Enclave Page Cache(EPC) memory can be swapped out to regular system
memory, and the consumed memory should be charged to a proper
mem_cgroup. Currently the selection of mem_cgroup to charge is done in
sgx_encl_get_mem_cgroup(). But it considers all contexts other than the
ksgxd thread are user processes. With the new EPC cgroup implementation,
the swapping can also happen in EPC cgroup work-queue threads. In those
cases, it improperly selects the root mem_cgroup to charge for the RAM
usage.
Remove current_is_ksgxd() and change sgx_encl_get_mem_cgroup() to take
an additional argument to explicitly specify the mm struct to charge for
allocations. Callers from background kthreads not associated with a
charging mm struct would set it to NULL, while callers in user process
contexts set it to current->mm.
Internally, it handles the case when the charging mm given is NULL, by
searching for an mm struct from enclave's mm_list.
Signed-off-by: Haitao Huang
Reported-by: Mikko Ylinen
Tested-by: Mikko Ylinen
Tested-by: Jarkko Sakkinen
---
V10:
- Pass mm struct instead of a boolean 'indirect'. (Dave, Jarkko)
V9:
- Reduce number of if statements. (Tim)
V8:
- Limit text paragraphs to 80 characters wide. (Jarkko)
---
arch/x86/kernel/cpu/sgx/encl.c | 29 ++--
arch/x86/kernel/cpu/sgx/encl.h | 3 +--
arch/x86/kernel/cpu/sgx/epc_cgroup.c | 10 ++
arch/x86/kernel/cpu/sgx/main.c | 29 +---
arch/x86/kernel/cpu/sgx/sgx.h| 2 +-
5 files changed, 36 insertions(+), 37 deletions(-)
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index f474179b6f77..7b77dad41daf 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -993,23 +993,23 @@ static int __sgx_encl_get_backing(struct sgx_encl *encl,
unsigned long page_inde
}
/*
- * When called from ksgxd, returns the mem_cgroup of a struct mm stored
- * in the enclave's mm_list. When not called from ksgxd, just returns
- * the mem_cgroup of the current task.
+ * Find the mem_cgroup to charge for memory allocated on behalf of an enclave.
+ *
+ * Used in sgx_encl_alloc_backing() for backing store allocation.
+ *
+ * Return the mem_cgroup of the given charge_mm. Otherwise return the
mem_cgroup
+ * of a struct mm stored in the enclave's mm_list.
*/
-static struct mem_cgroup *sgx_encl_get_mem_cgroup(struct sgx_encl *encl)
+static struct mem_cgroup *sgx_encl_get_mem_cgroup(struct sgx_encl *encl,
+ struct mm_struct *charge_mm)
{
struct mem_cgroup *memcg = NULL;
struct sgx_encl_mm *encl_mm;
int idx;
- /*
-* If called from normal task context, return the mem_cgroup
-* of the current task's mm. The remainder of the handling is for
-* ksgxd.
-*/
- if (!current_is_ksgxd())
- return get_mem_cgroup_from_mm(current->mm);
+/* Use the charge_mm if given. */
+ if (charge_mm)
+ return get_mem_cgroup_from_mm(charge_mm);
/*
* Search the enclave's mm_list to find an mm associated with
@@ -1047,8 +1047,9 @@ static struct mem_cgroup *sgx_encl_get_mem_cgroup(struct
sgx_encl *encl)
* @encl: an enclave pointer
* @page_index:enclave page index
* @backing: data for accessing backing storage for the page
+ * @charge_mm: the mm to charge for the allocation
*
- * When called from ksgxd, sets the active memcg from one of the
+ * When charge_mm is NULL, sets the active memcg from one of the
* mms in the enclave's mm_list prior to any backing page allocation,
* in order to ensure that shmem page allocations are charged to the
* enclave. Create a backing page for loading data back into an EPC page with
@@ -1060,9 +1061,9 @@ static struct mem_cgroup *sgx_encl_get_mem_cgroup(struct
sgx_encl *encl)
* -errno otherwise.
*/
int sgx_encl_alloc_backing(struct sgx_encl *encl, unsigned long page_index,
- struct sgx_backing *backing)
+ struct sgx_backing *backing, struct mm_struct
*charge_mm)
{
- struct mem_cgroup *encl_memcg = sgx_encl_get_mem_cgroup(encl);
+ struct mem_cgroup *encl_memcg = sgx_encl_get_mem_cgroup(encl,
charge_mm);
struct mem_cgroup *memcg = set_active_memcg(encl_memcg);
int ret;
diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
index fe15ade02ca1..5ce9d108290f 100644
--- a/arch/x86/kernel/cpu/sgx/encl.h
+++ b/arch/x86/kernel/cpu/sgx/encl.h
@@ -103,12 +103,11 @@ static inline int sgx_encl_find(struct mm_struct *mm,
unsigned long addr,
int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start,
unsigned long end, unsigned long vm_flags);
-bool current_is_ksgxd(void);
void sgx_encl_release(struct kref *ref);
int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm);
const cpumask_t *sgx_encl_cpumask(struc
