target/arm/hvf: Really set Generic Timer counter frequency

Setting ARMCPU::gt_cntfrq_hz in hvf_arch_init_vcpu() is
not correct because the timers have already be initialized
with the default frequency.

Set it earlier in the AccelOpsClass::cpu_target_realize()
handler instead, and assert the value is correct when
reaching hvf_arch_init_vcpu().

Fixes: a1477da3dd ("hvf: Add Apple Silicon support")
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
Message-ID: <20251103101034.59039-19-philmd@linaro.org>

target/arm/hvf/hvf.c

@@ -897,6 +897,13 @@ cleanup:
     return ret;
 }
 
+static uint64_t get_cntfrq_el0(void)
+{
+    uint64_t freq_hz = 0;
+    asm volatile("mrs %0, cntfrq_el0" : "=r"(freq_hz));
+    return freq_hz;
+}
+
 int hvf_arch_init_vcpu(CPUState *cpu)
 {
     ARMCPU *arm_cpu = ARM_CPU(cpu);
@@ -908,7 +915,9 @@ int hvf_arch_init_vcpu(CPUState *cpu)
     int i;
 
     env->aarch64 = true;
-    asm volatile("mrs %0, cntfrq_el0" : "=r"(arm_cpu->gt_cntfrq_hz));
+
+    /* system count frequency sanity check */
+    assert(arm_cpu->gt_cntfrq_hz == get_cntfrq_el0());
 
     /* Allocate enough space for our sysreg sync */
     arm_cpu->cpreg_indexes = g_renew(uint64_t, arm_cpu->cpreg_indexes,
@@ -974,6 +983,15 @@ int hvf_arch_init_vcpu(CPUState *cpu)
 
 bool hvf_arch_cpu_realize(CPUState *cs, Error **errp)
 {
+    ARMCPU *cpu = ARM_CPU(cs);
+
+    /*
+     * We must set the counter frequency HVF will be using
+     * early, before arm_cpu_realizefn initializes the timers
+     * with it.
+     */
+    cpu->gt_cntfrq_hz = get_cntfrq_el0();
+
     return true;
 }