target/arm: mark SP_EL1 with ARM_CP_EL3_NO_EL2_KEEP

SP_EL1 must be kept when EL3 is present but EL2 is not. Therefore mark
it with ARM_CP_EL3_NO_EL2_KEEP.

Fixes: 696ba3771894 ("target/arm: Handle cpreg registration for missing EL")
Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>

Upstream-Status: Submitted [https://lists.gnu.org/archive/html/qemu-devel/2022-09/msg04515.html]

---
 target/arm/helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: qemu-7.1.0/target/arm/helper.c
===================================================================
--- qemu-7.1.0.orig/target/arm/helper.c
+++ qemu-7.1.0/target/arm/helper.c
@@ -4971,7 +4971,7 @@ static const ARMCPRegInfo v8_cp_reginfo[
       .fieldoffset = offsetof(CPUARMState, sp_el[0]) },
     { .name = "SP_EL1", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 4, .crn = 4, .crm = 1, .opc2 = 0,
-      .access = PL2_RW, .type = ARM_CP_ALIAS,
+      .access = PL2_RW, .type = ARM_CP_ALIAS | ARM_CP_EL3_NO_EL2_KEEP,
       .fieldoffset = offsetof(CPUARMState, sp_el[1]) },
     { .name = "SPSel", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 0, .crn = 4, .crm = 2, .opc2 = 0,