x86/sgx: Mark PCMD page as dirty when modifying contents

mainline inclusion
from mainline-v5.19-rc1
commit 2154e1c1
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I59I14
CVE: CVE-2021-33135

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2154e1c11b7080aa19f47160bd26b6f39bbd7824

--------------------------------

Recent commit 08999b24 ("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@vger.kernel.org
Fixes: 08999b24 ("x86/sgx: Free backing memory after faulting the enclave page")
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: NJarkko Sakkinen <jarkko@kernel.org>
Tested-by: NHaitao Huang <haitao.huang@intel.com>
Link: https://lkml.kernel.org/r/00cd2ac480db01058d112e347b32599c1a806bc4.1652389823.git.reinette.chatre@intel.comSigned-off-by: NChen Jiahao <chenjiahao16@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: NZhang Jianhua <chris.zjh@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

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