan, bool ignore_age)
+int sgx_reclaim_epc_pages(int nr_to_scan, bool ignore_age,
+ struct sgx_epc_cgroup *epc_cg)
{
struct sgx_backing backing[SGX_MAX_NR_TO_RECLAIM];
struct sgx_epc_page *epc_page, *tmp;
@@ -347,8 +354,17 @@ int sgx_reclaim_epc_pages(int nr_to_scan, bool ignore_age)
int i = 0;
int ret;

- sgx_isolate_epc_pages(&sgx_global_lru, &nr_to_scan, &iso);
+ /*
+ * If a specific cgroup is not being targetted, take from the global
+ * list first, even when cgroups are enabled. If there are
+ * pages on the global LRU then they should get reclaimed asap.
+ */
+ if (!IS_ENABLED(CONFIG_CGROUP_SGX_EPC) || !epc_cg)
+ sgx_isolate_epc_pages(&sgx_global_lru, &nr_to_scan, &iso);

+#ifdef CONFIG_CGROUP_SGX_EPC
+ sgx_epc_cgroup_isolate_pages(epc_cg, &nr_to_scan, &iso);
+#endif
if (list_empty(&iso))
goto out;

@@ -394,6 +410,12 @@ int sgx_reclaim_epc_pages(int nr_to_scan, bool ignore_age)
kref_put(&encl_page->encl->refcount, sgx_encl_release);
epc_page->flags &= ~SGX_EPC_PAGE_RECLAIM_FLAGS;

+#ifdef CONFIG_CGROUP_SGX_EPC
+ if (epc_page->epc_cg) {
+ sgx_epc_cgroup_uncharge(epc_page->epc_cg);
+ epc_page->epc_cg = NULL;
+ }
+#endif
sgx_free_epc_page(epc_page);
}
out:
@@ -403,7 +425,11 @@ int sgx_reclaim_epc_pages(int nr_to_scan, bool ignore_age)

static bool sgx_can_reclaim(void)
{
+#ifdef CONFIG_CGROUP_SGX_EPC
+ return !sgx_epc_cgroup_lru_empty(NULL);
+#else
return !list_empty(&sgx_global_lru.reclaimable);
+#endif
}

static bool sgx_should_reclaim(unsigned long watermark)
@@ -420,7 +446,7 @@ static bool sgx_should_reclaim(unsigned long watermark)
void sgx_reclaim_direct(void)
{
if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
- sgx_reclaim_epc_pages(SGX_NR_TO_SCAN, false);
+ sgx_reclaim_epc_pages(SGX_NR_TO_SCAN, false, NULL);
}

static int ksgxd(void *p)
@@ -446,7 +472,7 @@ static int ksgxd(void *p)
sgx_should_reclaim(SGX_NR_HIGH_PAGES));

if (sgx_should_reclaim(SGX_NR_HIGH_PAGES))
- sgx_reclaim_epc_pages(SGX_NR_TO_SCAN, false);
+ sgx_reclaim_epc_pages(SGX_NR_TO_SCAN, false, NULL);
}

return 0;
@@ -600,7 +626,13 @@ int sgx_drop_epc_page(struct sgx_epc_page *page)
struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
{
struct sgx_epc_page *page;
+#ifdef CONFIG_CGROUP_SGX_EPC
+ struct sgx_epc_cgroup *epc_cg;

+ epc_cg = sgx_epc_cgroup_try_charge(current->mm, reclaim);
+ if (IS_ERR(epc_cg))
+ return ERR_CAST(epc_cg);
+#endif
for ( ; ; ) {
page = __sgx_alloc_epc_page();
if (!IS_ERR(page)) {
@@ -608,8 +640,10 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
break;
}

- if (!sgx_can_reclaim())
- return ERR_PTR(-ENOMEM);
+ if (!sgx_can_reclaim()) {
+ page = ERR_PTR(-ENOMEM);
+ break;
+ }

if (!reclaim) {
page = ERR_PTR(-EBUSY);
@@ -621,9 +655,17 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
break;
}

- sgx_reclaim_epc_pages(SGX_NR_TO_SCAN, false);
+ sgx_reclaim_epc_pages(SGX_NR_TO_SCAN, false, NULL);
}

+#ifdef CONFIG_CGROUP_SGX_EPC
+ if (!IS_ERR(page)) {
+ WARN_ON(page->epc_cg);
+ page->epc_cg = epc_cg;
+ } else {
+ sgx_epc_cgroup_uncharge(epc_cg);
+ }
+#endif
if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
wake_up(&ksgxd_waitq);

@@ -654,6 +696,12 @@ void sgx_free_epc_page(struct sgx_epc_page *page)
page->flags = SGX_EPC_PAGE_IS_FREE;

spin_unlock(&node->lock);
+#ifdef CONFIG_CGROUP_SGX_EPC
+ if (page->epc_cg) {
+ sgx_epc_cgroup_uncharge(page->epc_cg);
+ page->epc_cg = NULL;
+ }
+#endif
atomic_long_inc(&sgx_nr_free_pages);
}

@@ -818,6 +866,9 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
section->pages[i].flags = 0;
section->pages[i].owner = NULL;
section->pages[i].poison = 0;
+#ifdef CONFIG_CGROUP_SGX_EPC
+ section->pages[i].epc_cg = NULL;
+#endif
list_add_tail(&section->pages[i].list, &sgx_dirty_page_list);
}

diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index a4c7ee0a4958..3ea96779dd28 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -39,6 +39,7 @@
SGX_EPC_PAGE_RECLAIM_IN_PROGRESS | \
SGX_EPC_PAGE_ENCLAVE | \
SGX_EPC_PAGE_VERSION_ARRAY)
+struct sgx_epc_cgroup;

struct sgx_epc_page {
unsigned int section;
@@ -46,6 +47,9 @@ struct sgx_epc_page {
u16 poison;
void *owner;
struct list_head list;
+#ifdef CONFIG_CGROUP_SGX_EPC
+ struct sgx_epc_cgroup *epc_cg;
+#endif
};

/*
@@ -113,7 +117,8 @@ void sgx_reclaim_direct(void);
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);
-int sgx_reclaim_epc_pages(int nr_to_scan, bool ignore_age);
+int sgx_reclaim_epc_pages(int nr_to_scan, bool ignore_age,
+ struct sgx_epc_cgroup *epc_cg);
void sgx_isolate_epc_pages(struct sgx_epc_lru *lru, int *nr_to_scan,
struct list_head *dst);
bool sgx_epc_oom(struct sgx_epc_lru *lru);
--
2.37.3