target/ppc: finalize pre-EBB PMU logic

There are still PMU exclusive bits to handle in fire_PMC_interrupt()
before implementing the EBB support. Let's finalize it now to avoid
dealing with PMU and EBB logic at the same time in the next patches.

fire_PMC_interrupt() will fire an Performance Monitor alert depending on
MMCR0_PMAE. If we are required to freeze the timers (MMCR0_FCECE) we'll
also need to update summaries and delete the existing overflow timers.
In all cases we're going to update the cycle counters.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20220225101140.1054160-3-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

target/ppc/power8-pmu.c

@@ -222,6 +222,20 @@ static void pmu_update_overflow_timers(CPUPPCState *env)
     }
 }
 
+static void pmu_delete_timers(CPUPPCState *env)
+{
+    QEMUTimer *pmc_overflow_timer;
+    int sprn;
+
+    for (sprn = SPR_POWER_PMC1; sprn <= SPR_POWER_PMC6; sprn++) {
+        pmc_overflow_timer = get_cyc_overflow_timer(env, sprn);
+
+        if (pmc_overflow_timer) {
+            timer_del(pmc_overflow_timer);
+        }
+    }
+}
+
 void helper_store_mmcr0(CPUPPCState *env, target_ulong value)
 {
     bool hflags_pmcc0 = (value & MMCR0_PMCC0) != 0;
@@ -271,8 +285,26 @@ static void fire_PMC_interrupt(PowerPCCPU *cpu)
 {
     CPUPPCState *env = &cpu->env;
 
-    if (!(env->spr[SPR_POWER_MMCR0] & MMCR0_EBE)) {
-        return;
+    pmu_update_cycles(env);
+
+    if (env->spr[SPR_POWER_MMCR0] & MMCR0_FCECE) {
+        env->spr[SPR_POWER_MMCR0] &= ~MMCR0_FCECE;
+        env->spr[SPR_POWER_MMCR0] |= MMCR0_FC;
+
+        /* Changing MMCR0_FC requires a new HFLAGS_INSN_CNT calc */
+        pmu_update_summaries(env);
+
+        /*
+         * Delete all pending timers if we need to freeze
+         * the PMC. We'll restart them when the PMC starts
+         * running again.
+         */
+        pmu_delete_timers(env);
+    }
+
+    if (env->spr[SPR_POWER_MMCR0] & MMCR0_PMAE) {
+        env->spr[SPR_POWER_MMCR0] &= ~MMCR0_PMAE;
+        env->spr[SPR_POWER_MMCR0] |= MMCR0_PMAO;
     }
 
     /* PMC interrupt not implemented yet */