[PATCH V4 04/31] x86/sgx: Add wrapper for SGX2 EAUG function

[Reinette Chatre]

Add a wrapper for the EAUG ENCLS leaf function used to
add a page to an initialized enclave.

EAUG:
1) Stores all properties of the new enclave page in the SGX
   hardware's Enclave Page Cache Map (EPCM).
2) Sets the PENDING bit in the EPCM entry of the enclave page.
   This bit is cleared by the enclave by invoking ENCLU leaf
   function EACCEPT or EACCEPTCOPY.

Access from within the enclave to the new enclave page is not
possible until the PENDING bit is cleared.

Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
---
Changes since V3:
- Add Jarkko's Reviewed-by tag.

Changes since V1:
- Split original patch ("x86/sgx: Add wrappers for SGX2 functions")
  in three to introduce the SGX2 functions separately (Jarkko).
- Rewrite commit message to include how the EPCM within the hardware
  is changed by the SGX2 function as well as any calling
  conditions (Jarkko).

 arch/x86/kernel/cpu/sgx/encls.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/encls.h b/arch/x86/kernel/cpu/sgx/encls.h
index 7a1ecf704ec1..99004b02e2ed 100644
--- a/arch/x86/kernel/cpu/sgx/encls.h
+++ b/arch/x86/kernel/cpu/sgx/encls.h
@@ -227,4 +227,10 @@ static inline int __emodt(struct sgx_secinfo *secinfo, void *addr)
 	return __encls_ret_2(EMODT, secinfo, addr);
 }
 
+/* Zero a page of EPC memory and add it to an initialized enclave. */
+static inline int __eaug(struct sgx_pageinfo *pginfo, void *addr)
+{
+	return __encls_2(EAUG, pginfo, addr);
+}
+
 #endif /* _X86_ENCLS_H */
-- 
2.25.1