target/arm: Ignore SMCR_EL2.LEN and SVCR_EL2.LEN if EL2 is not enabled

When determining the current vector length, the SMCR_EL2.LEN and
SVCR_EL2.LEN settings should only be considered if EL2 is enabled
(compare the pseudocode CurrentSVL and CurrentNSVL which call
EL2Enabled()).

We were checking against ARM_FEATURE_EL2 rather than calling
arm_is_el2_enabled(), which meant that we would look at
SMCR_EL2/SVCR_EL2 when in Secure EL1 or Secure EL0 even if Secure EL2
was not enabled.

Use the correct check in sve_vqm1_for_el_sm().

Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240722172957.1041231-5-peter.maydell@linaro.org

target/arm/helper.c

@@ -7232,7 +7232,7 @@ uint32_t sve_vqm1_for_el_sm(CPUARMState *env, int el, bool sm)
     if (el <= 1 && !el_is_in_host(env, el)) {
         len = MIN(len, 0xf & (uint32_t)cr[1]);
     }
-    if (el <= 2 && arm_feature(env, ARM_FEATURE_EL2)) {
+    if (el <= 2 && arm_is_el2_enabled(env)) {
         len = MIN(len, 0xf & (uint32_t)cr[2]);
     }
     if (arm_feature(env, ARM_FEATURE_EL3)) {