[PATCH v5 2/9] x86/sgx: Save enclave pointer for VA page

[Cathy Zhang <cathy.zhang@intel.com>]

Tearing down all enclaves is required by SGX SVN update, which
involves running the ENCLS[EREMOVE] instruction on every EPC
page. This (tearing down all enclaves) should be coordinated
with any enclaves that may be in the process of existing and thus
already be running ENCLS[EREMOVE] as part of enclave release.

In support of this coordination, it is required to know which enclave
owns each in-use EPC page. It is already possible to locate the
owning enclave of SECS and regular pages but not for VA pages.

Make the following changes for VA pages' location:
1) Make epc->owner type-agnostic by changing its type to 'void *'. So,
   besides "struct sgx_encl_page", it can have other types, like
   "struct sgx_va_page".
2) Save the enclave pointer for each VA page to support locating its
   owning enclave.

Note: to track 2T EPC memory, this scheme of tracking will use
additional 8M memory.

Signed-off-by: Cathy Zhang <cathy.zhang@intel.com>

---
Changes since v4:
 - Add back the blank line removed unintenitonally in encl.h.
   (Jarkko Sakkinen)

Changes since v3:
 - Squash patch "x86/sgx: Provide VA page non-NULL owner" and
   "x86/sgx: Save enclave pointer for VA page". Update commit log.
   (Suggested by Jarkko Sakkinen)
---
 arch/x86/kernel/cpu/sgx/encl.h  | 3 ++-
 arch/x86/kernel/cpu/sgx/sgx.h   | 2 +-
 arch/x86/kernel/cpu/sgx/encl.c  | 5 +++--
 arch/x86/kernel/cpu/sgx/ioctl.c | 3 ++-
 4 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
index 7311bc40bd1b..52e0a3e52598 100644
--- a/arch/x86/kernel/cpu/sgx/encl.h
+++ b/arch/x86/kernel/cpu/sgx/encl.h
@@ -76,6 +76,7 @@ struct sgx_va_page {
 	struct sgx_epc_page *epc_page;
 	DECLARE_BITMAP(slots, SGX_VA_SLOT_COUNT);
 	struct list_head list;
+	struct sgx_encl *encl;
 };
 
 struct sgx_backing {
@@ -113,7 +114,7 @@ void sgx_encl_put_backing(struct sgx_backing *backing);
 int sgx_encl_test_and_clear_young(struct mm_struct *mm,
 				  struct sgx_encl_page *page);
 
-struct sgx_epc_page *sgx_alloc_va_page(void);
+struct sgx_epc_page *sgx_alloc_va_page(struct sgx_va_page *va_page);
 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/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index d7a1490d90bb..f8ed9deac18b 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -33,7 +33,7 @@ struct sgx_epc_page {
 	unsigned int section;
 	u16 flags;
 	u16 poison;
-	struct sgx_encl_page *owner;
+	void *owner;
 	struct list_head list;
 };
 
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 39f7f5dc09fd..08f39fa03a39 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -888,6 +888,7 @@ int sgx_encl_test_and_clear_young(struct mm_struct *mm,
 
 /**
  * sgx_alloc_va_page() - Allocate a Version Array (VA) page
+ * @va_page:	struct sgx_va_page connected to this VA page
  *
  * Allocate a free EPC page and convert it to a Version Array (VA) page.
  *
@@ -895,12 +896,12 @@ int sgx_encl_test_and_clear_young(struct mm_struct *mm,
  *   a VA page,
  *   -errno otherwise
  */
-struct sgx_epc_page *sgx_alloc_va_page(void)
+struct sgx_epc_page *sgx_alloc_va_page(struct sgx_va_page *va_page)
 {
 	struct sgx_epc_page *epc_page;
 	int ret;
 
-	epc_page = sgx_alloc_epc_page(NULL, true);
+	epc_page = sgx_alloc_epc_page(va_page, true);
 	if (IS_ERR(epc_page))
 		return ERR_CAST(epc_page);
 
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index d62720ed1728..939008c63a84 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -30,7 +30,8 @@ static struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl)
 		if (!va_page)
 			return ERR_PTR(-ENOMEM);
 
-		va_page->epc_page = sgx_alloc_va_page();
+		va_page->encl = encl;
+		va_page->epc_page = sgx_alloc_va_page(va_page);
 		if (IS_ERR(va_page->epc_page)) {
 			err = ERR_CAST(va_page->epc_page);
 			kfree(va_page);
-- 
2.17.1