[RFC PATCH 2/4] x86/sgx: Set dirty bit after modifying page contents

Reinette Chatre
2022-04-28T20:11:42Z

Recent commit 08999b2489b4 ("x86/sgx: Free backing memory
after faulting the enclave page") expanded __sgx_encl_eldu()
to clear an enclave page's PCMD (Paging Crypto MetaData)
from the PCMD page in the backing store after the enclave
page is restored to the enclave.

Since the PCMD page in the backing store is modified the page
should be set as dirty when releasing the reference to
ensure the modified data is retained.

Fixes: 08999b2489b4 ("x86/sgx: Free backing memory after faulting the enclave page")
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
---
arch/x86/kernel/cpu/sgx/encl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index e5d2661800ac..e03f124ce772 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -98,7 +98,7 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page,
kunmap_atomic(pcmd_page);
kunmap_atomic((void *)(unsigned long)pginfo.contents);

- sgx_encl_put_backing(&b, false);
+ sgx_encl_put_backing(&b, true);

sgx_encl_truncate_backing_page(encl, page_index);

--
2.25.1