hw/arm/boot: fix SVE for EL3 direct kernel boot

When booting a CPU with EL3 using the -kernel flag, set up CPTR_EL3 so
that SVE will not trap to EL3.

Signed-off-by: Rémi Denis-Courmont <remi.denis.courmont@huawei.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20201030151541.11976-1-remi@remlab.net
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/arm/boot.c

@@ -742,6 +742,9 @@ static void do_cpu_reset(void *opaque)
                     if (cpu_isar_feature(aa64_mte, cpu)) {
                         env->cp15.scr_el3 |= SCR_ATA;
                     }
+                    if (cpu_isar_feature(aa64_sve, cpu)) {
+                        env->cp15.cptr_el[3] |= CPTR_EZ;
+                    }
                     /* AArch64 kernels never boot in secure mode */
                     assert(!info->secure_boot);
                     /* This hook is only supported for AArch32 currently: