[PATCH 00/26] Add Cgroup support for SGX EPC memory

[PATCH 00/26] Add Cgroup support for SGX EPC memory

[Kristen Carlson Accardi]

Utilize the Miscellaneous cgroup controller to regulate the distribution
of SGX EPC memory, which is a subset of system RAM that is used to provide
SGX-enabled applications with protected memory, and is otherwise inaccessible.

SGX EPC memory allocations are separate from normal RAM allocations,
and is managed solely by the SGX subsystem. The existing cgroup memory
controller cannot be used to limit or account for SGX EPC memory.

This patchset implements the support for sgx_epc memory within the 
misc cgroup controller, and then utilizes the misc cgroup controller
to provide support for setting the total system capacity, max limit
per cgroup, and events.

This work was originally authored by Sean Christopherson a few years ago,
and was modified to work with more recent kernels, and to utilize the
misc cgroup controller rather than a custom controller. It is currently
based on top of the MCA patches.

Here's the MCA patchset for reference.
https://lore.kernel.org/linux-sgx/2d52c8c4-8ed0-6df2-2911-da5b9fcc9ae4@intel.com/T/#t

The patchset adds support for multiple LRUs to track both reclaimable
EPC pages (i.e. pages the reclaimer knows about), as well as unreclaimable
EPC pages (i.e. pages which the reclaimer isn't aware of, such as va pages).
These pages are assigned to an LRU, as well as an enclave, so that an
enclave's full EPC usage can be tracked, and limited to a max value. During
OOM events, an enclave can be have its memory zapped, and all the EPC pages
not tracked by the reclaimer can be freed.

I appreciate your comments and feedback.

Kristen Carlson Accardi (13):
  x86/sgx: Add 'struct sgx_epc_lru' to encapsulate lru list(s)
  x86/sgx: Use sgx_epc_lru for existing active page list
  x86/sgx: Track epc pages on reclaimable or unreclaimable lists
  cgroup/misc: Add notifier block list support for css events
  cgroup/misc: Expose root_misc
  cgroup/misc: Expose parent_misc()
  cgroup/misc: allow users of misc cgroup to read specific cgroup usage
  cgroup/misc: allow misc cgroup consumers to read the max value
  cgroup/misc: Add private per cgroup data to struct misc_cg
  cgroup/misc: Add tryget functionality for misc controller
  cgroup/misc: Add SGX EPC resource type
  x86/sgx: Add support for misc cgroup controller
  Docs/x86/sgx: Add description for cgroup support

Sean Christopherson (13):
  x86/sgx: Call cond_resched() at the end of sgx_reclaim_pages()
  x86/sgx: Store struct sgx_encl when allocating new va pages
  x86/sgx: Introduce RECLAIM_IN_PROGRESS flag for EPC pages
  x86/sgx: Use a list to track to-be-reclaimed pages during reclaim
  x86/sgx: Add EPC page flags to identify type of page
  x86/sgx: Allow reclaiming up to 32 pages, but scan 16 by default
  x86/sgx: Return the number of EPC pages that were successfully
    reclaimed
  x86/sgx: Add option to ignore age of page during EPC reclaim
  x86/sgx: Add helper to retrieve SGX EPC LRU given an EPC page
  x86/sgx: Prepare for multiple LRUs
  x86/sgx: Expose sgx_reclaim_pages() for use by EPC cgroup
  x86/sgx: Add helper to grab pages from an arbitrary EPC LRU
  x86/sgx: Add EPC OOM path to forcefully reclaim EPC

 Documentation/x86/sgx.rst            |  77 ++++
 arch/x86/Kconfig                     |  13 +
 arch/x86/kernel/cpu/sgx/Makefile     |   1 +
 arch/x86/kernel/cpu/sgx/encl.c       |  89 ++++-
 arch/x86/kernel/cpu/sgx/encl.h       |   4 +-
 arch/x86/kernel/cpu/sgx/epc_cgroup.c | 561 +++++++++++++++++++++++++++
 arch/x86/kernel/cpu/sgx/epc_cgroup.h |  59 +++
 arch/x86/kernel/cpu/sgx/ioctl.c      |  13 +-
 arch/x86/kernel/cpu/sgx/main.c       | 405 +++++++++++++++----
 arch/x86/kernel/cpu/sgx/sgx.h        |  96 ++++-
 arch/x86/kernel/cpu/sgx/virt.c       |  28 +-
 include/linux/misc_cgroup.h          |  71 ++++
 kernel/cgroup/misc.c                 | 145 ++++++-
 13 files changed, 1446 insertions(+), 116 deletions(-)
 create mode 100644 arch/x86/kernel/cpu/sgx/epc_cgroup.c
 create mode 100644 arch/x86/kernel/cpu/sgx/epc_cgroup.h

-- 
2.37.3

[PATCH 01/26] x86/sgx: Call cond_resched() at the end of sgx_reclaim_pages()

[Kristen Carlson Accardi]

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

In order to avoid repetition of cond_resched() in ksgxd() and
sgx_alloc_epc_page(), move the invocation of post-reclaim cond_resched()
inside sgx_reclaim_pages(). Except in the case of sgx_reclaim_direct(),
sgx_reclaim_pages() is always called in a loop and is always followed
by a call to cond_resched().  This will hold true for the EPC cgroup
as well, which adds even more calls to sgx_reclaim_pages() and thus
cond_resched(). Calls to sgx_reclaim_direct() may be performance
sensitive. Allow sgx_reclaim_direct() to avoid the cond_resched()
call by moving the original sgx_reclaim_pages() call to
__sgx_reclaim_pages() and then have sgx_reclaim_pages() become a
wrapper around that call with a cond_resched().

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/main.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 160c8dbee0ab..ffce6fc70a1f 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -287,7 +287,7 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
  * problematic as it would increase the lock contention too much, which would
  * halt forward progress.
  */
-static void sgx_reclaim_pages(void)
+static void __sgx_reclaim_pages(void)
 {
 	struct sgx_epc_page *chunk[SGX_NR_TO_SCAN];
 	struct sgx_backing backing[SGX_NR_TO_SCAN];
@@ -369,6 +369,12 @@ static void sgx_reclaim_pages(void)
 	}
 }
 
+static void sgx_reclaim_pages(void)
+{
+	__sgx_reclaim_pages();
+	cond_resched();
+}
+
 static bool sgx_should_reclaim(unsigned long watermark)
 {
 	return atomic_long_read(&sgx_nr_free_pages) < watermark &&
@@ -378,12 +384,14 @@ static bool sgx_should_reclaim(unsigned long watermark)
 /*
  * sgx_reclaim_direct() should be called (without enclave's mutex held)
  * in locations where SGX memory resources might be low and might be
- * needed in order to make forward progress.
+ * needed in order to make forward progress. This call to
+ * __sgx_reclaim_pages() avoids the cond_resched() in sgx_reclaim_pages()
+ * to improve performance.
  */
 void sgx_reclaim_direct(void)
 {
 	if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
-		sgx_reclaim_pages();
+		__sgx_reclaim_pages();
 }
 
 static int ksgxd(void *p)
@@ -410,8 +418,6 @@ static int ksgxd(void *p)
 
 		if (sgx_should_reclaim(SGX_NR_HIGH_PAGES))
 			sgx_reclaim_pages();
-
-		cond_resched();
 	}
 
 	return 0;
@@ -582,7 +588,6 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
 		}
 
 		sgx_reclaim_pages();
-		cond_resched();
 	}
 
 	if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
-- 
2.37.3

[PATCH 02/26] x86/sgx: Store struct sgx_encl when allocating new va pages

[Kristen Carlson Accardi]

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

When allocating new va pages, pass the struct sgx_encl of the enclave
that is allocating the page. sgx_alloc_epc_page() will store this
value in the encl_owner field of the struct sgx_epc_page. In a later
patch, version array pages will be placed in an unreclaimable queue,
and then when the cgroup max limit is reached and there are no more
reclaimable pages and the enclave must be oom killed, all the
va pages associated with that enclave can be uncharged and freed.

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/encl.c  | 5 +++--
 arch/x86/kernel/cpu/sgx/encl.h  | 2 +-
 arch/x86/kernel/cpu/sgx/ioctl.c | 2 +-
 arch/x86/kernel/cpu/sgx/sgx.h   | 2 ++
 4 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index f40d64206ded..4eaf9d21e71b 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -1193,6 +1193,7 @@ void sgx_zap_enclave_ptes(struct sgx_encl *encl, unsigned long addr)
 
 /**
  * sgx_alloc_va_page() - Allocate a Version Array (VA) page
+ * @encl:    The enclave that this page is allocated to.
  * @reclaim: Reclaim EPC pages directly if none available. Enclave
  *           mutex should not be held if this is set.
  *
@@ -1202,12 +1203,12 @@ void sgx_zap_enclave_ptes(struct sgx_encl *encl, unsigned long addr)
  *   a VA page,
  *   -errno otherwise
  */
-struct sgx_epc_page *sgx_alloc_va_page(bool reclaim)
+struct sgx_epc_page *sgx_alloc_va_page(struct sgx_encl *encl, bool reclaim)
 {
 	struct sgx_epc_page *epc_page;
 	int ret;
 
-	epc_page = sgx_alloc_epc_page(NULL, reclaim);
+	epc_page = sgx_alloc_epc_page(encl, reclaim);
 	if (IS_ERR(epc_page))
 		return ERR_CAST(epc_page);
 
diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
index f94ff14c9486..831d63f80f5a 100644
--- a/arch/x86/kernel/cpu/sgx/encl.h
+++ b/arch/x86/kernel/cpu/sgx/encl.h
@@ -116,7 +116,7 @@ struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
 					  unsigned long offset,
 					  u64 secinfo_flags);
 void sgx_zap_enclave_ptes(struct sgx_encl *encl, unsigned long addr);
-struct sgx_epc_page *sgx_alloc_va_page(bool reclaim);
+struct sgx_epc_page *sgx_alloc_va_page(struct sgx_encl *encl, bool reclaim);
 unsigned int sgx_alloc_va_slot(struct sgx_va_page *va_page);
 void sgx_free_va_slot(struct sgx_va_page *va_page, unsigned int offset);
 bool sgx_va_page_full(struct sgx_va_page *va_page);
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index ebe79d60619f..9a1bb3c3211a 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -30,7 +30,7 @@ struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl, bool reclaim)
 		if (!va_page)
 			return ERR_PTR(-ENOMEM);
 
-		va_page->epc_page = sgx_alloc_va_page(reclaim);
+		va_page->epc_page = sgx_alloc_va_page(encl, reclaim);
 		if (IS_ERR(va_page->epc_page)) {
 			err = ERR_CAST(va_page->epc_page);
 			kfree(va_page);
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index d16a8baa28d4..efb10eacd3aa 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -39,6 +39,8 @@ struct sgx_epc_page {
 		struct sgx_encl_page *encl_owner;
 		/* Use when SGX_EPC_PAGE_KVM_GUEST set in ->flags: */
 		void __user *vepc_vaddr;
+
+		struct sgx_encl *encl;
 	};
 	struct list_head list;
 };
-- 
2.37.3

[PATCH 03/26] x86/sgx: Add 'struct sgx_epc_lru' to encapsulate lru list(s)

[Kristen Carlson Accardi]

Introduce a data structure to 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@intel.com>
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Cc: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kernel/cpu/sgx/sgx.h | 45 +++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index efb10eacd3aa..aac7d4feb0fa 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -91,6 +91,51 @@ 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;
+	struct list_head unreclaimable;
+};
+
+static inline void sgx_lru_init(struct sgx_epc_lru *lru)
+{
+	spin_lock_init(&lru->lock);
+	INIT_LIST_HEAD(&lru->reclaimable);
+	INIT_LIST_HEAD(&lru->unreclaimable);
+}
+
+/*
+ * Must be called with queue lock acquired
+ */
+static inline void __sgx_epc_page_list_push(struct list_head *list, struct sgx_epc_page *page)
+{
+	list_add_tail(&page->list, list);
+}
+
+/*
+ * Must be called with queue lock acquired
+ */
+static inline struct sgx_epc_page * __sgx_epc_page_list_pop(struct list_head *list)
+{
+	struct sgx_epc_page *epc_page;
+
+	if (list_empty(list))
+		return NULL;
+
+	epc_page = list_first_entry(list, struct sgx_epc_page, list);
+	list_del_init(&epc_page->list);
+	return epc_page;
+}
+
+#define sgx_epc_pop_reclaimable(lru) \
+	__sgx_epc_page_list_pop(&(lru)->reclaimable)
+#define sgx_epc_push_reclaimable(lru, page) \
+	__sgx_epc_page_list_push(&(lru)->reclaimable, page)
+#define sgx_epc_pop_unreclaimable(lru) \
+	__sgx_epc_page_list_pop(&(lru)->unreclaimable)
+#define sgx_epc_push_unreclaimable(lru, page) \
+	__sgx_epc_page_list_push(&(lru)->unreclaimable, page)
+
 struct sgx_epc_page *__sgx_alloc_epc_page(void);
 void sgx_free_epc_page(struct sgx_epc_page *page);
 
-- 
2.37.3

[PATCH 04/26] x86/sgx: Use sgx_epc_lru for existing active page list

[Kristen Carlson Accardi]

Replace the existing sgx_active_page_list and its spinlock with
a global sgx_epc_lru struct.

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/main.c | 39 +++++++++++++++++-----------------
 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index ffce6fc70a1f..aa938e4d4a73 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);
 
@@ -298,14 +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))
+		epc_page = sgx_epc_pop_reclaimable(&sgx_global_lru);
+		if (!epc_page)
 			break;
 
-		epc_page = list_first_entry(&sgx_active_page_list,
-					    struct sgx_epc_page, list);
-		list_del_init(&epc_page->list);
 		encl_page = epc_page->encl_owner;
 
 		if (kref_get_unless_zero(&encl_page->encl->refcount) != 0)
@@ -316,7 +313,7 @@ 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 +336,9 @@ 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);
+		sgx_epc_push_reclaimable(&sgx_global_lru, epc_page);
+		spin_unlock(&sgx_global_lru.lock);
 
 		kref_put(&encl_page->encl->refcount, sgx_encl_release);
 
@@ -378,7 +375,7 @@ 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);
 }
 
 /*
@@ -433,6 +430,8 @@ static bool __init sgx_page_reclaimer_init(void)
 
 	ksgxd_tsk = tsk;
 
+	sgx_lru_init(&sgx_global_lru);
+
 	return true;
 }
 
@@ -508,10 +507,10 @@ 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);
+	sgx_epc_push_reclaimable(&sgx_global_lru, page);
+	spin_unlock(&sgx_global_lru.lock);
 }
 
 /**
@@ -526,18 +525,18 @@ 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;
 }
@@ -574,7 +573,7 @@ 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) {
-- 
2.37.3

[PATCH 05/26] x86/sgx: Track epc pages on reclaimable or unreclaimable lists

[Kristen Carlson Accardi]

Replace functions sgx_mark_page_reclaimable() and
sgx_unmark_page_reclaimable() with sgx_record_epc_page() and
sgx_drop_epc_page(). sgx_record_epc_page() wil add the epc_page
to the correct "reclaimable" or "unreclaimable" list in the
sgx_epc_lru struct. sgx_drop_epc_page() will delete the page
from the sgx_epc_lru list. Tracking pages that are not tracked by
the reclaimer in the LRU's "unreclaimable" list allows an OOM event
to cause all the pages in use by an enclave to be freed, regardless
of whether they were reclaimable pages or not.

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/encl.c  | 10 +++++++---
 arch/x86/kernel/cpu/sgx/ioctl.c | 11 +++++++----
 arch/x86/kernel/cpu/sgx/main.c  | 26 +++++++++++++++-----------
 arch/x86/kernel/cpu/sgx/sgx.h   |  4 ++--
 arch/x86/kernel/cpu/sgx/virt.c  | 28 ++++++++++++++++++++--------
 5 files changed, 51 insertions(+), 28 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 4eaf9d21e71b..4683da9ef4f1 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -252,6 +252,7 @@ static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl,
 		epc_page = sgx_encl_eldu(&encl->secs, NULL);
 		if (IS_ERR(epc_page))
 			return ERR_CAST(epc_page);
+		sgx_record_epc_page(epc_page, 0);
 	}
 
 	epc_page = sgx_encl_eldu(entry, encl->secs.epc_page);
@@ -259,7 +260,7 @@ static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl,
 		return ERR_CAST(epc_page);
 
 	encl->secs_child_cnt++;
-	sgx_mark_page_reclaimable(entry->epc_page);
+	sgx_record_epc_page(entry->epc_page, SGX_EPC_PAGE_RECLAIMER_TRACKED);
 
 	return entry;
 }
@@ -375,7 +376,7 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
 	encl_page->type = SGX_PAGE_TYPE_REG;
 	encl->secs_child_cnt++;
 
-	sgx_mark_page_reclaimable(encl_page->epc_page);
+	sgx_record_epc_page(encl_page->epc_page, SGX_EPC_PAGE_RECLAIMER_TRACKED);
 
 	phys_addr = sgx_get_epc_phys_addr(epc_page);
 	/*
@@ -687,7 +688,7 @@ void sgx_encl_release(struct kref *ref)
 			 * The page and its radix tree entry cannot be freed
 			 * if the page is being held by the reclaimer.
 			 */
-			if (sgx_unmark_page_reclaimable(entry->epc_page))
+			if (sgx_drop_epc_page(entry->epc_page))
 				continue;
 
 			sgx_encl_free_epc_page(entry->epc_page);
@@ -703,6 +704,7 @@ void sgx_encl_release(struct kref *ref)
 	xa_destroy(&encl->page_array);
 
 	if (!encl->secs_child_cnt && encl->secs.epc_page) {
+		sgx_drop_epc_page(encl->secs.epc_page);
 		sgx_encl_free_epc_page(encl->secs.epc_page);
 		encl->secs.epc_page = NULL;
 	}
@@ -711,6 +713,7 @@ void sgx_encl_release(struct kref *ref)
 		va_page = list_first_entry(&encl->va_pages, struct sgx_va_page,
 					   list);
 		list_del(&va_page->list);
+		sgx_drop_epc_page(va_page->epc_page);
 		sgx_encl_free_epc_page(va_page->epc_page);
 		kfree(va_page);
 	}
@@ -1218,6 +1221,7 @@ struct sgx_epc_page *sgx_alloc_va_page(struct sgx_encl *encl, bool reclaim)
 		sgx_encl_free_epc_page(epc_page);
 		return ERR_PTR(-EFAULT);
 	}
+	sgx_record_epc_page(epc_page, 0);
 
 	return epc_page;
 }
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 9a1bb3c3211a..aca80a3f38a1 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -48,6 +48,7 @@ void sgx_encl_shrink(struct sgx_encl *encl, struct sgx_va_page *va_page)
 	encl->page_cnt--;
 
 	if (va_page) {
+		sgx_drop_epc_page(va_page->epc_page);
 		sgx_encl_free_epc_page(va_page->epc_page);
 		list_del(&va_page->list);
 		kfree(va_page);
@@ -113,6 +114,8 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
 	encl->attributes = secs->attributes;
 	encl->attributes_mask = SGX_ATTR_DEBUG | SGX_ATTR_MODE64BIT | SGX_ATTR_KSS;
 
+	sgx_record_epc_page(encl->secs.epc_page, 0);
+
 	/* Set only after completion, as encl->lock has not been taken. */
 	set_bit(SGX_ENCL_CREATED, &encl->flags);
 
@@ -322,7 +325,7 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src,
 			goto err_out;
 	}
 
-	sgx_mark_page_reclaimable(encl_page->epc_page);
+	sgx_record_epc_page(encl_page->epc_page, SGX_EPC_PAGE_RECLAIMER_TRACKED);
 	mutex_unlock(&encl->lock);
 	mmap_read_unlock(current->mm);
 	return ret;
@@ -958,7 +961,7 @@ static long sgx_enclave_modify_types(struct sgx_encl *encl,
 			 * Prevent page from being reclaimed while mutex
 			 * is released.
 			 */
-			if (sgx_unmark_page_reclaimable(entry->epc_page)) {
+			if (sgx_drop_epc_page(entry->epc_page)) {
 				ret = -EAGAIN;
 				goto out_entry_changed;
 			}
@@ -973,7 +976,7 @@ static long sgx_enclave_modify_types(struct sgx_encl *encl,
 
 			mutex_lock(&encl->lock);
 
-			sgx_mark_page_reclaimable(entry->epc_page);
+			sgx_record_epc_page(entry->epc_page, SGX_EPC_PAGE_RECLAIMER_TRACKED);
 		}
 
 		/* Change EPC type */
@@ -1130,7 +1133,7 @@ static long sgx_encl_remove_pages(struct sgx_encl *encl,
 			goto out_unlock;
 		}
 
-		if (sgx_unmark_page_reclaimable(entry->epc_page)) {
+		if (sgx_drop_epc_page(entry->epc_page)) {
 			ret = -EBUSY;
 			goto out_unlock;
 		}
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index aa938e4d4a73..3b09433ffd85 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -262,7 +262,7 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
 			goto out;
 
 		sgx_encl_ewb(encl->secs.epc_page, &secs_backing);
-
+		sgx_drop_epc_page(encl->secs.epc_page);
 		sgx_encl_free_epc_page(encl->secs.epc_page);
 		encl->secs.epc_page = NULL;
 
@@ -499,31 +499,35 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
 }
 
 /**
- * sgx_mark_page_reclaimable() - Mark a page as reclaimable
+ * sgx_record_epc_page() - Add a page to the LRU tracking
  * @page:	EPC page
  *
- * Mark a page as reclaimable and add it to the active page list. Pages
- * are automatically removed from the active list when freed.
+ * Mark a page with the specified flags and add it to the appropriate
+ * (un)reclaimable list.
  */
-void sgx_mark_page_reclaimable(struct sgx_epc_page *page)
+void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
 {
 	spin_lock(&sgx_global_lru.lock);
-	page->flags |= SGX_EPC_PAGE_RECLAIMER_TRACKED;
-	sgx_epc_push_reclaimable(&sgx_global_lru, page);
+	WARN_ON(page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED);
+	page->flags |= flags;
+	if (flags & SGX_EPC_PAGE_RECLAIMER_TRACKED)
+		sgx_epc_push_reclaimable(&sgx_global_lru, page);
+	else
+		sgx_epc_push_unreclaimable(&sgx_global_lru, page);
 	spin_unlock(&sgx_global_lru.lock);
 }
 
 /**
- * sgx_unmark_page_reclaimable() - Remove a page from the reclaim list
+ * sgx_drop_epc_page() - Remove a page from a LRU list
  * @page:	EPC page
  *
- * Clear the reclaimable flag and remove the page from the active page list.
+ * Clear the reclaimable flag if set and remove the page from its LRU.
  *
  * Return:
  *   0 on success,
  *   -EBUSY if the page is in the process of being reclaimed
  */
-int sgx_unmark_page_reclaimable(struct sgx_epc_page *page)
+int sgx_drop_epc_page(struct sgx_epc_page *page)
 {
 	spin_lock(&sgx_global_lru.lock);
 	if (page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED) {
@@ -533,9 +537,9 @@ int sgx_unmark_page_reclaimable(struct sgx_epc_page *page)
 			return -EBUSY;
 		}
 
-		list_del(&page->list);
 		page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
 	}
+	list_del(&page->list);
 	spin_unlock(&sgx_global_lru.lock);
 
 	return 0;
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index aac7d4feb0fa..969606615211 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -140,8 +140,8 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void);
 void sgx_free_epc_page(struct sgx_epc_page *page);
 
 void sgx_reclaim_direct(void);
-void sgx_mark_page_reclaimable(struct sgx_epc_page *page);
-int sgx_unmark_page_reclaimable(struct sgx_epc_page *page);
+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);
 
 void sgx_ipi_cb(void *info);
diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c
index 776ae5c1c032..0eabc4db91d0 100644
--- a/arch/x86/kernel/cpu/sgx/virt.c
+++ b/arch/x86/kernel/cpu/sgx/virt.c
@@ -64,6 +64,8 @@ static int __sgx_vepc_fault(struct sgx_vepc *vepc,
 		goto err_delete;
 	}
 
+	sgx_record_epc_page(epc_page, 0);
+
 	return 0;
 
 err_delete:
@@ -148,6 +150,7 @@ static int sgx_vepc_free_page(struct sgx_epc_page *epc_page)
 		return ret;
 	}
 
+	sgx_drop_epc_page(epc_page);
 	sgx_free_epc_page(epc_page);
 	return 0;
 }
@@ -220,8 +223,15 @@ static int sgx_vepc_release(struct inode *inode, struct file *file)
 		 * have been removed, the SECS page must have a child on
 		 * another instance.
 		 */
-		if (sgx_vepc_free_page(epc_page))
+		if (sgx_vepc_free_page(epc_page)) {
+			/*
+			 * Drop the page before adding it to the list of SECS
+			 * pages.  Moving the page off the unreclaimable list
+			 * needs to be done under the LRU's spinlock.
+			 */
+			sgx_drop_epc_page(epc_page);
 			list_add_tail(&epc_page->list, &secs_pages);
+		}
 
 		xa_erase(&vepc->page_array, index);
 	}
@@ -236,15 +246,17 @@ static int sgx_vepc_release(struct inode *inode, struct file *file)
 	mutex_lock(&zombie_secs_pages_lock);
 	list_for_each_entry_safe(epc_page, tmp, &zombie_secs_pages, list) {
 		/*
-		 * Speculatively remove the page from the list of zombies,
-		 * if the page is successfully EREMOVE'd it will be added to
-		 * the list of free pages.  If EREMOVE fails, throw the page
-		 * on the local list, which will be spliced on at the end.
+		 * If EREMOVE fails, throw the page on the local list, which
+		 * will be spliced on at the end.
+		 *
+		 * Note, this abuses sgx_drop_epc_page() to delete the page off
+		 * the list of zombies, but this is a very rare path (probably
+		 * never hit in production).  It's not worth special casing the
+		 * free path for this super rare case just to avoid taking the
+		 * LRU's spinlock.
 		 */
-		list_del(&epc_page->list);
-
 		if (sgx_vepc_free_page(epc_page))
-			list_add_tail(&epc_page->list, &secs_pages);
+			list_move_tail(&epc_page->list, &secs_pages);
 	}
 
 	if (!list_empty(&secs_pages))
-- 
2.37.3

[PATCH 06/26] x86/sgx: Introduce RECLAIM_IN_PROGRESS flag for EPC pages

[Kristen Carlson Accardi]

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

Keep track of whether the EPC page is in the middle of being reclaimed
and do not delete the page off the it's LRU if it has not yet finished
being reclaimed.

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/main.c | 14 +++++++++-----
 arch/x86/kernel/cpu/sgx/sgx.h  |  4 ++++
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 3b09433ffd85..8c451071fa91 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -305,13 +305,15 @@ static void __sgx_reclaim_pages(void)
 
 		encl_page = epc_page->encl_owner;
 
-		if (kref_get_unless_zero(&encl_page->encl->refcount) != 0)
+		if (kref_get_unless_zero(&encl_page->encl->refcount) != 0) {
+			epc_page->flags |= SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
 			chunk[cnt++] = epc_page;
-		else
+		} else {
 			/* The owner is freeing the page. No need to add the
 			 * page back to the list of reclaimable pages.
 			 */
 			epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
+		}
 	}
 	spin_unlock(&sgx_global_lru.lock);
 
@@ -337,6 +339,7 @@ static void __sgx_reclaim_pages(void)
 
 skip:
 		spin_lock(&sgx_global_lru.lock);
+		epc_page->flags &= ~SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
 		sgx_epc_push_reclaimable(&sgx_global_lru, epc_page);
 		spin_unlock(&sgx_global_lru.lock);
 
@@ -360,7 +363,8 @@ static void __sgx_reclaim_pages(void)
 		sgx_reclaimer_write(epc_page, &backing[i]);
 
 		kref_put(&encl_page->encl->refcount, sgx_encl_release);
-		epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
+		epc_page->flags &= ~(SGX_EPC_PAGE_RECLAIMER_TRACKED |
+				     SGX_EPC_PAGE_RECLAIM_IN_PROGRESS);
 
 		sgx_free_epc_page(epc_page);
 	}
@@ -508,7 +512,7 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
 void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
 {
 	spin_lock(&sgx_global_lru.lock);
-	WARN_ON(page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED);
+	WARN_ON(page->flags & SGX_EPC_PAGE_RECLAIM_FLAGS);
 	page->flags |= flags;
 	if (flags & SGX_EPC_PAGE_RECLAIMER_TRACKED)
 		sgx_epc_push_reclaimable(&sgx_global_lru, page);
@@ -532,7 +536,7 @@ int sgx_drop_epc_page(struct sgx_epc_page *page)
 	spin_lock(&sgx_global_lru.lock);
 	if (page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED) {
 		/* The page is being reclaimed. */
-		if (list_empty(&page->list)) {
+		if (page->flags & SGX_EPC_PAGE_RECLAIM_IN_PROGRESS) {
 			spin_unlock(&sgx_global_lru.lock);
 			return -EBUSY;
 		}
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 969606615211..04ca644928a8 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -30,6 +30,10 @@
 #define SGX_EPC_PAGE_IS_FREE		BIT(1)
 /* Pages allocated for KVM guest */
 #define SGX_EPC_PAGE_KVM_GUEST		BIT(2)
+/* page flag to indicate reclaim is in progress */
+#define SGX_EPC_PAGE_RECLAIM_IN_PROGRESS BIT(3)
+#define SGX_EPC_PAGE_RECLAIM_FLAGS	(SGX_EPC_PAGE_RECLAIMER_TRACKED | \
+					 SGX_EPC_PAGE_RECLAIM_IN_PROGRESS)
 
 struct sgx_epc_page {
 	unsigned int section;
-- 
2.37.3

[PATCH 07/26] x86/sgx: Use a list to track to-be-reclaimed pages during reclaim

[Kristen Carlson Accardi]

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

Change sgx_reclaim_pages() to use a list rather than an array for
storing the epc_pages which will be reclaimed. This change is needed
to transition to the LRU implementation for EPC cgroup support.

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/main.c | 44 ++++++++++++++++------------------
 arch/x86/kernel/cpu/sgx/sgx.h  | 28 ++++++++++++++++++++++
 2 files changed, 48 insertions(+), 24 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 8c451071fa91..c76a53b63fa2 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -288,18 +288,17 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
  */
 static void __sgx_reclaim_pages(void)
 {
-	struct sgx_epc_page *chunk[SGX_NR_TO_SCAN];
 	struct sgx_backing backing[SGX_NR_TO_SCAN];
+	struct sgx_epc_page *epc_page, *tmp;
 	struct sgx_encl_page *encl_page;
-	struct sgx_epc_page *epc_page;
 	pgoff_t page_index;
-	int cnt = 0;
+	LIST_HEAD(iso);
 	int ret;
 	int i;
 
 	spin_lock(&sgx_global_lru.lock);
 	for (i = 0; i < SGX_NR_TO_SCAN; i++) {
-		epc_page = sgx_epc_pop_reclaimable(&sgx_global_lru);
+		epc_page = sgx_epc_peek_reclaimable(&sgx_global_lru);
 		if (!epc_page)
 			break;
 
@@ -307,18 +306,22 @@ static void __sgx_reclaim_pages(void)
 
 		if (kref_get_unless_zero(&encl_page->encl->refcount) != 0) {
 			epc_page->flags |= SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
-			chunk[cnt++] = epc_page;
+			list_move_tail(&epc_page->list, &iso);
 		} else {
-			/* The owner is freeing the page. No need to add the
-			 * page back to the list of reclaimable pages.
+			/* The owner is freeing the page, remove it from the
+			 * LRU list
 			 */
 			epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
+			list_del_init(&epc_page->list);
 		}
 	}
 	spin_unlock(&sgx_global_lru.lock);
 
-	for (i = 0; i < cnt; i++) {
-		epc_page = chunk[i];
+	if (list_empty(&iso))
+		return;
+
+	i = 0;
+	list_for_each_entry_safe(epc_page, tmp, &iso, list) {
 		encl_page = epc_page->encl_owner;
 
 		if (!sgx_reclaimer_age(epc_page))
@@ -333,6 +336,7 @@ static void __sgx_reclaim_pages(void)
 			goto skip;
 		}
 
+		i++;
 		encl_page->desc |= SGX_ENCL_PAGE_BEING_RECLAIMED;
 		mutex_unlock(&encl_page->encl->lock);
 		continue;
@@ -340,27 +344,19 @@ static void __sgx_reclaim_pages(void)
 skip:
 		spin_lock(&sgx_global_lru.lock);
 		epc_page->flags &= ~SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
-		sgx_epc_push_reclaimable(&sgx_global_lru, epc_page);
+		sgx_epc_move_reclaimable(&sgx_global_lru, epc_page);
 		spin_unlock(&sgx_global_lru.lock);
 
 		kref_put(&encl_page->encl->refcount, sgx_encl_release);
-
-		chunk[i] = NULL;
-	}
-
-	for (i = 0; i < cnt; i++) {
-		epc_page = chunk[i];
-		if (epc_page)
-			sgx_reclaimer_block(epc_page);
 	}
 
-	for (i = 0; i < cnt; i++) {
-		epc_page = chunk[i];
-		if (!epc_page)
-			continue;
-
+	list_for_each_entry(epc_page, &iso, list)
+		sgx_reclaimer_block(epc_page);
+ 
+	i = 0;
+	list_for_each_entry_safe(epc_page, tmp, &iso, list) {
 		encl_page = epc_page->encl_owner;
-		sgx_reclaimer_write(epc_page, &backing[i]);
+		sgx_reclaimer_write(epc_page, &backing[i++]);
 
 		kref_put(&encl_page->encl->refcount, sgx_encl_release);
 		epc_page->flags &= ~(SGX_EPC_PAGE_RECLAIMER_TRACKED |
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 04ca644928a8..29c0981d6310 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -116,6 +116,14 @@ static inline void __sgx_epc_page_list_push(struct list_head *list, struct sgx_e
 	list_add_tail(&page->list, list);
 }
 
+/*
+ * Must be called with queue lock acquired
+ */
+static inline void __sgx_epc_page_list_move(struct list_head *list, struct sgx_epc_page *page)
+{
+	list_move_tail(&page->list, list);
+}
+
 /*
  * Must be called with queue lock acquired
  */
@@ -131,14 +139,34 @@ static inline struct sgx_epc_page * __sgx_epc_page_list_pop(struct list_head *li
 	return epc_page;
 }
 
+/*
+ * Must be called with queue lock acquired
+ */
+static inline struct sgx_epc_page * __sgx_epc_page_list_peek(struct list_head *list)
+{
+	struct sgx_epc_page *epc_page;
+
+	if (list_empty(list))
+		return NULL;
+
+	epc_page = list_first_entry(list, struct sgx_epc_page, list);
+	return epc_page;
+}
+
 #define sgx_epc_pop_reclaimable(lru) \
 	__sgx_epc_page_list_pop(&(lru)->reclaimable)
 #define sgx_epc_push_reclaimable(lru, page) \
 	__sgx_epc_page_list_push(&(lru)->reclaimable, page)
+#define sgx_epc_peek_reclaimable(lru) \
+	__sgx_epc_page_list_peek(&(lru)->reclaimable)
+#define sgx_epc_move_reclaimable(lru, page) \
+	__sgx_epc_page_list_move(&(lru)->reclaimable, page)
 #define sgx_epc_pop_unreclaimable(lru) \
 	__sgx_epc_page_list_pop(&(lru)->unreclaimable)
 #define sgx_epc_push_unreclaimable(lru, page) \
 	__sgx_epc_page_list_push(&(lru)->unreclaimable, page)
+#define sgx_epc_peek_unreclaimable(lru) \
+	__sgx_epc_page_list_peek(&(lru)->unreclaimable)
 
 struct sgx_epc_page *__sgx_alloc_epc_page(void);
 void sgx_free_epc_page(struct sgx_epc_page *page);
-- 
2.37.3

[PATCH 08/26] x86/sgx: Add EPC page flags to identify type of page

[Kristen Carlson Accardi]

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

Create new flags to help identify whether a page is an enclave page
or a va page and save the page type when the page is recorded.

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/encl.c  |  6 +++---
 arch/x86/kernel/cpu/sgx/ioctl.c |  4 ++--
 arch/x86/kernel/cpu/sgx/main.c  | 21 +++++++++++----------
 arch/x86/kernel/cpu/sgx/sgx.h   |  8 +++++++-
 4 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 4683da9ef4f1..653c9ee5bf57 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -252,7 +252,7 @@ static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl,
 		epc_page = sgx_encl_eldu(&encl->secs, NULL);
 		if (IS_ERR(epc_page))
 			return ERR_CAST(epc_page);
-		sgx_record_epc_page(epc_page, 0);
+		sgx_record_epc_page(epc_page, SGX_EPC_PAGE_ENCLAVE);
 	}
 
 	epc_page = sgx_encl_eldu(entry, encl->secs.epc_page);
@@ -260,7 +260,7 @@ static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl,
 		return ERR_CAST(epc_page);
 
 	encl->secs_child_cnt++;
-	sgx_record_epc_page(entry->epc_page, SGX_EPC_PAGE_RECLAIMER_TRACKED);
+	sgx_record_epc_page(entry->epc_page, SGX_EPC_PAGE_ENCLAVE_RECLAIMABLE);
 
 	return entry;
 }
@@ -1221,7 +1221,7 @@ struct sgx_epc_page *sgx_alloc_va_page(struct sgx_encl *encl, bool reclaim)
 		sgx_encl_free_epc_page(epc_page);
 		return ERR_PTR(-EFAULT);
 	}
-	sgx_record_epc_page(epc_page, 0);
+	sgx_record_epc_page(epc_page, SGX_EPC_PAGE_VERSION_ARRAY);
 
 	return epc_page;
 }
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index aca80a3f38a1..c91cc6a01232 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -114,7 +114,7 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
 	encl->attributes = secs->attributes;
 	encl->attributes_mask = SGX_ATTR_DEBUG | SGX_ATTR_MODE64BIT | SGX_ATTR_KSS;
 
-	sgx_record_epc_page(encl->secs.epc_page, 0);
+	sgx_record_epc_page(encl->secs.epc_page, SGX_EPC_PAGE_ENCLAVE);
 
 	/* Set only after completion, as encl->lock has not been taken. */
 	set_bit(SGX_ENCL_CREATED, &encl->flags);
@@ -325,7 +325,7 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src,
 			goto err_out;
 	}
 
-	sgx_record_epc_page(encl_page->epc_page, SGX_EPC_PAGE_RECLAIMER_TRACKED);
+	sgx_record_epc_page(encl_page->epc_page, SGX_EPC_PAGE_ENCLAVE_RECLAIMABLE);
 	mutex_unlock(&encl->lock);
 	mmap_read_unlock(current->mm);
 	return ret;
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index c76a53b63fa2..09cc83d7cb97 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -304,6 +304,9 @@ static void __sgx_reclaim_pages(void)
 
 		encl_page = epc_page->encl_owner;
 
+		if (WARN_ON_ONCE(!(epc_page->flags & SGX_EPC_PAGE_ENCLAVE)))
+			continue;
+
 		if (kref_get_unless_zero(&encl_page->encl->refcount) != 0) {
 			epc_page->flags |= SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
 			list_move_tail(&epc_page->list, &iso);
@@ -359,8 +362,7 @@ static void __sgx_reclaim_pages(void)
 		sgx_reclaimer_write(epc_page, &backing[i++]);
 
 		kref_put(&encl_page->encl->refcount, sgx_encl_release);
-		epc_page->flags &= ~(SGX_EPC_PAGE_RECLAIMER_TRACKED |
-				     SGX_EPC_PAGE_RECLAIM_IN_PROGRESS);
+		epc_page->flags &= ~SGX_EPC_PAGE_RECLAIM_FLAGS;
 
 		sgx_free_epc_page(epc_page);
 	}
@@ -501,6 +503,7 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
 /**
  * sgx_record_epc_page() - Add a page to the LRU tracking
  * @page:	EPC page
+ * @flags:	Reclaim flags for the page.
  *
  * Mark a page with the specified flags and add it to the appropriate
  * (un)reclaimable list.
@@ -530,18 +533,16 @@ void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
 int sgx_drop_epc_page(struct sgx_epc_page *page)
 {
 	spin_lock(&sgx_global_lru.lock);
-	if (page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED) {
-		/* The page is being reclaimed. */
-		if (page->flags & SGX_EPC_PAGE_RECLAIM_IN_PROGRESS) {
-			spin_unlock(&sgx_global_lru.lock);
-			return -EBUSY;
-		}
-
-		page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
+	if ((page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED) &&
+	    (page->flags & SGX_EPC_PAGE_RECLAIM_IN_PROGRESS)) {
+		spin_unlock(&sgx_global_lru.lock);
+		return -EBUSY;
 	}
 	list_del(&page->list);
 	spin_unlock(&sgx_global_lru.lock);
 
+	page->flags &= ~SGX_EPC_PAGE_RECLAIM_FLAGS;
+
 	return 0;
 }
 
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 29c0981d6310..f3fc027f7cd0 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -32,8 +32,14 @@
 #define SGX_EPC_PAGE_KVM_GUEST		BIT(2)
 /* page flag to indicate reclaim is in progress */
 #define SGX_EPC_PAGE_RECLAIM_IN_PROGRESS BIT(3)
+#define SGX_EPC_PAGE_ENCLAVE		BIT(4)
+#define SGX_EPC_PAGE_VERSION_ARRAY	BIT(5)
+#define SGX_EPC_PAGE_ENCLAVE_RECLAIMABLE (SGX_EPC_PAGE_ENCLAVE | \
+					  SGX_EPC_PAGE_RECLAIMER_TRACKED)
 #define SGX_EPC_PAGE_RECLAIM_FLAGS	(SGX_EPC_PAGE_RECLAIMER_TRACKED | \
-					 SGX_EPC_PAGE_RECLAIM_IN_PROGRESS)
+					 SGX_EPC_PAGE_RECLAIM_IN_PROGRESS | \
+					 SGX_EPC_PAGE_ENCLAVE | \
+					 SGX_EPC_PAGE_VERSION_ARRAY)
 
 struct sgx_epc_page {
 	unsigned int section;
-- 
2.37.3

[PATCH 09/26] x86/sgx: Allow reclaiming up to 32 pages, but scan 16 by default

[Kristen Carlson Accardi]

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

Modify sgx_reclaim_pages() to take a parameter that specifies the
number of pages to scan for reclaiming. Specify a max value of
32, but scan 16 in the usual case. This allows the number of pages
sgx_reclaim_pages() scans to be specified by the caller, and adjusted
in future patches.

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/main.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 09cc83d7cb97..02b9eafa90a2 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -18,6 +18,8 @@
 #include "encl.h"
 #include "encls.h"
 
+#define SGX_MAX_NR_TO_RECLAIM	32
+
 struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS];
 static int sgx_nr_epc_sections;
 static struct task_struct *ksgxd_tsk;
@@ -273,7 +275,10 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
 	mutex_unlock(&encl->lock);
 }
 
-/*
+/**
+ * sgx_reclaim_pages() - Reclaim EPC pages from the consumers
+ * @nr_to_scan:		 Number of EPC pages to scan for 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
  * been accessed since the last scan. Move those pages to the tail of active
@@ -286,9 +291,9 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
  * problematic as it would increase the lock contention too much, which would
  * halt forward progress.
  */
-static void __sgx_reclaim_pages(void)
+static void __sgx_reclaim_pages(int nr_to_scan)
 {
-	struct sgx_backing backing[SGX_NR_TO_SCAN];
+	struct sgx_backing backing[SGX_MAX_NR_TO_RECLAIM];
 	struct sgx_epc_page *epc_page, *tmp;
 	struct sgx_encl_page *encl_page;
 	pgoff_t page_index;
@@ -297,7 +302,7 @@ static void __sgx_reclaim_pages(void)
 	int i;
 
 	spin_lock(&sgx_global_lru.lock);
-	for (i = 0; i < SGX_NR_TO_SCAN; i++) {
+	for (i = 0; i < nr_to_scan; i++) {
 		epc_page = sgx_epc_peek_reclaimable(&sgx_global_lru);
 		if (!epc_page)
 			break;
@@ -327,7 +332,7 @@ static void __sgx_reclaim_pages(void)
 	list_for_each_entry_safe(epc_page, tmp, &iso, list) {
 		encl_page = epc_page->encl_owner;
 
-		if (!sgx_reclaimer_age(epc_page))
+		if (i == SGX_MAX_NR_TO_RECLAIM || !sgx_reclaimer_age(epc_page))
 			goto skip;
 
 		page_index = PFN_DOWN(encl_page->desc - encl_page->encl->base);
@@ -368,9 +373,9 @@ static void __sgx_reclaim_pages(void)
 	}
 }
 
-static void sgx_reclaim_pages(void)
+static void sgx_reclaim_pages(int nr_to_scan)
 {
-	__sgx_reclaim_pages();
+	__sgx_reclaim_pages(nr_to_scan);
 	cond_resched();
 }
 
@@ -390,7 +395,7 @@ static bool sgx_should_reclaim(unsigned long watermark)
 void sgx_reclaim_direct(void)
 {
 	if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
-		__sgx_reclaim_pages();
+		__sgx_reclaim_pages(SGX_NR_TO_SCAN);
 }
 
 static int ksgxd(void *p)
@@ -416,7 +421,7 @@ static int ksgxd(void *p)
 				     sgx_should_reclaim(SGX_NR_HIGH_PAGES));
 
 		if (sgx_should_reclaim(SGX_NR_HIGH_PAGES))
-			sgx_reclaim_pages();
+			sgx_reclaim_pages(SGX_NR_TO_SCAN);
 	}
 
 	return 0;
@@ -591,7 +596,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
 			break;
 		}
 
-		sgx_reclaim_pages();
+		sgx_reclaim_pages(SGX_NR_TO_SCAN);
 	}
 
 	if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
-- 
2.37.3

[PATCH 10/26] x86/sgx: Return the number of EPC pages that were successfully reclaimed

[Kristen Carlson Accardi]

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

Return the number of reclaimed pages from sgx_reclaim_pages(), the EPC
cgroup will use the result to track the success rate of its reclaim
calls, e.g. to escalate to a more forceful reclaiming mode if necessary.

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/main.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 02b9eafa90a2..dfd76c605ef2 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -291,7 +291,7 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
  * problematic as it would increase the lock contention too much, which would
  * halt forward progress.
  */
-static void __sgx_reclaim_pages(int nr_to_scan)
+static int __sgx_reclaim_pages(int nr_to_scan)
 {
 	struct sgx_backing backing[SGX_MAX_NR_TO_RECLAIM];
 	struct sgx_epc_page *epc_page, *tmp;
@@ -326,7 +326,7 @@ static void __sgx_reclaim_pages(int nr_to_scan)
 	spin_unlock(&sgx_global_lru.lock);
 
 	if (list_empty(&iso))
-		return;
+		return 0;
 
 	i = 0;
 	list_for_each_entry_safe(epc_page, tmp, &iso, list) {
@@ -371,12 +371,16 @@ static void __sgx_reclaim_pages(int nr_to_scan)
 
 		sgx_free_epc_page(epc_page);
 	}
+	return i;
 }
 
-static void sgx_reclaim_pages(int nr_to_scan)
+static int sgx_reclaim_pages(int nr_to_scan)
 {
-	__sgx_reclaim_pages(nr_to_scan);
+	int ret;
+
+	ret = __sgx_reclaim_pages(nr_to_scan);
 	cond_resched();
+	return ret;
 }
 
 static bool sgx_should_reclaim(unsigned long watermark)
-- 
2.37.3

[PATCH 11/26] x86/sgx: Add option to ignore age of page during EPC reclaim

[Kristen Carlson Accardi]

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

Add a flag to sgx_reclaim_pages() to instruct it to ignore the age of
page, i.e. reclaim the page even if it's young.  The EPC cgroup will use
the flag to enforce its limits by draining the reclaimable lists before
resorting to other measures, e.g. forcefully reclaimable "unreclaimable"
pages by killing enclaves.

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/main.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index dfd76c605ef2..b72b5868dd01 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -278,6 +278,7 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
 /**
  * sgx_reclaim_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
  *
  * 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
@@ -291,7 +292,7 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
  * problematic as it would increase the lock contention too much, which would
  * halt forward progress.
  */
-static int __sgx_reclaim_pages(int nr_to_scan)
+static int __sgx_reclaim_pages(int nr_to_scan, bool ignore_age)
 {
 	struct sgx_backing backing[SGX_MAX_NR_TO_RECLAIM];
 	struct sgx_epc_page *epc_page, *tmp;
@@ -332,7 +333,8 @@ static int __sgx_reclaim_pages(int nr_to_scan)
 	list_for_each_entry_safe(epc_page, tmp, &iso, list) {
 		encl_page = epc_page->encl_owner;
 
-		if (i == SGX_MAX_NR_TO_RECLAIM || !sgx_reclaimer_age(epc_page))
+		if (i == SGX_MAX_NR_TO_RECLAIM ||
+		    (!ignore_age && !sgx_reclaimer_age(epc_page)))
 			goto skip;
 
 		page_index = PFN_DOWN(encl_page->desc - encl_page->encl->base);
@@ -374,11 +376,11 @@ static int __sgx_reclaim_pages(int nr_to_scan)
 	return i;
 }
 
-static int sgx_reclaim_pages(int nr_to_scan)
+static int sgx_reclaim_pages(int nr_to_scan, bool ignore_age)
 {
 	int ret;
 
-	ret = __sgx_reclaim_pages(nr_to_scan);
+	ret = __sgx_reclaim_pages(nr_to_scan, ignore_age);
 	cond_resched();
 	return ret;
 }
@@ -399,7 +401,7 @@ static bool sgx_should_reclaim(unsigned long watermark)
 void sgx_reclaim_direct(void)
 {
 	if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
-		__sgx_reclaim_pages(SGX_NR_TO_SCAN);
+		__sgx_reclaim_pages(SGX_NR_TO_SCAN, false);
 }
 
 static int ksgxd(void *p)
@@ -425,7 +427,7 @@ static int ksgxd(void *p)
 				     sgx_should_reclaim(SGX_NR_HIGH_PAGES));
 
 		if (sgx_should_reclaim(SGX_NR_HIGH_PAGES))
-			sgx_reclaim_pages(SGX_NR_TO_SCAN);
+			sgx_reclaim_pages(SGX_NR_TO_SCAN, false);
 	}
 
 	return 0;
@@ -600,7 +602,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
 			break;
 		}
 
-		sgx_reclaim_pages(SGX_NR_TO_SCAN);
+		sgx_reclaim_pages(SGX_NR_TO_SCAN, false);
 	}
 
 	if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
-- 
2.37.3

[PATCH 12/26] x86/sgx: Add helper to retrieve SGX EPC LRU given an EPC page

[Kristen Carlson Accardi]

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

Introduce a function that will be used to retrieve an LRU
from an EPC page.

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/main.c | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index b72b5868dd01..c33966eafab6 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -31,6 +31,10 @@ static DEFINE_XARRAY(sgx_epc_address_space);
  * with sgx_global_lru.lock acquired.
  */
 static struct sgx_epc_lru sgx_global_lru;
+static inline struct sgx_epc_lru *sgx_lru(struct sgx_epc_page *epc_page)
+{
+	return &sgx_global_lru;
+}
 
 static atomic_long_t sgx_nr_free_pages = ATOMIC_LONG_INIT(0);
 
@@ -297,6 +301,7 @@ static int __sgx_reclaim_pages(int nr_to_scan, bool ignore_age)
 	struct sgx_backing backing[SGX_MAX_NR_TO_RECLAIM];
 	struct sgx_epc_page *epc_page, *tmp;
 	struct sgx_encl_page *encl_page;
+	struct sgx_epc_lru *lru;
 	pgoff_t page_index;
 	LIST_HEAD(iso);
 	int ret;
@@ -352,10 +357,11 @@ static int __sgx_reclaim_pages(int nr_to_scan, bool ignore_age)
 		continue;
 
 skip:
-		spin_lock(&sgx_global_lru.lock);
+		lru = sgx_lru(epc_page);
+		spin_lock(&lru->lock);
 		epc_page->flags &= ~SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
-		sgx_epc_move_reclaimable(&sgx_global_lru, epc_page);
-		spin_unlock(&sgx_global_lru.lock);
+		sgx_epc_move_reclaimable(lru, epc_page);
+		spin_unlock(&lru->lock);
 
 		kref_put(&encl_page->encl->refcount, sgx_encl_release);
 	}
@@ -521,14 +527,16 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
  */
 void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
 {
-	spin_lock(&sgx_global_lru.lock);
+	struct sgx_epc_lru *lru = sgx_lru(page);
+
+	spin_lock(&lru->lock);
 	WARN_ON(page->flags & SGX_EPC_PAGE_RECLAIM_FLAGS);
 	page->flags |= flags;
 	if (flags & SGX_EPC_PAGE_RECLAIMER_TRACKED)
-		sgx_epc_push_reclaimable(&sgx_global_lru, page);
+		sgx_epc_push_reclaimable(lru, page);
 	else
-		sgx_epc_push_unreclaimable(&sgx_global_lru, page);
-	spin_unlock(&sgx_global_lru.lock);
+		sgx_epc_push_unreclaimable(lru, page);
+	spin_unlock(&lru->lock);
 }
 
 /**
@@ -543,14 +551,16 @@ void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
  */
 int sgx_drop_epc_page(struct sgx_epc_page *page)
 {
-	spin_lock(&sgx_global_lru.lock);
+	struct sgx_epc_lru *lru = sgx_lru(page);
+
+	spin_lock(&lru->lock);
 	if ((page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED) &&
 	    (page->flags & SGX_EPC_PAGE_RECLAIM_IN_PROGRESS)) {
-		spin_unlock(&sgx_global_lru.lock);
+		spin_unlock(&lru->lock);
 		return -EBUSY;
 	}
 	list_del(&page->list);
-	spin_unlock(&sgx_global_lru.lock);
+	spin_unlock(&lru->lock);
 
 	page->flags &= ~SGX_EPC_PAGE_RECLAIM_FLAGS;
 
-- 
2.37.3

[PATCH 13/26] x86/sgx: Prepare for multiple LRUs

[Kristen Carlson Accardi]

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

Add sgx_can_reclaim() wrapper so that in a subsequent patch, multiple LRUs
can be used cleanly.

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/main.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index c33966eafab6..b2c050fcc989 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -391,10 +391,15 @@ static int sgx_reclaim_pages(int nr_to_scan, bool ignore_age)
 	return ret;
 }
 
+static bool sgx_can_reclaim(void)
+{
+	return !list_empty(&sgx_global_lru.reclaimable);
+}
+
 static bool sgx_should_reclaim(unsigned long watermark)
 {
 	return atomic_long_read(&sgx_nr_free_pages) < watermark &&
-	       !list_empty(&sgx_global_lru.reclaimable);
+		sgx_can_reclaim();
 }
 
 /*
@@ -599,7 +604,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
 			break;
 		}
 
-		if (list_empty(&sgx_global_lru.reclaimable))
+		if (!sgx_can_reclaim())
 			return ERR_PTR(-ENOMEM);
 
 		if (!reclaim) {
-- 
2.37.3

[PATCH 14/26] x86/sgx: Expose sgx_reclaim_pages() for use by EPC cgroup

[Kristen Carlson Accardi]

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

Expose the top-level reclaim function as sgx_reclaim_epc_pages() for use
by the upcoming EPC cgroup, which will initiate reclaim to enforce
changes to high/max limits.

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/main.c | 7 ++++---
 arch/x86/kernel/cpu/sgx/sgx.h  | 1 +
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index b2c050fcc989..cb6f57caf24c 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -281,6 +281,7 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
 
 /**
  * sgx_reclaim_pages() - Reclaim EPC pages from the consumers
+ * 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
  *
@@ -382,7 +383,7 @@ static int __sgx_reclaim_pages(int nr_to_scan, bool ignore_age)
 	return i;
 }
 
-static int sgx_reclaim_pages(int nr_to_scan, bool ignore_age)
+int sgx_reclaim_epc_pages(int nr_to_scan, bool ignore_age)
 {
 	int ret;
 
@@ -438,7 +439,7 @@ static int ksgxd(void *p)
 				     sgx_should_reclaim(SGX_NR_HIGH_PAGES));
 
 		if (sgx_should_reclaim(SGX_NR_HIGH_PAGES))
-			sgx_reclaim_pages(SGX_NR_TO_SCAN, false);
+			sgx_reclaim_epc_pages(SGX_NR_TO_SCAN, false);
 	}
 
 	return 0;
@@ -617,7 +618,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
 			break;
 		}
 
-		sgx_reclaim_pages(SGX_NR_TO_SCAN, false);
+		sgx_reclaim_epc_pages(SGX_NR_TO_SCAN, false);
 	}
 
 	if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index f3fc027f7cd0..ca51b3c7d905 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -181,6 +181,7 @@ 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);
 
 void sgx_ipi_cb(void *info);
 
-- 
2.37.3

[PATCH 15/26] x86/sgx: Add helper to grab pages from an arbitrary EPC LRU

[Kristen Carlson Accardi]

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

Move the isolation loop into a standalone helper, sgx_isolate_pages(),
in preparation for existence of multiple LRUs.  Expose the helper to
other SGX code so that it can be called from the EPC cgroup code, e.g.
to isolate pages from a single cgroup LRU.  Exposing the isolation loop
allows the cgroup iteration logic to be wholly encapsulated within the
cgroup code.

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/main.c | 68 +++++++++++++++++++++-------------
 arch/x86/kernel/cpu/sgx/sgx.h  |  2 +
 2 files changed, 44 insertions(+), 26 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index cb6f57caf24c..f8f1451b0a11 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -280,7 +280,46 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
 }
 
 /**
- * sgx_reclaim_pages() - Reclaim EPC pages from the consumers
+ * sgx_isolate_epc_pages() - Isolate pages from an LRU for reclaim
+ * @lru:	LRU from which to reclaim
+ * @nr_to_scan:	Number of pages to scan for reclaim
+ * @dst:	Destination list to hold the isolated pages
+ */
+void sgx_isolate_epc_pages(struct sgx_epc_lru *lru, int *nr_to_scan,
+			   struct list_head *dst)
+{
+	struct sgx_encl_page *encl_page;
+	struct sgx_epc_page *epc_page;
+
+	spin_lock(&lru->lock);
+	for (; *nr_to_scan > 0; --(*nr_to_scan)) {
+		if (list_empty(&lru->reclaimable))
+			break;
+
+		epc_page = sgx_epc_peek_reclaimable(lru);
+		if (!epc_page)
+			break;
+
+		encl_page = epc_page->encl_owner;
+
+		if (WARN_ON_ONCE(!(epc_page->flags & SGX_EPC_PAGE_ENCLAVE)))
+			continue;
+
+		if (kref_get_unless_zero(&encl_page->encl->refcount)) {
+			epc_page->flags |= SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
+			list_move_tail(&epc_page->list, dst);
+		} else {
+			/* The owner is freeing the page, remove it from the
+			 * LRU list
+			 */
+			epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
+			list_del_init(&epc_page->list);
+		}
+	}
+	spin_unlock(&lru->lock);
+}
+
+/**
  * 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
@@ -305,37 +344,14 @@ static int __sgx_reclaim_pages(int nr_to_scan, bool ignore_age)
 	struct sgx_epc_lru *lru;
 	pgoff_t page_index;
 	LIST_HEAD(iso);
+	int i = 0;
 	int ret;
-	int i;
-
-	spin_lock(&sgx_global_lru.lock);
-	for (i = 0; i < nr_to_scan; i++) {
-		epc_page = sgx_epc_peek_reclaimable(&sgx_global_lru);
-		if (!epc_page)
-			break;
-
-		encl_page = epc_page->encl_owner;
 
-		if (WARN_ON_ONCE(!(epc_page->flags & SGX_EPC_PAGE_ENCLAVE)))
-			continue;
-
-		if (kref_get_unless_zero(&encl_page->encl->refcount) != 0) {
-			epc_page->flags |= SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
-			list_move_tail(&epc_page->list, &iso);
-		} else {
-			/* The owner is freeing the page, remove it from the
-			 * LRU list
-			 */
-			epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
-			list_del_init(&epc_page->list);
-		}
-	}
-	spin_unlock(&sgx_global_lru.lock);
+	sgx_isolate_epc_pages(&sgx_global_lru, &nr_to_scan, &iso);
 
 	if (list_empty(&iso))
 		return 0;
 
-	i = 0;
 	list_for_each_entry_safe(epc_page, tmp, &iso, list) {
 		encl_page = epc_page->encl_owner;
 
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index ca51b3c7d905..29c37f20792c 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -182,6 +182,8 @@ 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);
+void sgx_isolate_epc_pages(struct sgx_epc_lru *lru, int *nr_to_scan,
+			   struct list_head *dst);
 
 void sgx_ipi_cb(void *info);
 
-- 
2.37.3

[PATCH 16/26] x86/sgx: Add EPC OOM path to forcefully reclaim EPC

[Kristen Carlson Accardi]

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

Introduce the OOM path for killing an enclave with the reclaimer
is no longer able to reclaim enough EPC pages. Find a victim enclave,
which will be an enclave with EPC pages remaining that are not
accessible to the reclaimer ("unreclaimable"). Once a victim is
identified, mark the enclave as OOM and zap the enclaves entire
page range. Release all the enclaves resources except for the
struct sgx_encl memory itself.

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/encl.c |  74 +++++++++++++++---
 arch/x86/kernel/cpu/sgx/encl.h |   2 +
 arch/x86/kernel/cpu/sgx/main.c | 135 +++++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/sgx/sgx.h  |   1 +
 4 files changed, 201 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 653c9ee5bf57..c1d772a11462 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -622,7 +622,8 @@ static int sgx_vma_access(struct vm_area_struct *vma, unsigned long addr,
 	if (!encl)
 		return -EFAULT;
 
-	if (!test_bit(SGX_ENCL_DEBUG, &encl->flags))
+	if (!test_bit(SGX_ENCL_DEBUG, &encl->flags) ||
+	    test_bit(SGX_ENCL_OOM, &encl->flags))
 		return -EFAULT;
 
 	for (i = 0; i < len; i += cnt) {
@@ -668,16 +669,8 @@ const struct vm_operations_struct sgx_vm_ops = {
 	.access = sgx_vma_access,
 };
 
-/**
- * sgx_encl_release - Destroy an enclave instance
- * @ref:	address of a kref inside &sgx_encl
- *
- * Used together with kref_put(). Frees all the resources associated with the
- * enclave and the instance itself.
- */
-void sgx_encl_release(struct kref *ref)
+static void __sgx_encl_release(struct sgx_encl *encl)
 {
-	struct sgx_encl *encl = container_of(ref, struct sgx_encl, refcount);
 	struct sgx_va_page *va_page;
 	struct sgx_encl_page *entry;
 	unsigned long index;
@@ -712,7 +705,7 @@ void sgx_encl_release(struct kref *ref)
 	while (!list_empty(&encl->va_pages)) {
 		va_page = list_first_entry(&encl->va_pages, struct sgx_va_page,
 					   list);
-		list_del(&va_page->list);
+		list_del_init(&va_page->list);
 		sgx_drop_epc_page(va_page->epc_page);
 		sgx_encl_free_epc_page(va_page->epc_page);
 		kfree(va_page);
@@ -728,10 +721,66 @@ void sgx_encl_release(struct kref *ref)
 	/* Detect EPC page leak's. */
 	WARN_ON_ONCE(encl->secs_child_cnt);
 	WARN_ON_ONCE(encl->secs.epc_page);
+}
+
+/**
+ * sgx_encl_release - Destroy an enclave instance
+ * @ref:	address of a kref inside &sgx_encl
+ *
+ * Used together with kref_put(). Frees all the resources associated with the
+ * enclave and the instance itself.
+ */
+void sgx_encl_release(struct kref *ref)
+{
+	struct sgx_encl *encl = container_of(ref, struct sgx_encl, refcount);
+
+	/* if the enclave was OOM killed previously, it just needs to be freed */
+	if (!test_bit(SGX_ENCL_OOM, &encl->flags))
+		__sgx_encl_release(encl);
 
 	kfree(encl);
 }
 
+/**
+ * sgx_encl_destroy - prepare the enclave for release
+ * @encl:	address of the sgx_encl to drain
+ *
+ * Used during oom kill to empty the mm_list entries after they have
+ * been zapped. Release the remaining enclave resources without freeing
+ * struct sgx_encl.
+ */
+void sgx_encl_destroy(struct sgx_encl *encl)
+{
+	struct sgx_encl_mm *encl_mm;
+
+	for ( ; ; )  {
+		spin_lock(&encl->mm_lock);
+
+		if (list_empty(&encl->mm_list)) {
+			encl_mm = NULL;
+		} else {
+			encl_mm = list_first_entry(&encl->mm_list,
+						   struct sgx_encl_mm, list);
+			list_del_rcu(&encl_mm->list);
+		}
+
+		spin_unlock(&encl->mm_lock);
+
+		/* The enclave is no longer mapped by any mm. */
+		if (!encl_mm)
+			break;
+
+		synchronize_srcu(&encl->srcu);
+		mmu_notifier_unregister(&encl_mm->mmu_notifier, encl_mm->mm);
+		kfree(encl_mm);
+
+		/* 'encl_mm' is gone, put encl_mm->encl reference: */
+		kref_put(&encl->refcount, sgx_encl_release);
+	}
+
+	__sgx_encl_release(encl);
+}
+
 /*
  * 'mm' is exiting and no longer needs mmu notifications.
  */
@@ -801,6 +850,9 @@ int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm)
 	struct sgx_encl_mm *encl_mm;
 	int ret;
 
+	if (test_bit(SGX_ENCL_OOM, &encl->flags))
+		return -ENOMEM;
+
 	/*
 	 * Even though a single enclave may be mapped into an mm more than once,
 	 * each 'mm' only appears once on encl->mm_list. This is guaranteed by
diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
index 831d63f80f5a..f4935632e53a 100644
--- a/arch/x86/kernel/cpu/sgx/encl.h
+++ b/arch/x86/kernel/cpu/sgx/encl.h
@@ -39,6 +39,7 @@ enum sgx_encl_flags {
 	SGX_ENCL_DEBUG		= BIT(1),
 	SGX_ENCL_CREATED	= BIT(2),
 	SGX_ENCL_INITIALIZED	= BIT(3),
+	SGX_ENCL_OOM		= BIT(4),
 };
 
 struct sgx_encl_mm {
@@ -125,5 +126,6 @@ struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl,
 					 unsigned long addr);
 struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl, bool reclaim);
 void sgx_encl_shrink(struct sgx_encl *encl, struct sgx_va_page *va_page);
+void sgx_encl_destroy(struct sgx_encl *encl);
 
 #endif /* _X86_ENCL_H */
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index f8f1451b0a11..5a511046ad38 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -670,6 +670,141 @@ void sgx_free_epc_page(struct sgx_epc_page *page)
 	atomic_long_inc(&sgx_nr_free_pages);
 }
 
+static bool sgx_oom_get_ref(struct sgx_epc_page *epc_page)
+{
+	struct sgx_encl *encl;
+
+	if (epc_page->flags & SGX_EPC_PAGE_ENCLAVE)
+		encl = ((struct sgx_encl_page *)epc_page->encl_owner)->encl;
+	else if (epc_page->flags & SGX_EPC_PAGE_VERSION_ARRAY)
+		encl = epc_page->encl;
+	else
+		return false;
+
+	return kref_get_unless_zero(&encl->refcount);
+}
+
+static struct sgx_epc_page *sgx_oom_get_victim(struct sgx_epc_lru *lru)
+{
+	struct sgx_epc_page *epc_page, *tmp;
+
+	if (list_empty(&lru->unreclaimable))
+		return NULL;
+
+	list_for_each_entry_safe(epc_page, tmp, &lru->unreclaimable, list) {
+		list_del_init(&epc_page->list);
+
+		if (sgx_oom_get_ref(epc_page))
+			return epc_page;
+	}
+	return NULL;
+}
+
+static void sgx_epc_oom_zap(void *owner, struct mm_struct *mm, unsigned long start,
+			    unsigned long end, const struct vm_operations_struct *ops)
+{
+	struct vm_area_struct *vma, *tmp;
+	unsigned long vm_end;
+
+	vma = find_vma(mm, start);
+	if (!vma || vma->vm_ops != ops || vma->vm_private_data != owner ||
+	    vma->vm_start >= end)
+		return;
+
+	for (tmp = vma; tmp->vm_start < end; tmp = tmp->vm_next) {
+		do {
+			vm_end = tmp->vm_end;
+			tmp = tmp->vm_next;
+		} while (tmp && tmp->vm_ops == ops &&
+			 vma->vm_private_data == owner && tmp->vm_start < end);
+
+		zap_page_range(vma, vma->vm_start, vm_end - vma->vm_start);
+
+		if (!tmp)
+			break;
+	}
+}
+
+static void sgx_oom_encl(struct sgx_encl *encl)
+{
+	unsigned long mm_list_version;
+	struct sgx_encl_mm *encl_mm;
+	int idx;
+
+	set_bit(SGX_ENCL_OOM, &encl->flags);
+
+	if (!test_bit(SGX_ENCL_CREATED, &encl->flags))
+		goto out;
+
+	do {
+		mm_list_version = encl->mm_list_version;
+
+		/* Pairs with smp_rmb() in sgx_encl_mm_add(). */
+		smp_rmb();
+
+		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;
+
+			mmap_read_lock(encl_mm->mm);
+
+			sgx_epc_oom_zap(encl, encl_mm->mm, encl->base,
+					encl->base + encl->size, &sgx_vm_ops);
+
+			mmap_read_unlock(encl_mm->mm);
+
+			mmput_async(encl_mm->mm);
+		}
+
+		srcu_read_unlock(&encl->srcu, idx);
+	} while (WARN_ON_ONCE(encl->mm_list_version != mm_list_version));
+
+	mutex_lock(&encl->lock);
+	sgx_encl_destroy(encl);
+	mutex_unlock(&encl->lock);
+
+out:
+	/*
+	 * This puts the refcount we took when we identified this enclave as
+	 * an OOM victim.
+	 */
+	kref_put(&encl->refcount, sgx_encl_release);
+}
+
+static inline void sgx_oom_encl_page(struct sgx_encl_page *encl_page)
+{
+	return sgx_oom_encl(encl_page->encl);
+}
+
+/**
+ * sgx_epc_oom() - invoke EPC out-of-memory handling on target LRU
+ * @lru:	LRU that is low
+ *
+ * Return:	%true if a victim was found and kicked.
+ */
+bool sgx_epc_oom(struct sgx_epc_lru *lru)
+{
+	struct sgx_epc_page *victim;
+
+	spin_lock(&lru->lock);
+	victim = sgx_oom_get_victim(lru);
+	spin_unlock(&lru->lock);
+
+	if (!victim)
+		return false;
+
+	if (victim->flags & SGX_EPC_PAGE_ENCLAVE)
+		sgx_oom_encl_page(victim->encl_owner);
+	else if (victim->flags & SGX_EPC_PAGE_VERSION_ARRAY)
+		sgx_oom_encl(victim->encl);
+	else
+		WARN_ON_ONCE(1);
+
+	return true;
+}
+
 static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
 					 unsigned long index,
 					 struct sgx_epc_section *section)
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 29c37f20792c..db09a8a0ea6e 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -184,6 +184,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim);
 int sgx_reclaim_epc_pages(int nr_to_scan, bool ignore_age);
 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);
 
 void sgx_ipi_cb(void *info);
 
-- 
2.37.3

[PATCH 17/26] cgroup/misc: Add notifier block list support for css events

[Kristen Carlson Accardi]

Consumers of the misc cgroup controller might need to perform separate actions
in the event of a cgroup alloc, free or release call. In addition,
writes to the max value may also need separate action. Add the ability
to allow code to register for these notifications, and
call the notifier block chain list when appropriate.

This code will be utilized by the SGX driver in a future patch.

Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
---
 include/linux/misc_cgroup.h | 17 ++++++++++++
 kernel/cgroup/misc.c        | 52 +++++++++++++++++++++++++++++++++++--
 2 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
index c238207d1615..8f1b7b6cb81d 100644
--- a/include/linux/misc_cgroup.h
+++ b/include/linux/misc_cgroup.h
@@ -21,6 +21,12 @@ enum misc_res_type {
 	MISC_CG_RES_TYPES
 };
 
+enum misc_cg_events {
+	MISC_CG_ALLOC,		/* a misc_cg was allocated */
+	MISC_CG_FREE,		/* a misc_cg was freed */
+	MISC_CG_RELEASED,	/* a misc_cg is being freed */
+	MISC_CG_CHANGE,		/* the misc_cg max value was changed */
+};
 struct misc_cg;
 
 #ifdef CONFIG_CGROUP_MISC
@@ -59,6 +65,8 @@ int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
 		       unsigned long amount);
 void misc_cg_uncharge(enum misc_res_type type, struct misc_cg *cg,
 		      unsigned long amount);
+int register_misc_cg_notifier(struct notifier_block *nb);
+int unregister_misc_cg_notifier(struct notifier_block *nb);
 
 /**
  * css_misc() - Get misc cgroup from the css.
@@ -132,5 +140,14 @@ static inline void put_misc_cg(struct misc_cg *cg)
 {
 }
 
+static inline int register_misc_cg_notifier(struct notifier_block *nb)
+{
+	return 0;
+}
+
+static inline int unregister_misc_cg_notifier(struct notifier_block *nb)
+{
+	return 0;
+}
 #endif /* CONFIG_CGROUP_MISC */
 #endif /* _MISC_CGROUP_H_ */
diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c
index fe3e8a0eb7ed..1e93e1d20347 100644
--- a/kernel/cgroup/misc.c
+++ b/kernel/cgroup/misc.c
@@ -11,6 +11,7 @@
 #include <linux/errno.h>
 #include <linux/atomic.h>
 #include <linux/slab.h>
+#include <linux/notifier.h>
 #include <linux/misc_cgroup.h>
 
 #define MAX_STR "max"
@@ -39,6 +40,11 @@ static struct misc_cg root_cg;
  */
 static unsigned long misc_res_capacity[MISC_CG_RES_TYPES];
 
+/*
+ * Notifier list for misc_cg cgroup callback events.
+ */
+static BLOCKING_NOTIFIER_HEAD(misc_cg_notify_list);
+
 /**
  * parent_misc() - Get the parent of the passed misc cgroup.
  * @cgroup: cgroup whose parent needs to be fetched.
@@ -278,10 +284,12 @@ static ssize_t misc_cg_max_write(struct kernfs_open_file *of, char *buf,
 
 	cg = css_misc(of_css(of));
 
-	if (READ_ONCE(misc_res_capacity[type]))
+	if (READ_ONCE(misc_res_capacity[type])) {
 		WRITE_ONCE(cg->res[type].max, max);
-	else
+		blocking_notifier_call_chain(&misc_cg_notify_list, MISC_CG_CHANGE, cg);
+	} else {
 		ret = -EINVAL;
+	}
 
 	return ret ? ret : nbytes;
 }
@@ -400,6 +408,7 @@ misc_cg_alloc(struct cgroup_subsys_state *parent_css)
 		WRITE_ONCE(cg->res[i].max, MAX_NUM);
 		atomic_long_set(&cg->res[i].usage, 0);
 	}
+	blocking_notifier_call_chain(&misc_cg_notify_list, MISC_CG_ALLOC, cg);
 
 	return &cg->css;
 }
@@ -412,13 +421,52 @@ misc_cg_alloc(struct cgroup_subsys_state *parent_css)
  */
 static void misc_cg_free(struct cgroup_subsys_state *css)
 {
+	blocking_notifier_call_chain(&misc_cg_notify_list, MISC_CG_FREE, css_misc(css));
 	kfree(css_misc(css));
 }
 
+/**
+ * misc_cg_released() - Release the misc cgroup
+ * @css: cgroup subsys object.
+ *
+ * Call the notifier chain to notify about the event.
+ *
+ * Context: Any context.
+ */
+static void misc_cg_released(struct cgroup_subsys_state *css)
+{
+	blocking_notifier_call_chain(&misc_cg_notify_list, MISC_CG_RELEASED, css_misc(css));
+}
+
 /* Cgroup controller callbacks */
 struct cgroup_subsys misc_cgrp_subsys = {
 	.css_alloc = misc_cg_alloc,
 	.css_free = misc_cg_free,
+	.css_released = misc_cg_released,
 	.legacy_cftypes = misc_cg_files,
 	.dfl_cftypes = misc_cg_files,
 };
+
+/**
+ * register_misc_cg_notifier() - Register for css callback events
+ * @nb: notifier_block to register
+ *
+ * Context: Any context.
+ */
+int register_misc_cg_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&misc_cg_notify_list, nb);
+}
+EXPORT_SYMBOL_GPL(register_misc_cg_notifier);
+
+/**
+ * unregister_misc_cg_notifier() - unregister for css callback events
+ * @nb: notifier_block to unregister
+ *
+ * Context: Any context.
+ */
+int unregister_misc_cg_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&misc_cg_notify_list, nb);
+}
+EXPORT_SYMBOL_GPL(unregister_misc_cg_notifier);
-- 
2.37.3

[PATCH 18/26] cgroup/misc: Expose root_misc

[Kristen Carlson Accardi]

The SGX driver will need to get access to the root misc_cg object
to do iterative walks and also determine if a charge will be
towards the root cgroup or not.

Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
---
 include/linux/misc_cgroup.h | 5 +++++
 kernel/cgroup/misc.c        | 9 +++++++++
 2 files changed, 14 insertions(+)

diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
index 8f1b7b6cb81d..b79c78378f17 100644
--- a/include/linux/misc_cgroup.h
+++ b/include/linux/misc_cgroup.h
@@ -59,6 +59,7 @@ struct misc_cg {
 	struct misc_res res[MISC_CG_RES_TYPES];
 };
 
+struct misc_cg *root_misc(void);
 unsigned long misc_cg_res_total_usage(enum misc_res_type type);
 int misc_cg_set_capacity(enum misc_res_type type, unsigned long capacity);
 int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
@@ -106,6 +107,10 @@ static inline void put_misc_cg(struct misc_cg *cg)
 }
 
 #else /* !CONFIG_CGROUP_MISC */
+static inline struct misc_cg *root_misc(void)
+{
+	return NULL;
+}
 
 static inline unsigned long misc_cg_res_total_usage(enum misc_res_type type)
 {
diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c
index 1e93e1d20347..8aa994d9cd02 100644
--- a/kernel/cgroup/misc.c
+++ b/kernel/cgroup/misc.c
@@ -45,6 +45,15 @@ static unsigned long misc_res_capacity[MISC_CG_RES_TYPES];
  */
 static BLOCKING_NOTIFIER_HEAD(misc_cg_notify_list);
 
+/**
+ * root_misc() - Return the root misc cgroup.
+ */
+struct misc_cg *root_misc(void)
+{
+	return &root_cg;
+}
+EXPORT_SYMBOL_GPL(root_misc);
+
 /**
  * parent_misc() - Get the parent of the passed misc cgroup.
  * @cgroup: cgroup whose parent needs to be fetched.
-- 
2.37.3

[PATCH 19/26] cgroup/misc: Expose parent_misc()

[Kristen Carlson Accardi]

To manage the SGX EPC memory via the misc controller, the SGX
driver will need to be able to iterate over the misc cgroup
hierarchy. Make parent_misc() available for a future patch
that will utilize it.

Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
---
 include/linux/misc_cgroup.h | 6 ++++++
 kernel/cgroup/misc.c        | 3 ++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
index b79c78378f17..d1aeb85f2ed6 100644
--- a/include/linux/misc_cgroup.h
+++ b/include/linux/misc_cgroup.h
@@ -60,6 +60,7 @@ struct misc_cg {
 };
 
 struct misc_cg *root_misc(void);
+struct misc_cg *parent_misc(struct misc_cg *cg);
 unsigned long misc_cg_res_total_usage(enum misc_res_type type);
 int misc_cg_set_capacity(enum misc_res_type type, unsigned long capacity);
 int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
@@ -112,6 +113,11 @@ static inline struct misc_cg *root_misc(void)
 	return NULL;
 }
 
+static inline struct misc_cg *parent_misc(struct misc_cg *cg)
+{
+	return NULL;
+}
+
 static inline unsigned long misc_cg_res_total_usage(enum misc_res_type type)
 {
 	return 0;
diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c
index 8aa994d9cd02..b22a055af9ad 100644
--- a/kernel/cgroup/misc.c
+++ b/kernel/cgroup/misc.c
@@ -63,10 +63,11 @@ EXPORT_SYMBOL_GPL(root_misc);
  * * struct misc_cg* - Parent of the @cgroup.
  * * %NULL - If @cgroup is null or the passed cgroup does not have a parent.
  */
-static struct misc_cg *parent_misc(struct misc_cg *cgroup)
+struct misc_cg *parent_misc(struct misc_cg *cgroup)
 {
 	return cgroup ? css_misc(cgroup->css.parent) : NULL;
 }
+EXPORT_SYMBOL_GPL(parent_misc);
 
 /**
  * valid_type() - Check if @type is valid or not.
-- 
2.37.3

[PATCH 20/26] cgroup/misc: allow users of misc cgroup to read specific cgroup usage

[Kristen Carlson Accardi]

Add a function to return the current usage of the specified cgroup.
The SGX driver will need this information to decide whether to
reclaim EPC pages from a cgroup.

Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
---
 include/linux/misc_cgroup.h |  6 ++++++
 kernel/cgroup/misc.c        | 19 +++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
index d1aeb85f2ed6..a9dd087132dc 100644
--- a/include/linux/misc_cgroup.h
+++ b/include/linux/misc_cgroup.h
@@ -61,6 +61,7 @@ struct misc_cg {
 
 struct misc_cg *root_misc(void);
 struct misc_cg *parent_misc(struct misc_cg *cg);
+unsigned long misc_cg_read(enum misc_res_type type, struct misc_cg *cg);
 unsigned long misc_cg_res_total_usage(enum misc_res_type type);
 int misc_cg_set_capacity(enum misc_res_type type, unsigned long capacity);
 int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
@@ -118,6 +119,11 @@ static inline struct misc_cg *parent_misc(struct misc_cg *cg)
 	return NULL;
 }
 
+static inline unsigned long misc_cg_read(enum misc_res_type type, struct misc_cg *cg)
+{
+	return 0;
+}
+
 static inline unsigned long misc_cg_res_total_usage(enum misc_res_type type)
 {
 	return 0;
diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c
index b22a055af9ad..e2c99fdc1d40 100644
--- a/kernel/cgroup/misc.c
+++ b/kernel/cgroup/misc.c
@@ -213,6 +213,25 @@ void misc_cg_uncharge(enum misc_res_type type, struct misc_cg *cg,
 }
 EXPORT_SYMBOL_GPL(misc_cg_uncharge);
 
+/**
+ * misc_cg_read() - Return the current usage of the misc cgroup res.
+ * @type: Type of the misc res.
+ * @cg: Misc cgroup whose usage will be read
+ *
+ * Context: Any context.
+ * Return:
+ * 	The current total usage of the specified misc cgroup.
+ * 	If an invalid misc_res_type is given, zero will be returned.
+ */
+unsigned long misc_cg_read(enum misc_res_type type, struct misc_cg *cg)
+{
+	if (!(valid_type(type) && cg))
+		return 0;
+
+	return atomic_long_read(&cg->res[type].usage);
+}
+EXPORT_SYMBOL_GPL(misc_cg_read);
+
 /**
  * misc_cg_max_show() - Show the misc cgroup max limit.
  * @sf: Interface file
-- 
2.37.3

[PATCH 21/26] cgroup/misc: allow misc cgroup consumers to read the max value

[Kristen Carlson Accardi]

The SGX driver will need to be able to read the max value per cgroup
to determine how far usage is from max. Add an api to return the
max value of the given cgroup.

Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
---
 include/linux/misc_cgroup.h |  6 ++++++
 kernel/cgroup/misc.c        | 19 +++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
index a9dd087132dc..c00deae4d2df 100644
--- a/include/linux/misc_cgroup.h
+++ b/include/linux/misc_cgroup.h
@@ -62,6 +62,7 @@ struct misc_cg {
 struct misc_cg *root_misc(void);
 struct misc_cg *parent_misc(struct misc_cg *cg);
 unsigned long misc_cg_read(enum misc_res_type type, struct misc_cg *cg);
+unsigned long misc_cg_max(enum misc_res_type type, struct misc_cg *cg);
 unsigned long misc_cg_res_total_usage(enum misc_res_type type);
 int misc_cg_set_capacity(enum misc_res_type type, unsigned long capacity);
 int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
@@ -124,6 +125,11 @@ static inline unsigned long misc_cg_read(enum misc_res_type type, struct misc_cg
 	return 0;
 }
 
+static inline unsigned long misc_cg_max(enum misc_res_type type, struct misc_cg *cg)
+{
+	return 0;
+}
+
 static inline unsigned long misc_cg_res_total_usage(enum misc_res_type type)
 {
 	return 0;
diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c
index e2c99fdc1d40..18d0bec7d609 100644
--- a/kernel/cgroup/misc.c
+++ b/kernel/cgroup/misc.c
@@ -232,6 +232,25 @@ unsigned long misc_cg_read(enum misc_res_type type, struct misc_cg *cg)
 }
 EXPORT_SYMBOL_GPL(misc_cg_read);
 
+/**
+ * misc_cg_max() - Return the max value of the misc cgroup res.
+ * @type: Type of the misc res.
+ * @cg: Misc cgroup whose max will be read
+ *
+ * Context: Any context.
+ * Return:
+ * 	The max value of the specified misc cgroup.
+ * 	If an invalid misc_res_type is given, zero will be returned.
+ */
+unsigned long misc_cg_max(enum misc_res_type type, struct misc_cg *cg)
+{
+	if (!(valid_type(type) && cg))
+		return 0;
+
+	return READ_ONCE(cg->res[type].max);
+}
+EXPORT_SYMBOL_GPL(misc_cg_max);
+
 /**
  * misc_cg_max_show() - Show the misc cgroup max limit.
  * @sf: Interface file
-- 
2.37.3

[PATCH 22/26] cgroup/misc: Add private per cgroup data to struct misc_cg

[Kristen Carlson Accardi]

The SGX driver needs to be able to store additional per cgroup data
specific to SGX along with the misc_cg struct. Add the ability to get
and set this data in struct misc_cg.

Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
---
 include/linux/misc_cgroup.h | 12 ++++++++++++
 kernel/cgroup/misc.c        | 39 +++++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
index c00deae4d2df..7fbf3efb0f62 100644
--- a/include/linux/misc_cgroup.h
+++ b/include/linux/misc_cgroup.h
@@ -43,6 +43,7 @@ struct misc_res {
 	unsigned long max;
 	atomic_long_t usage;
 	atomic_long_t events;
+	void *priv;
 };
 
 /**
@@ -63,6 +64,8 @@ struct misc_cg *root_misc(void);
 struct misc_cg *parent_misc(struct misc_cg *cg);
 unsigned long misc_cg_read(enum misc_res_type type, struct misc_cg *cg);
 unsigned long misc_cg_max(enum misc_res_type type, struct misc_cg *cg);
+void *misc_cg_get_priv(enum misc_res_type type, struct misc_cg *cg);
+void misc_cg_set_priv(enum misc_res_type type, struct misc_cg *cg, void *priv);
 unsigned long misc_cg_res_total_usage(enum misc_res_type type);
 int misc_cg_set_capacity(enum misc_res_type type, unsigned long capacity);
 int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
@@ -130,6 +133,15 @@ static inline unsigned long misc_cg_max(enum misc_res_type type, struct misc_cg
 	return 0;
 }
 
+static void *misc_cg_get_priv(enum misc_res_type type, struct misc_cg *cg)
+{
+	return NULL;
+}
+
+static void misc_cg_set_priv(enum misc_res_type type, struct misc_cg *cg, void *priv)
+{
+}
+
 static inline unsigned long misc_cg_res_total_usage(enum misc_res_type type)
 {
 	return 0;
diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c
index 18d0bec7d609..642879ad136f 100644
--- a/kernel/cgroup/misc.c
+++ b/kernel/cgroup/misc.c
@@ -251,6 +251,45 @@ unsigned long misc_cg_max(enum misc_res_type type, struct misc_cg *cg)
 }
 EXPORT_SYMBOL_GPL(misc_cg_max);
 
+/**
+ * misc_cg_get_priv() - Return the priv value of the misc cgroup res.
+ * @type: Type of the misc res.
+ * @cg: Misc cgroup whose priv will be read
+ *
+ * Context: Any context.
+ * Return:
+ * 	The value of the priv field for the specified misc cgroup.
+ * 	If an invalid misc_res_type is given, NULL will be returned.
+ */
+void *misc_cg_get_priv(enum misc_res_type type, struct misc_cg *cg)
+{
+	if (!(valid_type(type) && cg))
+		return NULL;
+
+	return cg->res[type].priv;
+}
+EXPORT_SYMBOL_GPL(misc_cg_get_priv);
+
+/**
+ * misc_cg_set_priv() - Set the priv value of the misc cgroup res.
+ * @type: Type of the misc res.
+ * @cg: Misc cgroup whose priv will be written
+ * @priv: Value to store in the priv field of the struct misc_cg
+ *
+ * If an invalid misc_res_type is given, the priv data will not be
+ * stored.
+ *
+ * Context: Any context.
+ */
+void misc_cg_set_priv(enum misc_res_type type, struct misc_cg *cg, void *priv)
+{
+	if (!(valid_type(type) && cg))
+		return;
+
+	cg->res[type].priv = priv;
+}
+EXPORT_SYMBOL_GPL(misc_cg_set_priv);
+
 /**
  * misc_cg_max_show() - Show the misc cgroup max limit.
  * @sf: Interface file
-- 
2.37.3

[PATCH 23/26] cgroup/misc: Add tryget functionality for misc controller

[Kristen Carlson Accardi]

Allows caller to do a css_tryget() on a specific misc cgroup.

Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
---
 include/linux/misc_cgroup.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
index 7fbf3efb0f62..cee848205715 100644
--- a/include/linux/misc_cgroup.h
+++ b/include/linux/misc_cgroup.h
@@ -112,6 +112,16 @@ static inline void put_misc_cg(struct misc_cg *cg)
 		css_put(&cg->css);
 }
 
+/*
+ * misc_cg_tryget() - Try to increment this misc cgroup ref count.
+ * @cg - cgroup to get.
+ */
+static inline bool misc_cg_tryget(struct misc_cg *cg)
+{
+	if (cg)
+		return css_tryget(&cg->css);
+	return false;
+}
 #else /* !CONFIG_CGROUP_MISC */
 static inline struct misc_cg *root_misc(void)
 {
@@ -175,6 +185,11 @@ static inline void put_misc_cg(struct misc_cg *cg)
 {
 }
 
+static inline bool misc_cg_tryget(struct misc_cg *cg)
+{
+	return true;
+}
+
 static inline int register_misc_cg_notifier(struct notifier_block *nb)
 {
 	return 0;
-- 
2.37.3

[PATCH 24/26] cgroup/misc: Add SGX EPC resource type

[Kristen Carlson Accardi]

Allow SGX EPC memory to be a valid resource type for the misc
controller.

Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
---
 include/linux/misc_cgroup.h | 4 ++++
 kernel/cgroup/misc.c        | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
index cee848205715..aeaf4acf22af 100644
--- a/include/linux/misc_cgroup.h
+++ b/include/linux/misc_cgroup.h
@@ -17,6 +17,10 @@ enum misc_res_type {
 	MISC_CG_RES_SEV,
 	/* AMD SEV-ES ASIDs resource */
 	MISC_CG_RES_SEV_ES,
+#endif
+#ifdef CONFIG_CGROUP_SGX_EPC
+	/* SGX EPC memory resource */
+	MISC_CG_RES_SGX_EPC,
 #endif
 	MISC_CG_RES_TYPES
 };
diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c
index 642879ad136f..e73a034adca3 100644
--- a/kernel/cgroup/misc.c
+++ b/kernel/cgroup/misc.c
@@ -25,6 +25,10 @@ static const char *const misc_res_name[] = {
 	/* AMD SEV-ES ASIDs resource */
 	"sev_es",
 #endif
+#ifdef CONFIG_CGROUP_SGX_EPC
+	/* Intel SGX EPC memory bytes */
+	"sgx_epc",
+#endif
 };
 
 /* Root misc cgroup */
-- 
2.37.3

[PATCH 25/26] x86/sgx: Add support for misc cgroup controller

[Kristen Carlson Accardi]

Implement support for cgroup control of SGX Enclave Page Cache (EPC)
memory using the misc cgroup controller. EPC memory is independent
from normal system memory, e.g. must be reserved at boot from RAM and
cannot be converted between EPC and normal memory while the system is
running. EPC is managed by the SGX subsystem and is not accounted by
the memory controller.

Much like normal system memory, EPC memory can be overcommitted via
virtual memory techniques and pages can be swapped out of the EPC to
their backing store (normal system memory, e.g. shmem).  The SGX EPC
subsystem is analogous to the memory subsytem and the SGX EPC controller
is in turn analogous to the memory controller; it implements limit and
protection models for EPC memory.

The misc controller provides a mechanism to set a hard limit of EPC
usage via the "sgx_epc" resource in "misc.max". The total EPC memory
available on the system is reported via the "sgx_epc" resource in
"misc.capacity".

This patch was modified from its original version to use the misc cgroup
controller instead of a custom controller.

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/Kconfig                     |  13 +
 arch/x86/kernel/cpu/sgx/Makefile     |   1 +
 arch/x86/kernel/cpu/sgx/epc_cgroup.c | 561 +++++++++++++++++++++++++++
 arch/x86/kernel/cpu/sgx/epc_cgroup.h |  59 +++
 arch/x86/kernel/cpu/sgx/main.c       |  86 +++-
 arch/x86/kernel/cpu/sgx/sgx.h        |   5 +-
 6 files changed, 709 insertions(+), 16 deletions(-)
 create mode 100644 arch/x86/kernel/cpu/sgx/epc_cgroup.c
 create mode 100644 arch/x86/kernel/cpu/sgx/epc_cgroup.h

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f9920f1341c8..0eeae4ebe1c3 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1936,6 +1936,19 @@ config X86_SGX
 
 	  If unsure, say N.
 
+config CGROUP_SGX_EPC
+	bool "Miscellaneous Cgroup Controller for Enclave Page Cache (EPC) for Intel SGX"
+	depends on X86_SGX && CGROUP_MISC
+	help
+	  Provides control over the EPC footprint of tasks in a cgroup via
+	  the Miscellaneous cgroup controller.
+
+	  EPC is a subset of regular memory that is usable only by SGX
+	  enclaves and is very limited in quantity, e.g. less than 1%
+	  of total DRAM.
+
+          Say N if unsure.
+
 config EFI
 	bool "EFI runtime service support"
 	depends on ACPI
diff --git a/arch/x86/kernel/cpu/sgx/Makefile b/arch/x86/kernel/cpu/sgx/Makefile
index 9c1656779b2a..12901a488da7 100644
--- a/arch/x86/kernel/cpu/sgx/Makefile
+++ b/arch/x86/kernel/cpu/sgx/Makefile
@@ -4,3 +4,4 @@ obj-y += \
 	ioctl.o \
 	main.o
 obj-$(CONFIG_X86_SGX_KVM)	+= virt.o
+obj-$(CONFIG_CGROUP_SGX_EPC)	       += epc_cgroup.o
diff --git a/arch/x86/kernel/cpu/sgx/epc_cgroup.c b/arch/x86/kernel/cpu/sgx/epc_cgroup.c
new file mode 100644
index 000000000000..03c0fa42880c
--- /dev/null
+++ b/arch/x86/kernel/cpu/sgx/epc_cgroup.c
@@ -0,0 +1,561 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright(c) 2022 Intel Corporation.
+
+#include <linux/atomic.h>
+#include <linux/kernel.h>
+#include <linux/ratelimit.h>
+#include <linux/sched/signal.h>
+#include <linux/slab.h>
+#include <linux/threads.h>
+
+#include "epc_cgroup.h"
+
+#define SGX_EPC_RECLAIM_MIN_PAGES		16UL
+#define SGX_EPC_RECLAIM_MAX_PAGES		64UL
+#define SGX_EPC_RECLAIM_IGNORE_AGE_THRESHOLD	5
+#define SGX_EPC_RECLAIM_OOM_THRESHOLD		5
+
+static struct workqueue_struct *sgx_epc_cg_wq;
+
+struct sgx_epc_reclaim_control {
+	struct sgx_epc_cgroup *epc_cg;
+	int nr_fails;
+	bool ignore_age;
+};
+
+static inline unsigned long sgx_epc_cgroup_page_counter_read(struct sgx_epc_cgroup *epc_cg)
+{
+	 return misc_cg_read(MISC_CG_RES_SGX_EPC, epc_cg->cg) / PAGE_SIZE;
+}
+
+static inline unsigned long sgx_epc_cgroup_max_pages(struct sgx_epc_cgroup *epc_cg)
+{
+	 return misc_cg_max(MISC_CG_RES_SGX_EPC, epc_cg->cg) / PAGE_SIZE;
+}
+
+static inline struct sgx_epc_cgroup *sgx_epc_cgroup_from_misc_cg(struct misc_cg *cg)
+{
+	return (struct sgx_epc_cgroup *)misc_cg_get_priv(MISC_CG_RES_SGX_EPC, cg);
+}
+
+static inline struct sgx_epc_cgroup *parent_epc_cgroup(struct sgx_epc_cgroup *epc_cg)
+{
+	return sgx_epc_cgroup_from_misc_cg(parent_misc(epc_cg->cg));
+}
+
+static inline bool sgx_epc_cgroup_disabled(void)
+{
+	return !cgroup_subsys_enabled(misc_cgrp_subsys);
+}
+
+/**
+ * sgx_epc_cgroup_iter - iterate over the EPC cgroup hierarchy
+ * @root:		hierarchy root
+ * @prev:		previously returned epc_cg, NULL on first invocation
+ * @reclaim_epoch:	epoch for shared reclaim walks, NULL for full walks
+ *
+ * Return: references to children of the hierarchy below @root, or
+ * @root itself, or %NULL after a full round-trip.
+ *
+ * Caller must pass the return value in @prev on subsequent invocations
+ * for reference counting, or use sgx_epc_cgroup_iter_break() to cancel
+ * a hierarchy walk before the round-trip is complete.
+ */
+static struct sgx_epc_cgroup *sgx_epc_cgroup_iter(struct sgx_epc_cgroup *prev,
+						  struct sgx_epc_cgroup *root,
+						  unsigned long *reclaim_epoch)
+{
+	struct cgroup_subsys_state *css = NULL;
+	struct sgx_epc_cgroup *epc_cg = NULL;
+	struct sgx_epc_cgroup *pos = NULL;
+	bool inc_epoch = false;
+
+	if (sgx_epc_cgroup_disabled())
+		return NULL;
+
+	if (!root)
+		root = sgx_epc_cgroup_from_misc_cg(root_misc());
+
+	if (prev && !reclaim_epoch)
+		pos = prev;
+
+	rcu_read_lock();
+
+start:
+	if (reclaim_epoch) {
+		/*
+		 * Abort the walk if a reclaimer working from the same root has
+		 * started a new walk after this reclaimer has already scanned
+		 * at least one cgroup.
+		 */
+		if (prev && *reclaim_epoch != root->epoch)
+			goto out;
+
+		while (1) {
+			pos = READ_ONCE(root->reclaim_iter);
+			if (!pos || misc_cg_tryget(pos->cg))
+				break;
+
+			/*
+			 * The css is dying, clear the reclaim_iter immediately
+			 * instead of waiting for ->css_released to be called.
+			 * Busy waiting serves no purpose and attempting to wait
+			 * for ->css_released may actually block it from being
+			 * called.
+			 */
+			(void)cmpxchg(&root->reclaim_iter, pos, NULL);
+		}
+	}
+
+	if (pos)
+		css = &pos->cg->css;
+
+	while (!epc_cg) {
+		struct misc_cg *cg;
+
+		css = css_next_descendant_pre(css, &root->cg->css);
+		if (!css) {
+			/*
+			 * Increment the epoch as we've reached the end of the
+			 * tree and the next call to css_next_descendant_pre
+			 * will restart at root.  Do not update root->epoch
+			 * directly as we should only do so if we update the
+			 * reclaim_iter, i.e. a different thread may win the
+			 * race and update the epoch for us.
+			 */
+			inc_epoch = true;
+
+			/*
+			 * Reclaimers share the hierarchy walk, and a new one
+			 * might jump in at the end of the hierarchy.  Restart
+			 * at root so that  we don't return NULL on a thread's
+			 * initial call.
+			 */
+			if (!prev)
+				continue;
+			break;
+		}
+
+		cg = css_misc(css);
+		/*
+		 * Verify the css and acquire a reference.  Don't take an
+		 * extra reference to root as it's either the global root
+		 * or is provided by the caller and so is guaranteed to be
+		 * alive.  Keep walking if this css is dying.
+		 */
+		if (cg != root->cg && !misc_cg_tryget(cg))
+			continue;
+
+		epc_cg = sgx_epc_cgroup_from_misc_cg(cg);
+	}
+
+	if (reclaim_epoch) {
+		/*
+		 * reclaim_iter could have already been updated by a competing
+		 * thread; check that the value hasn't changed since we read
+		 * it to avoid reclaiming from the same cgroup twice.  If the
+		 * value did change, put all of our references and restart the
+		 * entire process, for all intents and purposes we're making a
+		 * new call.
+		 */
+		if (cmpxchg(&root->reclaim_iter, pos, epc_cg) != pos) {
+			if (epc_cg && epc_cg != root)
+				put_misc_cg(epc_cg->cg);
+			if (pos)
+				put_misc_cg(pos->cg);
+			css = NULL;
+			epc_cg = NULL;
+			inc_epoch = false;
+			goto start;
+		}
+
+		if (inc_epoch)
+			root->epoch++;
+		if (!prev)
+			*reclaim_epoch = root->epoch;
+
+		if (pos)
+			put_misc_cg(pos->cg);
+	}
+
+out:
+	rcu_read_unlock();
+	if (prev && prev != root)
+		put_misc_cg(prev->cg);
+
+	return epc_cg;
+}
+
+/**
+ * sgx_epc_cgroup_iter_break - abort a hierarchy walk prematurely
+ * @prev:	last visited cgroup as returned by sgx_epc_cgroup_iter()
+ * @root:	hierarchy root
+ */
+static void sgx_epc_cgroup_iter_break(struct sgx_epc_cgroup *prev,
+				      struct sgx_epc_cgroup *root)
+{
+	if (!root)
+		root = sgx_epc_cgroup_from_misc_cg(root_misc());
+	if (prev && prev != root)
+		put_misc_cg(prev->cg);
+}
+
+/**
+ * sgx_epc_cgroup_lru_empty - check if a cgroup tree has no pages on its lrus
+ * @root:	root of the tree to check
+ *
+ * Return: %true if all cgroups under the specified root have empty LRU lists.
+ * Used to avoid livelocks due to a cgroup having a non-zero charge count but
+ * no pages on its LRUs, e.g. due to a dead enclave waiting to be released or
+ * because all pages in the cgroup are unreclaimable.
+ */
+bool sgx_epc_cgroup_lru_empty(struct sgx_epc_cgroup *root)
+{
+	struct sgx_epc_cgroup *epc_cg;
+
+	for (epc_cg = sgx_epc_cgroup_iter(NULL, root, NULL);
+	     epc_cg;
+	     epc_cg = sgx_epc_cgroup_iter(epc_cg, root, NULL)) {
+		if (!list_empty(&epc_cg->lru.reclaimable)) {
+			sgx_epc_cgroup_iter_break(epc_cg, root);
+			return false;
+		}
+	}
+	return true;
+}
+
+/**
+ * sgx_epc_cgroup_isolate_pages - walk a cgroup tree and separate pages
+ * @root:	root of the tree to start walking
+ * @nr_to_scan: The number of pages that need to be isolated
+ * @dst:	Destination list to hold the isolated pages
+ *
+ * Walk the cgroup tree and isolate the pages in the hierarchy
+ * for reclaiming.
+ */
+void sgx_epc_cgroup_isolate_pages(struct sgx_epc_cgroup *root,
+				  int *nr_to_scan, struct list_head *dst)
+{
+        struct sgx_epc_cgroup *epc_cg;
+        unsigned long epoch;
+
+	if (!*nr_to_scan)
+		return;
+
+        for (epc_cg = sgx_epc_cgroup_iter(NULL, root, &epoch);
+             epc_cg;
+             epc_cg = sgx_epc_cgroup_iter(epc_cg, root, &epoch)) {
+                sgx_isolate_epc_pages(&epc_cg->lru, nr_to_scan, dst);
+                if (!*nr_to_scan) {
+                        sgx_epc_cgroup_iter_break(epc_cg, root);
+                        break;
+                }
+        }
+}
+
+static int sgx_epc_cgroup_reclaim_pages(unsigned long nr_pages,
+					struct sgx_epc_reclaim_control *rc)
+{
+	/*
+	 * Ensure sgx_reclaim_pages is called with a minimum and maximum
+	 * number of pages.  Attempting to reclaim only a few pages will
+	 * often fail and is inefficient, while reclaiming a huge number
+	 * of pages can result in soft lockups due to holding various
+	 * locks for an extended duration.  This also bounds nr_pages so
+	 */
+	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, rc->epc_cg);
+}
+
+static int sgx_epc_cgroup_reclaim_failed(struct sgx_epc_reclaim_control *rc)
+{
+	if (sgx_epc_cgroup_lru_empty(rc->epc_cg))
+		return -ENOMEM;
+
+	++rc->nr_fails;
+	if (rc->nr_fails > SGX_EPC_RECLAIM_IGNORE_AGE_THRESHOLD)
+		rc->ignore_age = true;
+
+	return 0;
+}
+
+static inline
+void sgx_epc_reclaim_control_init(struct sgx_epc_reclaim_control *rc,
+				  struct sgx_epc_cgroup *epc_cg)
+{
+	rc->epc_cg = epc_cg;
+	rc->nr_fails = 0;
+	rc->ignore_age = false;
+}
+
+/*
+ * Scheduled by sgx_epc_cgroup_try_charge() to reclaim pages from the
+ * cgroup when the cgroup is at/near its maximum capacity
+ */
+static void sgx_epc_cgroup_reclaim_work_func(struct work_struct *work)
+{
+	struct sgx_epc_reclaim_control rc;
+	struct sgx_epc_cgroup *epc_cg;
+	unsigned long cur, max;
+
+	epc_cg = container_of(work, struct sgx_epc_cgroup, reclaim_work);
+
+	sgx_epc_reclaim_control_init(&rc, epc_cg);
+
+	for (;;) {
+		max = sgx_epc_cgroup_max_pages(epc_cg);
+
+		/*
+		 * Adjust the limit down by one page, the goal is to free up
+		 * pages for fault allocations, not to simply obey the limit.
+		 * Conditionally decrementing max also means the cur vs. max
+		 * check will correctly handle the case where both are zero.
+		 */
+		if (max)
+			max--;
+
+		/*
+		 * Unless the limit is extremely low, in which case forcing
+		 * reclaim will likely cause thrashing, force the cgroup to
+		 * reclaim at least once if it's operating *near* its maximum
+		 * limit by adjusting @max down by half the min reclaim size.
+		 * This work func is scheduled by sgx_epc_cgroup_try_charge
+		 * when it cannot directly reclaim due to being in an atomic
+		 * context, e.g. EPC allocation in a fault handler.  Waiting
+		 * to reclaim until the cgroup is actually at its limit is less
+		 * performant as it means the faulting task is effectively
+		 * blocked until a worker makes its way through the global work
+		 * queue.
+		 */
+		if (max > SGX_EPC_RECLAIM_MAX_PAGES)
+			max -= (SGX_EPC_RECLAIM_MIN_PAGES/2);
+
+		cur = sgx_epc_cgroup_page_counter_read(epc_cg);
+		if (cur <= max)
+			break;
+
+		if (!sgx_epc_cgroup_reclaim_pages(cur - max, &rc)) {
+			if (sgx_epc_cgroup_reclaim_failed(&rc))
+				break;
+		}
+	}
+}
+
+static int __sgx_epc_cgroup_try_charge(struct sgx_epc_cgroup *epc_cg,
+				       unsigned long nr_pages, bool reclaim)
+{
+	struct sgx_epc_reclaim_control rc;
+	unsigned long cur, max, over;
+	unsigned int nr_empty = 0;
+
+	if (epc_cg == sgx_epc_cgroup_from_misc_cg(root_misc())) {
+		misc_cg_try_charge(MISC_CG_RES_SGX_EPC, epc_cg->cg,
+				   nr_pages * PAGE_SIZE);
+		return 0;
+	}
+
+	sgx_epc_reclaim_control_init(&rc, NULL);
+
+	for (;;) {
+		if (!misc_cg_try_charge(MISC_CG_RES_SGX_EPC, epc_cg->cg,
+					nr_pages * PAGE_SIZE))
+			break;
+
+		rc.epc_cg = epc_cg;
+		max = sgx_epc_cgroup_max_pages(rc.epc_cg);
+		if (nr_pages > max)
+			return -ENOMEM;
+
+		if (signal_pending(current))
+			return -ERESTARTSYS;
+
+		if (!reclaim) {
+			queue_work(sgx_epc_cg_wq, &rc.epc_cg->reclaim_work);
+			return -EBUSY;
+		}
+
+		cur = sgx_epc_cgroup_page_counter_read(rc.epc_cg);
+		over = ((cur + nr_pages) > max) ?
+			(cur + nr_pages) - max : SGX_EPC_RECLAIM_MIN_PAGES;
+
+		if (!sgx_epc_cgroup_reclaim_pages(over, &rc)) {
+			if (sgx_epc_cgroup_reclaim_failed(&rc)) {
+				if (++nr_empty > SGX_EPC_RECLAIM_OOM_THRESHOLD)
+					return -ENOMEM;
+				schedule();
+			}
+		}
+	}
+
+	css_get_many(&epc_cg->cg->css, nr_pages);
+
+	return 0;
+}
+
+
+/**
+ * sgx_epc_cgroup_try_charge - hierarchically try to charge a single EPC page
+ * @mm:			the mm_struct of the process to charge
+ * @reclaim:		whether or not synchronous reclaim is allowed
+ *
+ * Returns EPC cgroup or NULL on success, -errno on failure.
+ */
+struct sgx_epc_cgroup *sgx_epc_cgroup_try_charge(struct mm_struct *mm,
+						 bool reclaim)
+{
+	struct sgx_epc_cgroup *epc_cg;
+	int ret;
+
+	if (sgx_epc_cgroup_disabled())
+		return NULL;
+
+	epc_cg = sgx_epc_cgroup_from_misc_cg(get_current_misc_cg());
+	ret = __sgx_epc_cgroup_try_charge(epc_cg, 1, reclaim);
+	put_misc_cg(epc_cg->cg);
+
+	if (ret)
+		return ERR_PTR(ret);
+
+	return epc_cg;
+}
+
+/**
+ * sgx_epc_cgroup_uncharge - hierarchically uncharge EPC pages
+ * @epc_cg:	the charged epc cgroup
+ */
+void sgx_epc_cgroup_uncharge(struct sgx_epc_cgroup *epc_cg)
+{
+	if (sgx_epc_cgroup_disabled())
+		return;
+
+	misc_cg_uncharge(MISC_CG_RES_SGX_EPC, epc_cg->cg, PAGE_SIZE);
+
+	if (epc_cg->cg != root_misc())
+		put_misc_cg(epc_cg->cg);
+}
+
+static void sgx_epc_cgroup_oom(struct sgx_epc_cgroup *root)
+{
+	struct sgx_epc_cgroup *epc_cg;
+
+	for (epc_cg = sgx_epc_cgroup_iter(NULL, root, NULL);
+	     epc_cg;
+	     epc_cg = sgx_epc_cgroup_iter(epc_cg, root, NULL)) {
+		if (sgx_epc_oom(&epc_cg->lru)) {
+			sgx_epc_cgroup_iter_break(epc_cg, root);
+			return;
+		}
+	}
+}
+
+static void sgx_epc_cgroup_release(struct sgx_epc_cgroup *epc_cg)
+{
+	struct sgx_epc_cgroup *dead_cg = epc_cg;
+
+	while ((epc_cg = parent_epc_cgroup(epc_cg)))
+		cmpxchg(&epc_cg->reclaim_iter, dead_cg, NULL);
+}
+
+static void sgx_epc_cgroup_free(struct sgx_epc_cgroup *epc_cg)
+{
+	cancel_work_sync(&epc_cg->reclaim_work);
+	kfree(epc_cg);
+}
+
+static struct sgx_epc_cgroup *sgx_epc_cgroup_alloc(struct misc_cg *cg)
+{
+	struct sgx_epc_cgroup *epc_cg;
+
+	epc_cg = kzalloc(sizeof(struct sgx_epc_cgroup), GFP_KERNEL);
+	if (!epc_cg)
+		return ERR_PTR(-ENOMEM);
+
+	sgx_lru_init(&epc_cg->lru);
+	INIT_WORK(&epc_cg->reclaim_work, sgx_epc_cgroup_reclaim_work_func);
+	epc_cg->cg = cg;
+	misc_cg_set_priv(MISC_CG_RES_SGX_EPC, cg, epc_cg);
+
+	return epc_cg;
+}
+
+static void sgx_epc_cgroup_max_write(struct sgx_epc_cgroup *epc_cg)
+{
+	struct sgx_epc_reclaim_control rc;
+	unsigned int nr_empty = 0;
+	unsigned long cur, max;
+
+	sgx_epc_reclaim_control_init(&rc, epc_cg);
+
+	max = sgx_epc_cgroup_max_pages(epc_cg);
+
+	for (;;) {
+		cur = sgx_epc_cgroup_page_counter_read(epc_cg);
+		if (cur <= max)
+			break;
+
+		if (signal_pending(current))
+			break;
+
+		if (!sgx_epc_cgroup_reclaim_pages(cur - max, &rc)) {
+			if (sgx_epc_cgroup_reclaim_failed(&rc)) {
+				if (++nr_empty > SGX_EPC_RECLAIM_OOM_THRESHOLD)
+					sgx_epc_cgroup_oom(epc_cg);
+				schedule();
+			}
+		}
+	}
+}
+
+static int sgx_epc_cgroup_callback(struct notifier_block *nb,
+				   unsigned long val, void *data)
+{
+	struct misc_cg *cg = data;
+	struct sgx_epc_cgroup *epc_cg;
+
+	if (val == MISC_CG_ALLOC) {
+		epc_cg = sgx_epc_cgroup_alloc(cg);
+		if (!epc_cg)
+			return NOTIFY_BAD;
+
+		return NOTIFY_OK;
+	}
+
+	epc_cg = sgx_epc_cgroup_from_misc_cg(cg);
+
+	if (val == MISC_CG_FREE) {
+		sgx_epc_cgroup_free(epc_cg);
+		return NOTIFY_OK;
+	} else if (val == MISC_CG_CHANGE) {
+		sgx_epc_cgroup_max_write(epc_cg);
+		return NOTIFY_OK;
+	} else if (val == MISC_CG_RELEASED) {
+		sgx_epc_cgroup_release(epc_cg);
+		return NOTIFY_OK;
+	}
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block sgx_epc_cg_nb = {
+	.notifier_call = sgx_epc_cgroup_callback,
+	.priority = 0,
+};
+
+static int __init sgx_epc_cgroup_init(void)
+{
+	if (!boot_cpu_has(X86_FEATURE_SGX))
+		return 0;
+
+	sgx_epc_cg_wq = alloc_workqueue("sgx_epc_cg_wq",
+					WQ_UNBOUND | WQ_FREEZABLE,
+					WQ_UNBOUND_MAX_ACTIVE);
+	BUG_ON(!sgx_epc_cg_wq);
+
+	sgx_epc_cgroup_alloc(root_misc());
+
+	register_misc_cg_notifier(&sgx_epc_cg_nb);
+
+	return 0;
+}
+subsys_initcall(sgx_epc_cgroup_init);
diff --git a/arch/x86/kernel/cpu/sgx/epc_cgroup.h b/arch/x86/kernel/cpu/sgx/epc_cgroup.h
new file mode 100644
index 000000000000..a8c631ee6fac
--- /dev/null
+++ b/arch/x86/kernel/cpu/sgx/epc_cgroup.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright(c) 2022 Intel Corporation. */
+#ifndef _INTEL_SGX_EPC_CGROUP_H_
+#define _INTEL_SGX_EPC_CGROUP_H_
+
+#include <asm/sgx.h>
+#include <linux/cgroup.h>
+#include <linux/list.h>
+#include <linux/misc_cgroup.h>
+#include <linux/page_counter.h>
+#include <linux/workqueue.h>
+
+#include "sgx.h"
+
+#ifndef CONFIG_CGROUP_SGX_EPC
+#define MISC_CG_RES_SGX_EPC MISC_CG_RES_TYPES
+struct sgx_epc_cgroup;
+
+static inline struct sgx_epc_cgroup *sgx_epc_cgroup_try_charge(struct mm_struct *mm,
+							       bool reclaim)
+{
+	return NULL;
+}
+static inline void sgx_epc_cgroup_uncharge(struct sgx_epc_cgroup *epc_cg) { }
+static inline void sgx_epc_cgroup_isolate_pages(struct sgx_epc_cgroup *root,
+						int *nr_to_scan,
+						struct list_head *dst) { }
+static inline struct sgx_epc_lru *epc_cg_lru(struct sgx_epc_cgroup *epc_cg)
+{
+	return NULL;
+}
+static bool sgx_epc_cgroup_lru_empty(struct sgx_epc_cgroup *root)
+{
+	return true;
+}
+#else
+struct sgx_epc_cgroup {
+	struct misc_cg *cg;
+	struct sgx_epc_lru	lru;
+	struct sgx_epc_cgroup	*reclaim_iter;
+	struct work_struct	reclaim_work;
+	unsigned int		epoch;
+};
+
+struct sgx_epc_cgroup *sgx_epc_cgroup_try_charge(struct mm_struct *mm,
+						 bool reclaim);
+void sgx_epc_cgroup_uncharge(struct sgx_epc_cgroup *epc_cg);
+bool sgx_epc_cgroup_lru_empty(struct sgx_epc_cgroup *root);
+void sgx_epc_cgroup_isolate_pages(struct sgx_epc_cgroup *root,
+				  int *nr_to_scan, struct list_head *dst);
+static inline struct sgx_epc_lru *epc_cg_lru(struct sgx_epc_cgroup *epc_cg)
+{
+	if (epc_cg)
+		return &epc_cg->lru;
+	return NULL;
+}
+#endif
+
+#endif /* _INTEL_SGX_EPC_CGROUP_H_ */
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 5a511046ad38..b9b55068f87f 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -6,6 +6,7 @@
 #include <linux/highmem.h>
 #include <linux/kthread.h>
 #include <linux/miscdevice.h>
+#include <linux/misc_cgroup.h>
 #include <linux/node.h>
 #include <linux/pagemap.h>
 #include <linux/ratelimit.h>
@@ -17,6 +18,7 @@
 #include "driver.h"
 #include "encl.h"
 #include "encls.h"
+#include "epc_cgroup.h"
 
 #define SGX_MAX_NR_TO_RECLAIM	32
 
@@ -33,9 +35,20 @@ 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)
 {
+        if (IS_ENABLED(CONFIG_CGROUP_SGX_EPC))
+		return epc_cg_lru(epc_page->epc_cg);
+
 	return &sgx_global_lru;
 }
 
+static inline bool sgx_can_reclaim(void)
+{
+        if (!IS_ENABLED(CONFIG_CGROUP_SGX_EPC))
+		return !list_empty(&sgx_global_lru.reclaimable);
+
+	return !sgx_epc_cgroup_lru_empty(NULL);
+}
+
 static atomic_long_t sgx_nr_free_pages = ATOMIC_LONG_INIT(0);
 
 /* Nodes with one or more EPC sections. */
@@ -320,9 +333,10 @@ void sgx_isolate_epc_pages(struct sgx_epc_lru *lru, int *nr_to_scan,
 }
 
 /**
- * sgx_reclaim_epc_pages() - Reclaim EPC pages from the consumers
+ * __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 +350,8 @@ void sgx_isolate_epc_pages(struct sgx_epc_lru *lru, int *nr_to_scan,
  * problematic as it would increase the lock contention too much, which would
  * halt forward progress.
  */
-static int __sgx_reclaim_pages(int nr_to_scan, bool ignore_age)
+static 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;
@@ -347,7 +362,15 @@ static int __sgx_reclaim_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);
+
+	sgx_epc_cgroup_isolate_pages(epc_cg, &nr_to_scan, &iso);
 
 	if (list_empty(&iso))
 		return 0;
@@ -394,25 +417,33 @@ static int __sgx_reclaim_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;
 
+		if (epc_page->epc_cg) {
+			sgx_epc_cgroup_uncharge(epc_page->epc_cg);
+			epc_page->epc_cg = NULL;
+		}
+
 		sgx_free_epc_page(epc_page);
 	}
 	return i;
 }
 
-int sgx_reclaim_epc_pages(int nr_to_scan, bool ignore_age)
+/**
+ * sgx_reclaim_epc_pages() - wrapper for __sgx_reclaim_epc_pages which
+ * 			     calls cond_resched() upon completion.
+ * @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
+ */
+int sgx_reclaim_epc_pages(int nr_to_scan, bool ignore_age,
+			  struct sgx_epc_cgroup *epc_cg)
 {
 	int ret;
 
-	ret = __sgx_reclaim_pages(nr_to_scan, ignore_age);
+	ret = __sgx_reclaim_epc_pages(nr_to_scan, ignore_age, epc_cg);
 	cond_resched();
 	return ret;
 }
 
-static bool sgx_can_reclaim(void)
-{
-	return !list_empty(&sgx_global_lru.reclaimable);
-}
-
 static bool sgx_should_reclaim(unsigned long watermark)
 {
 	return atomic_long_read(&sgx_nr_free_pages) < watermark &&
@@ -429,7 +460,7 @@ static bool sgx_should_reclaim(unsigned long watermark)
 void sgx_reclaim_direct(void)
 {
 	if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
-		__sgx_reclaim_pages(SGX_NR_TO_SCAN, false);
+		__sgx_reclaim_epc_pages(SGX_NR_TO_SCAN, false, NULL);
 }
 
 static int ksgxd(void *p)
@@ -455,7 +486,7 @@ 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;
@@ -613,6 +644,11 @@ 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;
+	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);
 
 	for ( ; ; ) {
 		page = __sgx_alloc_epc_page();
@@ -621,8 +657,10 @@ 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);
@@ -634,7 +672,14 @@ 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);
+	}
+
+	if (!IS_ERR(page)) {
+		WARN_ON(page->epc_cg);
+		page->epc_cg = epc_cg;
+	} else {
+		sgx_epc_cgroup_uncharge(epc_cg);
 	}
 
 	if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
@@ -667,6 +712,12 @@ void sgx_free_epc_page(struct sgx_epc_page *page)
 	page->flags = SGX_EPC_PAGE_IS_FREE;
 
 	spin_unlock(&node->lock);
+
+	if (page->epc_cg) {
+		sgx_epc_cgroup_uncharge(page->epc_cg);
+		page->epc_cg = NULL;
+	}
+
 	atomic_long_inc(&sgx_nr_free_pages);
 }
 
@@ -831,6 +882,7 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
 		section->pages[i].flags = 0;
 		section->pages[i].encl_owner = NULL;
 		section->pages[i].poison = 0;
+		section->pages[i].epc_cg = NULL;
 		list_add_tail(&section->pages[i].list, &sgx_dirty_page_list);
 	}
 
@@ -995,6 +1047,7 @@ static void __init arch_update_sysfs_visibility(int nid) {}
 static bool __init sgx_page_cache_init(void)
 {
 	u32 eax, ebx, ecx, edx, type;
+	u64 capacity = 0;
 	u64 pa, size;
 	int nid;
 	int i;
@@ -1045,6 +1098,7 @@ static bool __init sgx_page_cache_init(void)
 
 		sgx_epc_sections[i].node =  &sgx_numa_nodes[nid];
 		sgx_numa_nodes[nid].size += size;
+		capacity += size;
 
 		sgx_nr_epc_sections++;
 	}
@@ -1054,6 +1108,8 @@ static bool __init sgx_page_cache_init(void)
 		return false;
 	}
 
+	misc_cg_set_capacity(MISC_CG_RES_SGX_EPC, capacity);
+
 	return true;
 }
 
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index db09a8a0ea6e..4059dd74b0d4 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -40,6 +40,7 @@
 					 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;
@@ -53,6 +54,7 @@ struct sgx_epc_page {
 		struct sgx_encl *encl;
 	};
 	struct list_head list;
+	struct sgx_epc_cgroup *epc_cg;
 };
 
 /*
@@ -181,7 +183,8 @@ 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

[PATCH 26/26] Docs/x86/sgx: Add description for cgroup support

[Kristen Carlson Accardi]

Add initial documentation of how to regulate the distribution of
SGX Enclave Page Cache (EPC) memory via the Miscellaneous cgroup
controller.

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>
---
 Documentation/x86/sgx.rst | 77 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)

diff --git a/Documentation/x86/sgx.rst b/Documentation/x86/sgx.rst
index 2bcbffacbed5..f6ca5594dcf2 100644
--- a/Documentation/x86/sgx.rst
+++ b/Documentation/x86/sgx.rst
@@ -300,3 +300,80 @@ to expected failures and handle them as follows:
    first call.  It indicates a bug in the kernel or the userspace client
    if any of the second round of ``SGX_IOC_VEPC_REMOVE_ALL`` calls has
    a return code other than 0.
+
+
+Cgroup Support
+==============
+
+The "sgx_epc" resource within the Miscellaneous cgroup controller regulates
+distribution of SGX EPC memory, which is a subset of system RAM that
+is used to provide SGX-enabled applications with protected memory,
+and is otherwise inaccessible, i.e. shows up as reserved in
+/proc/iomem and cannot be read/written outside of an SGX enclave.
+
+Although current systems implement EPC by stealing memory from RAM,
+for all intents and purposes the EPC is independent from normal system
+memory, e.g. must be reserved at boot from RAM and cannot be converted
+between EPC and normal memory while the system is running.  The EPC is
+managed by the SGX subsystem and is not accounted by the memory
+controller.  Note that this is true only for EPC memory itself, i.e.
+normal memory allocations related to SGX and EPC memory, e.g. the
+backing memory for evicted EPC pages, are accounted, limited and
+protected by the memory controller.
+
+Much like normal system memory, EPC memory can be overcommitted via
+virtual memory techniques and pages can be swapped out of the EPC
+to their backing store (normal system memory allocated via shmem).
+The SGX EPC subsystem is analogous to the memory subsytem, and
+it implements limit and protection models for EPC memory.
+
+SGX EPC Interface Files
+-----------------------
+
+For a generic description of the Miscellaneous controller interface
+files, please see Documentation/admin-guide/cgroup-v2.rst
+
+All SGX EPC memory amounts are in bytes unless explicitly stated
+otherwise.  If a value which is not PAGE_SIZE aligned is written,
+the actual value used by the controller will be rounded down to
+the closest PAGE_SIZE multiple.
+
+  misc.capacity
+        A read-only flat-keyed file shown only in the root cgroup.
+        The sgx_epc resource will show the total amount of EPC
+        memory available on the platform.
+
+  misc.current
+        A read-only flat-keyed file shown in the non-root cgroups.
+        The sgx_epc resource will show the current active EPC memory
+        usage of the cgroup and its descendants. EPC pages that are
+        swapped out to backing RAM are not included in the current count.
+
+  misc.max
+        A read-write single value file which exists on non-root
+        cgroups. The sgx_epc resource will show the EPC usage
+        hard limit. The default is "max".
+
+        If a cgroup's EPC usage reaches this limit, EPC allocations,
+        e.g. for page fault handling, will be blocked until EPC can
+        be reclaimed from the cgroup.  If EPC cannot be reclaimed in
+        a timely manner, reclaim will be forced, e.g. by ignoring LRU.
+
+  misc.events
+	A read-write flat-keyed file which exists on non-root cgroups.
+	Writes to the file reset the event counters to zero.  A value
+	change in this file generates a file modified event.
+
+	  max
+		The number of times the cgroup has triggered a reclaim
+		due to its EPC usage approaching (or exceeding) its max
+		EPC boundary.
+
+Migration
+---------
+
+Once an EPC page is charged to a cgroup (during allocation), it
+remains charged to the original cgroup until the page is released
+or reclaimed.  Migrating a process to a different cgroup doesn't
+move the EPC charges that it incurred while in the previous cgroup
+to its new cgroup.
-- 
2.37.3

Re: [PATCH 26/26] Docs/x86/sgx: Add description for cgroup support

[Bagas Sanjaya]

On 11/12/22 01:35, Kristen Carlson Accardi wrote:
> diff --git a/Documentation/x86/sgx.rst b/Documentation/x86/sgx.rst
> index 2bcbffacbed5..f6ca5594dcf2 100644
> --- a/Documentation/x86/sgx.rst
> +++ b/Documentation/x86/sgx.rst
> @@ -300,3 +300,80 @@ to expected failures and handle them as follows:
>     first call.  It indicates a bug in the kernel or the userspace client
>     if any of the second round of ``SGX_IOC_VEPC_REMOVE_ALL`` calls has
>     a return code other than 0.
> +
> +
> +Cgroup Support
> +==============
> +
> +The "sgx_epc" resource within the Miscellaneous cgroup controller regulates
> +distribution of SGX EPC memory, which is a subset of system RAM that
> +is used to provide SGX-enabled applications with protected memory,
> +and is otherwise inaccessible, i.e. shows up as reserved in
> +/proc/iomem and cannot be read/written outside of an SGX enclave.
> +
> +Although current systems implement EPC by stealing memory from RAM,
> +for all intents and purposes the EPC is independent from normal system
> +memory, e.g. must be reserved at boot from RAM and cannot be converted
> +between EPC and normal memory while the system is running.  The EPC is
> +managed by the SGX subsystem and is not accounted by the memory
> +controller.  Note that this is true only for EPC memory itself, i.e.
> +normal memory allocations related to SGX and EPC memory, e.g. the
> +backing memory for evicted EPC pages, are accounted, limited and
> +protected by the memory controller.
> +
> +Much like normal system memory, EPC memory can be overcommitted via
> +virtual memory techniques and pages can be swapped out of the EPC
> +to their backing store (normal system memory allocated via shmem).
> +The SGX EPC subsystem is analogous to the memory subsytem, and
> +it implements limit and protection models for EPC memory.
> +
> +SGX EPC Interface Files
> +-----------------------
> +
> +For a generic description of the Miscellaneous controller interface
> +files, please see Documentation/admin-guide/cgroup-v2.rst
> +
> +All SGX EPC memory amounts are in bytes unless explicitly stated
> +otherwise.  If a value which is not PAGE_SIZE aligned is written,
> +the actual value used by the controller will be rounded down to
> +the closest PAGE_SIZE multiple.
> +
> +  misc.capacity
> +        A read-only flat-keyed file shown only in the root cgroup.
> +        The sgx_epc resource will show the total amount of EPC
> +        memory available on the platform.
> +
> +  misc.current
> +        A read-only flat-keyed file shown in the non-root cgroups.
> +        The sgx_epc resource will show the current active EPC memory
> +        usage of the cgroup and its descendants. EPC pages that are
> +        swapped out to backing RAM are not included in the current count.
> +
> +  misc.max
> +        A read-write single value file which exists on non-root
> +        cgroups. The sgx_epc resource will show the EPC usage
> +        hard limit. The default is "max".
> +
> +        If a cgroup's EPC usage reaches this limit, EPC allocations,
> +        e.g. for page fault handling, will be blocked until EPC can
> +        be reclaimed from the cgroup.  If EPC cannot be reclaimed in
> +        a timely manner, reclaim will be forced, e.g. by ignoring LRU.
> +
> +  misc.events
> +	A read-write flat-keyed file which exists on non-root cgroups.
> +	Writes to the file reset the event counters to zero.  A value
> +	change in this file generates a file modified event.
> +
> +	  max
> +		The number of times the cgroup has triggered a reclaim
> +		due to its EPC usage approaching (or exceeding) its max
> +		EPC boundary.
> +
> +Migration
> +---------
> +
> +Once an EPC page is charged to a cgroup (during allocation), it
> +remains charged to the original cgroup until the page is released
> +or reclaimed.  Migrating a process to a different cgroup doesn't
> +move the EPC charges that it incurred while in the previous cgroup
> +to its new cgroup.

The doc LGTM, thanks.

Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>

-- 
An old man doll... just what I always wanted! - Clara

Re: [PATCH 18/26] cgroup/misc: Expose root_misc

[Tejun Heo]

On Fri, Nov 11, 2022 at 10:35:23AM -0800, Kristen Carlson Accardi wrote:
> diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
> index 8f1b7b6cb81d..b79c78378f17 100644
> --- a/include/linux/misc_cgroup.h
> +++ b/include/linux/misc_cgroup.h
> @@ -59,6 +59,7 @@ struct misc_cg {
>  	struct misc_res res[MISC_CG_RES_TYPES];
>  };
>  
> +struct misc_cg *root_misc(void);

This is too generic a name to expose globally. Can we do sth like
cgrp_misc_root()?

Thanks.

-- 
tejun

Re: [PATCH 19/26] cgroup/misc: Expose parent_misc()

[Tejun Heo]

On Fri, Nov 11, 2022 at 10:35:24AM -0800, Kristen Carlson Accardi wrote:
> To manage the SGX EPC memory via the misc controller, the SGX
> driver will need to be able to iterate over the misc cgroup
> hierarchy. Make parent_misc() available for a future patch
> that will utilize it.

Ditto with naming and maybe it'd be easier to make these simple accessors
inline?

Thanks.

-- 
tejun

Re: [PATCH 20/26] cgroup/misc: allow users of misc cgroup to read specific cgroup usage

[Tejun Heo]

On Fri, Nov 11, 2022 at 10:35:25AM -0800, Kristen Carlson Accardi wrote:
> Add a function to return the current usage of the specified cgroup.
> The SGX driver will need this information to decide whether to
> reclaim EPC pages from a cgroup.

This looks fine to me. It'd probably a good idea to keep all the interface
function names consistent with this.

Thanks.

-- 
tejun

Re: [PATCH 21/26] cgroup/misc: allow misc cgroup consumers to read the max value

[Tejun Heo]

On Fri, Nov 11, 2022 at 10:35:26AM -0800, Kristen Carlson Accardi wrote:
> The SGX driver will need to be able to read the max value per cgroup
> to determine how far usage is from max. Add an api to return the
> max value of the given cgroup.

You can add these helpers in one patch and I wouldn't mind a downstream user
just reading the field directly either.

Thanks.

-- 
tejun

Re: [PATCH 22/26] cgroup/misc: Add private per cgroup data to struct misc_cg

[Tejun Heo]

On Fri, Nov 11, 2022 at 10:35:27AM -0800, Kristen Carlson Accardi wrote:
> +void *misc_cg_get_priv(enum misc_res_type type, struct misc_cg *cg)
> +{
> +	if (!(valid_type(type) && cg))
> +		return NULL;
> +
> +	return cg->res[type].priv;
> +}
> +EXPORT_SYMBOL_GPL(misc_cg_get_priv);

Yeah, just deref it. I'm not sure what all these accessors are contributing.

Thanks.

-- 
tejun

Re: [PATCH 25/26] x86/sgx: Add support for misc cgroup controller

[Tejun Heo]

On Fri, Nov 11, 2022 at 10:35:30AM -0800, Kristen Carlson Accardi wrote:
> Implement support for cgroup control of SGX Enclave Page Cache (EPC)
> memory using the misc cgroup controller. EPC memory is independent
> from normal system memory, e.g. must be reserved at boot from RAM and
> cannot be converted between EPC and normal memory while the system is
> running. EPC is managed by the SGX subsystem and is not accounted by
> the memory controller.
> 
> Much like normal system memory, EPC memory can be overcommitted via
> virtual memory techniques and pages can be swapped out of the EPC to
> their backing store (normal system memory, e.g. shmem).  The SGX EPC
> subsystem is analogous to the memory subsytem and the SGX EPC controller
> is in turn analogous to the memory controller; it implements limit and
> protection models for EPC memory.
> 
> The misc controller provides a mechanism to set a hard limit of EPC
> usage via the "sgx_epc" resource in "misc.max". The total EPC memory
> available on the system is reported via the "sgx_epc" resource in
> "misc.capacity".
> 
> This patch was modified from its original version to use the misc cgroup
> controller instead of a custom controller.
> 
> 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>

This looks fine from cgroup POV.

Thanks.

-- 
tejun

Re: [PATCH 17/26] cgroup/misc: Add notifier block list support for css events

[Tejun Heo]

Hello,

On Fri, Nov 11, 2022 at 10:35:22AM -0800, Kristen Carlson Accardi wrote:
> +/**
> + * register_misc_cg_notifier() - Register for css callback events
> + * @nb: notifier_block to register
> + *
> + * Context: Any context.
> + */
> +int register_misc_cg_notifier(struct notifier_block *nb)
> +{
> +	return blocking_notifier_chain_register(&misc_cg_notify_list, nb);
> +}
> +EXPORT_SYMBOL_GPL(register_misc_cg_notifier);
> +
> +/**
> + * unregister_misc_cg_notifier() - unregister for css callback events
> + * @nb: notifier_block to unregister
> + *
> + * Context: Any context.
> + */
> +int unregister_misc_cg_notifier(struct notifier_block *nb)
> +{
> +	return blocking_notifier_chain_unregister(&misc_cg_notify_list, nb);
> +}
> +EXPORT_SYMBOL_GPL(unregister_misc_cg_notifier);

So, I'm not necessarily against this but wonder whether it'd be more
straightforward to add sth like struct misc_res_ops which contains the
optional callbacks and then have an array of pointers to the structs which
are initialized / registered somehow. What do you think?

Thanks.

-- 
tejun

Re: [PATCH 17/26] cgroup/misc: Add notifier block list support for css events

[Kristen Carlson Accardi]

On Mon, 2022-11-14 at 12:42 -1000, Tejun Heo wrote:
> Hello,
> 
> On Fri, Nov 11, 2022 at 10:35:22AM -0800, Kristen Carlson Accardi
> wrote:
> > +/**
> > + * register_misc_cg_notifier() - Register for css callback events
> > + * @nb: notifier_block to register
> > + *
> > + * Context: Any context.
> > + */
> > +int register_misc_cg_notifier(struct notifier_block *nb)
> > +{
> > +       return
> > blocking_notifier_chain_register(&misc_cg_notify_list, nb);
> > +}
> > +EXPORT_SYMBOL_GPL(register_misc_cg_notifier);
> > +
> > +/**
> > + * unregister_misc_cg_notifier() - unregister for css callback
> > events
> > + * @nb: notifier_block to unregister
> > + *
> > + * Context: Any context.
> > + */
> > +int unregister_misc_cg_notifier(struct notifier_block *nb)
> > +{
> > +       return
> > blocking_notifier_chain_unregister(&misc_cg_notify_list, nb);
> > +}
> > +EXPORT_SYMBOL_GPL(unregister_misc_cg_notifier);
> 
> So, I'm not necessarily against this but wonder whether it'd be more
> straightforward to add sth like struct misc_res_ops which contains
> the
> optional callbacks and then have an array of pointers to the structs
> which
> are initialized / registered somehow. What do you think?
> 
> Thanks.
> 

Makes no difference to me TBH - I believe they will be functionally
equivalent and from a downstream user perspective equally as easy to
use, so whatever you think is easiest for you to maintain.

Re: [PATCH 17/26] cgroup/misc: Add notifier block list support for css events

[Tejun Heo]

Hello,

On Mon, Nov 14, 2022 at 03:10:05PM -0800, Kristen Carlson Accardi wrote:
> Makes no difference to me TBH - I believe they will be functionally
> equivalent and from a downstream user perspective equally as easy to
> use, so whatever you think is easiest for you to maintain.

Yeah, functionally they should be equivalent. Hmm... Let's go with the ops
table so that it's more explicit.

Thanks.

-- 
tejun

Re: [PATCH 17/26] cgroup/misc: Add notifier block list support for css events

[Kristen Carlson Accardi]

On Mon, 2022-11-14 at 13:11 -1000, Tejun Heo wrote:
> Hello,
> 
> On Mon, Nov 14, 2022 at 03:10:05PM -0800, Kristen Carlson Accardi
> wrote:
> > Makes no difference to me TBH - I believe they will be functionally
> > equivalent and from a downstream user perspective equally as easy
> > to
> > use, so whatever you think is easiest for you to maintain.
> 
> Yeah, functionally they should be equivalent. Hmm... Let's go with
> the ops
> table so that it's more explicit.
> 
> Thanks.
> 

OK, in the next version I will make this change, consolidate everything
for the misc controller into 1 or 2 patches as you requested, and also
get rid of the helpers and just access the struct directly. Thanks for
your review.

Kristen

Re: [PATCH 01/26] x86/sgx: Call cond_resched() at the end of sgx_reclaim_pages()

[Jarkko Sakkinen]

On Fri, Nov 11, 2022 at 10:35:06AM -0800, Kristen Carlson Accardi wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
> 
> In order to avoid repetition of cond_resched() in ksgxd() and
> sgx_alloc_epc_page(), move the invocation of post-reclaim cond_resched()
> inside sgx_reclaim_pages(). Except in the case of sgx_reclaim_direct(),
> sgx_reclaim_pages() is always called in a loop and is always followed
> by a call to cond_resched().  This will hold true for the EPC cgroup
> as well, which adds even more calls to sgx_reclaim_pages() and thus
> cond_resched(). Calls to sgx_reclaim_direct() may be performance
> sensitive. Allow sgx_reclaim_direct() to avoid the cond_resched()
> call by moving the original sgx_reclaim_pages() call to
> __sgx_reclaim_pages() and then have sgx_reclaim_pages() become a
> wrapper around that call with a cond_resched().
> 
> 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/main.c | 17 +++++++++++------
>  1 file changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index 160c8dbee0ab..ffce6fc70a1f 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -287,7 +287,7 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
>   * problematic as it would increase the lock contention too much, which would
>   * halt forward progress.
>   */
> -static void sgx_reclaim_pages(void)
> +static void __sgx_reclaim_pages(void)
>  {
>  	struct sgx_epc_page *chunk[SGX_NR_TO_SCAN];
>  	struct sgx_backing backing[SGX_NR_TO_SCAN];
> @@ -369,6 +369,12 @@ static void sgx_reclaim_pages(void)
>  	}
>  }
>  
> +static void sgx_reclaim_pages(void)
> +{
> +	__sgx_reclaim_pages();
> +	cond_resched();
> +}
> +
>  static bool sgx_should_reclaim(unsigned long watermark)
>  {
>  	return atomic_long_read(&sgx_nr_free_pages) < watermark &&
> @@ -378,12 +384,14 @@ static bool sgx_should_reclaim(unsigned long watermark)
>  /*
>   * sgx_reclaim_direct() should be called (without enclave's mutex held)
>   * in locations where SGX memory resources might be low and might be
> - * needed in order to make forward progress.
> + * needed in order to make forward progress. This call to
> + * __sgx_reclaim_pages() avoids the cond_resched() in sgx_reclaim_pages()
> + * to improve performance.
>   */
>  void sgx_reclaim_direct(void)
>  {
>  	if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
> -		sgx_reclaim_pages();
> +		__sgx_reclaim_pages();

Is it a big deal to have "extra" cond_resched?

>  }
>  
>  static int ksgxd(void *p)
> @@ -410,8 +418,6 @@ static int ksgxd(void *p)
>  
>  		if (sgx_should_reclaim(SGX_NR_HIGH_PAGES))
>  			sgx_reclaim_pages();
> -
> -		cond_resched();
>  	}
>  
>  	return 0;
> @@ -582,7 +588,6 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
>  		}
>  
>  		sgx_reclaim_pages();
> -		cond_resched();
>  	}
>  
>  	if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
> -- 
> 2.37.3
> 

BR, Jarkko

Re: [PATCH 02/26] x86/sgx: Store struct sgx_encl when allocating new va pages

[Jarkko Sakkinen]

On Fri, Nov 11, 2022 at 10:35:07AM -0800, Kristen Carlson Accardi wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
> 
> When allocating new va pages, pass the struct sgx_encl of the enclave

"Version Array (VA) pages"

> that is allocating the page. sgx_alloc_epc_page() will store this
> value in the encl_owner field of the struct sgx_epc_page. In a later
> patch, version array pages will be placed in an unreclaimable queue,

"VA pages"

> and then when the cgroup max limit is reached and there are no more
> reclaimable pages and the enclave must be oom killed, all the
> va pages associated with that enclave can be uncharged and freed.

"VA pages"

> 
> 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/encl.c  | 5 +++--
>  arch/x86/kernel/cpu/sgx/encl.h  | 2 +-
>  arch/x86/kernel/cpu/sgx/ioctl.c | 2 +-
>  arch/x86/kernel/cpu/sgx/sgx.h   | 2 ++
>  4 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
> index f40d64206ded..4eaf9d21e71b 100644
> --- a/arch/x86/kernel/cpu/sgx/encl.c
> +++ b/arch/x86/kernel/cpu/sgx/encl.c
> @@ -1193,6 +1193,7 @@ void sgx_zap_enclave_ptes(struct sgx_encl *encl, unsigned long addr)
>  
>  /**
>   * sgx_alloc_va_page() - Allocate a Version Array (VA) page
> + * @encl:    The enclave that this page is allocated to.
>   * @reclaim: Reclaim EPC pages directly if none available. Enclave
>   *           mutex should not be held if this is set.
>   *
> @@ -1202,12 +1203,12 @@ void sgx_zap_enclave_ptes(struct sgx_encl *encl, unsigned long addr)
>   *   a VA page,
>   *   -errno otherwise
>   */
> -struct sgx_epc_page *sgx_alloc_va_page(bool reclaim)
> +struct sgx_epc_page *sgx_alloc_va_page(struct sgx_encl *encl, bool reclaim)
>  {
>  	struct sgx_epc_page *epc_page;
>  	int ret;
>  
> -	epc_page = sgx_alloc_epc_page(NULL, reclaim);
> +	epc_page = sgx_alloc_epc_page(encl, reclaim);
>  	if (IS_ERR(epc_page))
>  		return ERR_CAST(epc_page);
>  
> diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
> index f94ff14c9486..831d63f80f5a 100644
> --- a/arch/x86/kernel/cpu/sgx/encl.h
> +++ b/arch/x86/kernel/cpu/sgx/encl.h
> @@ -116,7 +116,7 @@ struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
>  					  unsigned long offset,
>  					  u64 secinfo_flags);
>  void sgx_zap_enclave_ptes(struct sgx_encl *encl, unsigned long addr);
> -struct sgx_epc_page *sgx_alloc_va_page(bool reclaim);
> +struct sgx_epc_page *sgx_alloc_va_page(struct sgx_encl *encl, bool reclaim);
>  unsigned int sgx_alloc_va_slot(struct sgx_va_page *va_page);
>  void sgx_free_va_slot(struct sgx_va_page *va_page, unsigned int offset);
>  bool sgx_va_page_full(struct sgx_va_page *va_page);
> diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
> index ebe79d60619f..9a1bb3c3211a 100644
> --- a/arch/x86/kernel/cpu/sgx/ioctl.c
> +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
> @@ -30,7 +30,7 @@ struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl, bool reclaim)
>  		if (!va_page)
>  			return ERR_PTR(-ENOMEM);
>  
> -		va_page->epc_page = sgx_alloc_va_page(reclaim);
> +		va_page->epc_page = sgx_alloc_va_page(encl, reclaim);
>  		if (IS_ERR(va_page->epc_page)) {
>  			err = ERR_CAST(va_page->epc_page);
>  			kfree(va_page);
> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
> index d16a8baa28d4..efb10eacd3aa 100644
> --- a/arch/x86/kernel/cpu/sgx/sgx.h
> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> @@ -39,6 +39,8 @@ struct sgx_epc_page {
>  		struct sgx_encl_page *encl_owner;
>  		/* Use when SGX_EPC_PAGE_KVM_GUEST set in ->flags: */
>  		void __user *vepc_vaddr;
> +

Spurious newline.

> +		struct sgx_encl *encl;
>  	};
>  	struct list_head list;
>  };
> -- 
> 2.37.3
> 

BR, Jarkko

Re: [PATCH 03/26] x86/sgx: Add 'struct sgx_epc_lru' to encapsulate lru list(s)

[Jarkko Sakkinen]

On Fri, Nov 11, 2022 at 10:35:08AM -0800, Kristen Carlson Accardi wrote:
> Introduce a data structure to 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@intel.com>
> Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
> Cc: Sean Christopherson <seanjc@google.com>
> ---
>  arch/x86/kernel/cpu/sgx/sgx.h | 45 +++++++++++++++++++++++++++++++++++
>  1 file changed, 45 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
> index efb10eacd3aa..aac7d4feb0fa 100644
> --- a/arch/x86/kernel/cpu/sgx/sgx.h
> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> @@ -91,6 +91,51 @@ static inline void *sgx_get_epc_virt_addr(struct sgx_epc_page *page)
>  	return section->virt_addr + index * PAGE_SIZE;
>  }
>  
> +struct sgx_epc_lru {

It's not an LRU. It's a data structure containing two LRU's.

Please rename and add a descriptive comment.

> +	spinlock_t lock;
> +	struct list_head reclaimable;
> +	struct list_head unreclaimable;
> +};
> +
> +static inline void sgx_lru_init(struct sgx_epc_lru *lru)
> +{
> +	spin_lock_init(&lru->lock);
> +	INIT_LIST_HEAD(&lru->reclaimable);
> +	INIT_LIST_HEAD(&lru->unreclaimable);
> +}
> +
> +/*
> + * Must be called with queue lock acquired
> + */
> +static inline void __sgx_epc_page_list_push(struct list_head *list, struct sgx_epc_page *page)
> +{
> +	list_add_tail(&page->list, list);
> +}
> +
> +/*
> + * Must be called with queue lock acquired
> + */
> +static inline struct sgx_epc_page * __sgx_epc_page_list_pop(struct list_head *list)
> +{
> +	struct sgx_epc_page *epc_page;
> +
> +	if (list_empty(list))
> +		return NULL;
> +
> +	epc_page = list_first_entry(list, struct sgx_epc_page, list);
> +	list_del_init(&epc_page->list);
> +	return epc_page;
> +}
> +
> +#define sgx_epc_pop_reclaimable(lru) \
> +	__sgx_epc_page_list_pop(&(lru)->reclaimable)
> +#define sgx_epc_push_reclaimable(lru, page) \
> +	__sgx_epc_page_list_push(&(lru)->reclaimable, page)
> +#define sgx_epc_pop_unreclaimable(lru) \
> +	__sgx_epc_page_list_pop(&(lru)->unreclaimable)
> +#define sgx_epc_push_unreclaimable(lru, page) \
> +	__sgx_epc_page_list_push(&(lru)->unreclaimable, page)

Is there any reason not to declare these as inline functions?

> +
>  struct sgx_epc_page *__sgx_alloc_epc_page(void);
>  void sgx_free_epc_page(struct sgx_epc_page *page);
>  
> -- 
> 2.37.3
> 

BR, Jarkko

Re: [PATCH 06/26] x86/sgx: Introduce RECLAIM_IN_PROGRESS flag for EPC pages

[Jarkko Sakkinen]

On Fri, Nov 11, 2022 at 10:35:11AM -0800, Kristen Carlson Accardi wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
> 
> Keep track of whether the EPC page is in the middle of being reclaimed
> and do not delete the page off the it's LRU if it has not yet finished

"off the it's LRU" ?

> being reclaimed.

I'm not sure how the description makes the change understandable.

> 
> 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/main.c | 14 +++++++++-----
>  arch/x86/kernel/cpu/sgx/sgx.h  |  4 ++++
>  2 files changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index 3b09433ffd85..8c451071fa91 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -305,13 +305,15 @@ static void __sgx_reclaim_pages(void)
>  
>  		encl_page = epc_page->encl_owner;
>  
> -		if (kref_get_unless_zero(&encl_page->encl->refcount) != 0)
> +		if (kref_get_unless_zero(&encl_page->encl->refcount) != 0) {
> +			epc_page->flags |= SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
>  			chunk[cnt++] = epc_page;
> -		else
> +		} else {
>  			/* The owner is freeing the page. No need to add the
>  			 * page back to the list of reclaimable pages.
>  			 */
>  			epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
> +		}
>  	}
>  	spin_unlock(&sgx_global_lru.lock);
>  
> @@ -337,6 +339,7 @@ static void __sgx_reclaim_pages(void)
>  
>  skip:
>  		spin_lock(&sgx_global_lru.lock);
> +		epc_page->flags &= ~SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
>  		sgx_epc_push_reclaimable(&sgx_global_lru, epc_page);
>  		spin_unlock(&sgx_global_lru.lock);
>  
> @@ -360,7 +363,8 @@ static void __sgx_reclaim_pages(void)
>  		sgx_reclaimer_write(epc_page, &backing[i]);
>  
>  		kref_put(&encl_page->encl->refcount, sgx_encl_release);
> -		epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
> +		epc_page->flags &= ~(SGX_EPC_PAGE_RECLAIMER_TRACKED |
> +				     SGX_EPC_PAGE_RECLAIM_IN_PROGRESS);
>  
>  		sgx_free_epc_page(epc_page);
>  	}
> @@ -508,7 +512,7 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
>  void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
>  {
>  	spin_lock(&sgx_global_lru.lock);
> -	WARN_ON(page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED);
> +	WARN_ON(page->flags & SGX_EPC_PAGE_RECLAIM_FLAGS);

Please, open code SGX_EPC_PAGE_RECLAIM_FLAGS. It only adds unnecassry
need to cross-reference to the header file.

Also, please describe the changes on how state flags are used before
and after this patch to the commit message.

>  	page->flags |= flags;
>  	if (flags & SGX_EPC_PAGE_RECLAIMER_TRACKED)
>  		sgx_epc_push_reclaimable(&sgx_global_lru, page);
> @@ -532,7 +536,7 @@ int sgx_drop_epc_page(struct sgx_epc_page *page)
>  	spin_lock(&sgx_global_lru.lock);
>  	if (page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED) {
>  		/* The page is being reclaimed. */
> -		if (list_empty(&page->list)) {
> +		if (page->flags & SGX_EPC_PAGE_RECLAIM_IN_PROGRESS) {
>  			spin_unlock(&sgx_global_lru.lock);
>  			return -EBUSY;
>  		}
> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
> index 969606615211..04ca644928a8 100644
> --- a/arch/x86/kernel/cpu/sgx/sgx.h
> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> @@ -30,6 +30,10 @@
>  #define SGX_EPC_PAGE_IS_FREE		BIT(1)
>  /* Pages allocated for KVM guest */
>  #define SGX_EPC_PAGE_KVM_GUEST		BIT(2)
> +/* page flag to indicate reclaim is in progress */
> +#define SGX_EPC_PAGE_RECLAIM_IN_PROGRESS BIT(3)
> +#define SGX_EPC_PAGE_RECLAIM_FLAGS	(SGX_EPC_PAGE_RECLAIMER_TRACKED | \
> +					 SGX_EPC_PAGE_RECLAIM_IN_PROGRESS)
>  
>  struct sgx_epc_page {
>  	unsigned int section;
> -- 
> 2.37.3
> 

BR, Jarkko

Re: [PATCH 01/26] x86/sgx: Call cond_resched() at the end of sgx_reclaim_pages()

[Reinette Chatre]

Hi Jarkko,

On 11/15/2022 3:27 PM, Jarkko Sakkinen wrote:
> On Fri, Nov 11, 2022 at 10:35:06AM -0800, Kristen Carlson Accardi wrote:
>> From: Sean Christopherson <sean.j.christopherson@intel.com>
>>
>> In order to avoid repetition of cond_resched() in ksgxd() and
>> sgx_alloc_epc_page(), move the invocation of post-reclaim cond_resched()
>> inside sgx_reclaim_pages(). Except in the case of sgx_reclaim_direct(),
>> sgx_reclaim_pages() is always called in a loop and is always followed
>> by a call to cond_resched().  This will hold true for the EPC cgroup
>> as well, which adds even more calls to sgx_reclaim_pages() and thus
>> cond_resched(). Calls to sgx_reclaim_direct() may be performance
>> sensitive. Allow sgx_reclaim_direct() to avoid the cond_resched()
>> call by moving the original sgx_reclaim_pages() call to
>> __sgx_reclaim_pages() and then have sgx_reclaim_pages() become a
>> wrapper around that call with a cond_resched().
>>
>> 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/main.c | 17 +++++++++++------
>>  1 file changed, 11 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
>> index 160c8dbee0ab..ffce6fc70a1f 100644
>> --- a/arch/x86/kernel/cpu/sgx/main.c
>> +++ b/arch/x86/kernel/cpu/sgx/main.c
>> @@ -287,7 +287,7 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
>>   * problematic as it would increase the lock contention too much, which would
>>   * halt forward progress.
>>   */
>> -static void sgx_reclaim_pages(void)
>> +static void __sgx_reclaim_pages(void)
>>  {
>>  	struct sgx_epc_page *chunk[SGX_NR_TO_SCAN];
>>  	struct sgx_backing backing[SGX_NR_TO_SCAN];
>> @@ -369,6 +369,12 @@ static void sgx_reclaim_pages(void)
>>  	}
>>  }
>>  
>> +static void sgx_reclaim_pages(void)
>> +{
>> +	__sgx_reclaim_pages();
>> +	cond_resched();
>> +}
>> +
>>  static bool sgx_should_reclaim(unsigned long watermark)
>>  {
>>  	return atomic_long_read(&sgx_nr_free_pages) < watermark &&
>> @@ -378,12 +384,14 @@ static bool sgx_should_reclaim(unsigned long watermark)
>>  /*
>>   * sgx_reclaim_direct() should be called (without enclave's mutex held)
>>   * in locations where SGX memory resources might be low and might be
>> - * needed in order to make forward progress.
>> + * needed in order to make forward progress. This call to
>> + * __sgx_reclaim_pages() avoids the cond_resched() in sgx_reclaim_pages()
>> + * to improve performance.
>>   */
>>  void sgx_reclaim_direct(void)
>>  {
>>  	if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
>> -		sgx_reclaim_pages();
>> +		__sgx_reclaim_pages();
> 
> Is it a big deal to have "extra" cond_resched?
> 

sgx_reclaim_direct() is used to ensure that there is enough
SGX memory available to make forward progress within a loop that
may span a large range of pages. sgx_reclaim_direct()
ensures that there is enough memory right before it depends on
that available memory. I think that giving other tasks an opportunity
to run in the middle is risky since these other tasks may end
up consuming the SGX memory that was just freed up and thus increase
likelihood of the operation to fail with user getting an EAGAIN error.
Additionally, in a constrained environment where sgx_reclaim_direct()
is needed to reclaim pages an additional cond_resched() could cause
user visible slow down when operating on a large memory range. 

Reinette