ARM: hyp-stub: Define a return value for failed stub calls

Define a standard return value to be returned when a hyp stub
call fails.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <cdall@linaro.org>

arch/arm/include/asm/virt.h

@@ -104,4 +104,6 @@ extern char __hyp_text_end[];
 
 #endif /* __ASSEMBLY__ */
 
+#define HVC_STUB_ERR	0xbadca11
+
 #endif /* ! VIRT_H */

arch/arm/kernel/hyp-stub.S

@@ -216,7 +216,7 @@ __hyp_stub_do_trap:
 	bne	1f
 	bx	r1
 
-1:	mov	r0, #-1
+1:	ldr	r0, =HVC_STUB_ERR
 
 __hyp_stub_exit:
 	__ERET