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Message-ID: <165442138274.152751.10575033225299242453.tglx@xen13>
Date: Sun, 5 Jun 2022 11:31:04 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org
Subject: [GIT pull] x86/urgent for v5.19-rc1
Linus,
please pull the latest x86/urgent branch from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-2022-06-05
up to: 0c9782e204d3: x86/sgx: Set active memcg prior to shmem allocation
A single fix for x86/SGX to prevent that memory which is allocated for an
SGX enclave is accounted to the wrong memory control group.
Thanks,
tglx
------------------>
Kristen Carlson Accardi (1):
x86/sgx: Set active memcg prior to shmem allocation
arch/x86/kernel/cpu/sgx/encl.c | 105 ++++++++++++++++++++++++++++++++++++++++-
arch/x86/kernel/cpu/sgx/encl.h | 7 ++-
arch/x86/kernel/cpu/sgx/main.c | 9 +++-
3 files changed, 115 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 3c24e6124d95..19876ebfb504 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -152,7 +152,7 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page,
page_pcmd_off = sgx_encl_get_backing_page_pcmd_offset(encl, page_index);
- ret = sgx_encl_get_backing(encl, page_index, &b);
+ ret = sgx_encl_lookup_backing(encl, page_index, &b);
if (ret)
return ret;
@@ -718,7 +718,7 @@ static struct page *sgx_encl_get_backing_page(struct sgx_encl *encl,
* 0 on success,
* -errno otherwise.
*/
-int sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index,
+static int sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index,
struct sgx_backing *backing)
{
pgoff_t page_pcmd_off = sgx_encl_get_backing_page_pcmd_offset(encl, page_index);
@@ -743,6 +743,107 @@ int sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index,
return 0;
}
+/*
+ * 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.
+ */
+static struct mem_cgroup *sgx_encl_get_mem_cgroup(struct sgx_encl *encl)
+{
+ 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);
+
+ /*
+ * Search the enclave's mm_list to find an mm associated with
+ * this enclave to charge the allocation to.
+ */
+ idx = srcu_read_lock(&encl->srcu);
+
+ list_for_each_entry_rcu(encl_mm, &encl->mm_list, list) {
+ if (!mmget_not_zero(encl_mm->mm))
+ continue;
+
+ memcg = get_mem_cgroup_from_mm(encl_mm->mm);
+
+ mmput_async(encl_mm->mm);
+
+ break;
+ }
+
+ srcu_read_unlock(&encl->srcu, idx);
+
+ /*
+ * In the rare case that there isn't an mm associated with
+ * the enclave, set memcg to the current active mem_cgroup.
+ * This will be the root mem_cgroup if there is no active
+ * mem_cgroup.
+ */
+ if (!memcg)
+ return get_mem_cgroup_from_mm(NULL);
+
+ return memcg;
+}
+
+/**
+ * sgx_encl_alloc_backing() - allocate a new backing storage page
+ * @encl: an enclave pointer
+ * @page_index: enclave page index
+ * @backing: data for accessing backing storage for the page
+ *
+ * When called from ksgxd, 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.
+ *
+ * Return:
+ * 0 on success,
+ * -errno otherwise.
+ */
+int sgx_encl_alloc_backing(struct sgx_encl *encl, unsigned long page_index,
+ struct sgx_backing *backing)
+{
+ struct mem_cgroup *encl_memcg = sgx_encl_get_mem_cgroup(encl);
+ struct mem_cgroup *memcg = set_active_memcg(encl_memcg);
+ int ret;
+
+ ret = sgx_encl_get_backing(encl, page_index, backing);
+
+ set_active_memcg(memcg);
+ mem_cgroup_put(encl_memcg);
+
+ return ret;
+}
+
+/**
+ * sgx_encl_lookup_backing() - retrieve an existing backing storage page
+ * @encl: an enclave pointer
+ * @page_index: enclave page index
+ * @backing: data for accessing backing storage for the page
+ *
+ * Retrieve a backing page for loading data back into an EPC page with ELDU.
+ * It is the caller's responsibility to ensure that it is appropriate to use
+ * sgx_encl_lookup_backing() rather than sgx_encl_alloc_backing(). If lookup is
+ * not used correctly, this will cause an allocation which is not accounted for.
+ *
+ * Return:
+ * 0 on success,
+ * -errno otherwise.
+ */
+int sgx_encl_lookup_backing(struct sgx_encl *encl, unsigned long page_index,
+ struct sgx_backing *backing)
+{
+ return sgx_encl_get_backing(encl, page_index, backing);
+}
+
/**
* sgx_encl_put_backing() - Unpin the backing storage
* @backing: data for accessing backing storage for the page
diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
index d44e7372151f..332ef3568267 100644
--- a/arch/x86/kernel/cpu/sgx/encl.h
+++ b/arch/x86/kernel/cpu/sgx/encl.h
@@ -103,10 +103,13 @@ 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);
-int sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index,
- struct sgx_backing *backing);
+int sgx_encl_lookup_backing(struct sgx_encl *encl, unsigned long page_index,
+ struct sgx_backing *backing);
+int sgx_encl_alloc_backing(struct sgx_encl *encl, unsigned long page_index,
+ struct sgx_backing *backing);
void sgx_encl_put_backing(struct sgx_backing *backing);
int sgx_encl_test_and_clear_young(struct mm_struct *mm,
struct sgx_encl_page *page);
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index ab4ec54bbdd9..a78652d43e61 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -313,7 +313,7 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
sgx_encl_put_backing(backing);
if (!encl->secs_child_cnt && test_bit(SGX_ENCL_INITIALIZED, &encl->flags)) {
- ret = sgx_encl_get_backing(encl, PFN_DOWN(encl->size),
+ ret = sgx_encl_alloc_backing(encl, PFN_DOWN(encl->size),
&secs_backing);
if (ret)
goto out;
@@ -384,7 +384,7 @@ static void sgx_reclaim_pages(void)
page_index = PFN_DOWN(encl_page->desc - encl_page->encl->base);
mutex_lock(&encl_page->encl->lock);
- ret = sgx_encl_get_backing(encl_page->encl, page_index, &backing[i]);
+ ret = sgx_encl_alloc_backing(encl_page->encl, page_index, &backing[i]);
if (ret) {
mutex_unlock(&encl_page->encl->lock);
goto skip;
@@ -475,6 +475,11 @@ static bool __init sgx_page_reclaimer_init(void)
return true;
}
+bool current_is_ksgxd(void)
+{
+ return current == ksgxd_tsk;
+}
+
static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)
{
struct sgx_numa_node *node = &sgx_numa_nodes[nid];
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