Fixes for PPC64 CPU emulation (#2308)

* Fix setting PPC64 CPU model manually

The default POWER10 1.0 was pointing to the correct place in the array,
but for manually set indices we still need to append the same offset in
order to set the correct CPU.

* Actually set MSR.HV correctly on reset

Without this, PPC64 models with the HV bit do not work.

hreg_store_msr cannot set MSR.HV to 1 even if alter_hv = 1,
it just takes the value from the environment unless alter_hv = 1
*AND* MSR.HV was already set.

    if (!alter_hv || !(env->msr & MSR_HVB)) {
        value &= ~MSR_HVB;
        value |= env->msr & MSR_HVB;
    }

Author: kukrimate

qemu/target/ppc/translate_init.inc.c

@@ -10123,6 +10123,7 @@ static void ppc_cpu_reset(CPUState *dev)
     }
 #endif
 
+    env->msr |= MSR_HVB; // alter_hv only does anything if MSR_HVB is already set
     hreg_store_msr(env, msr, 1);
 
     env->nip = env->hreset_vector | env->excp_prefix;
@@ -11011,11 +11012,12 @@ PowerPCCPU *cpu_ppc_init(struct uc_struct *uc)
     memset(cpu, 0, sizeof(*cpu));
 #ifdef TARGET_PPC64
     if (uc->cpu_model == INT_MAX) {
-        uc->cpu_model = UC_CPU_PPC64_POWER10_V1_0 + UC_CPU_PPC32_7457A_V1_2 + 1; // power10_v1.0
+        uc->cpu_model = UC_CPU_PPC64_POWER10_V1_0; // power10_v1.0
     } else if (uc->cpu_model + UC_CPU_PPC32_7457A_V1_2 + 1 >= ARRAY_SIZE(ppc_cpus)) {
         free(cpu);
         return NULL;
     }
+    uc->cpu_model += UC_CPU_PPC32_7457A_V1_2 + 1; // PPC64 models come after PPC32
 #else
     if (uc->cpu_model == INT_MAX) {
         uc->cpu_model = UC_CPU_PPC32_7457A_V1_2; // 7457a_v1.2