[PATCH 2/5] x86/sgx: Mark PCMD page as dirty when modifying contents

[Tim Gardner]

From: Reinette Chatre <reinette.chatre at intel.com>

BugLink: https://bugs.launchpad.net/bugs/1979541

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 marked as dirty to ensure the modified data is retained.

Cc: stable at vger.kernel.org
Fixes: 08999b2489b4 ("x86/sgx: Free backing memory after faulting the enclave page")
Signed-off-by: Reinette Chatre <reinette.chatre at intel.com>
Signed-off-by: Dave Hansen <dave.hansen at linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko at kernel.org>
Tested-by: Haitao Huang <haitao.huang at intel.com>
Link: https://lkml.kernel.org/r/00cd2ac480db01058d112e347b32599c1a806bc4.1652389823.git.reinette.chatre@intel.com
(cherry picked from commit 2154e1c11b7080aa19f47160bd26b6f39bbd7824)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
 arch/x86/kernel/cpu/sgx/encl.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 398695a20605..5104a428b72c 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -84,6 +84,7 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page,
 	}
 
 	memset(pcmd_page + b.pcmd_offset, 0, sizeof(struct sgx_pcmd));
+	set_page_dirty(b.pcmd);
 
 	/*
 	 * The area for the PCMD in the page was zeroed above.  Check if the
-- 
2.36.1