feat(rmmd): enable SME for RMM

This patch enables Scalable Matrix Extension (SME) for RMM. RMM will
save/restore required registers that are shared with SVE/FPU register
state so that Realm can use FPU or SVE.

The Relevant RMM support can be found here :
https://github.com/TF-RMM/tf-rmm/commit/0ccd7ae58b00

Signed-off-by: Arunachalam Ganapathy <arunachalam.ganapathy@arm.com>
Change-Id: I3bbdb840e7736dec00b71c85fcec3d5719413ffd
diff --git a/services/std_svc/rmmd/rmmd_main.c b/services/std_svc/rmmd/rmmd_main.c
index a929ea2..b809f56 100644
--- a/services/std_svc/rmmd/rmmd_main.c
+++ b/services/std_svc/rmmd/rmmd_main.c
@@ -30,6 +30,7 @@
 #include <platform_def.h>
 #include <services/rmmd_svc.h>
 #include <smccc_helpers.h>
+#include <lib/extensions/sme.h>
 #include <lib/extensions/sve.h>
 #include "rmmd_initial_context.h"
 #include "rmmd_private.h"
@@ -134,6 +135,16 @@
 	}
 
 	pmuv3_enable(ctx);
+
+	/*
+	 * If SME/SME2 is supported and enabled for NS world, then enables SME
+	 * for Realm world. RMM will save/restore required registers that are
+	 * shared with SVE/FPU so that Realm can use FPU or SVE.
+	 */
+	if (is_feat_sme_supported()) {
+		/* sme_enable() also enables SME2 if supported by hardware */
+		sme_enable(ctx);
+	}
 }
 
 /*******************************************************************************