[PATCH v6 01/10] target/ppc: introduce PMUEventType and PMU overflow timers

[Daniel Henrique Barboza]

This patch starts an IBM Power8+ compatible PMU implementation by adding
the representation of PMU events that we are going to sample,
PMUEventType. This enum represents a Perf event that is being sampled by
a specific counter 'sprn'. Events that aren't available (i.e. no event
was set in MMCR1) will be of type 'PMU_EVENT_INVALID'. Other types added
in this patch are PMU_EVENT_CYCLES and PMU_EVENT_INSTRUCTIONS. More
types will be added later on.

Let's also add the required PMU cycle overflow timers. They will be used
to trigger cycle overflows when cycle events are being sampled. This
timer will call cpu_ppc_pmu_timer_cb(), which in turn calls
fire_PMC_interrupt().  Both functions are stubs that will be implemented
later on when EBB support is added.

Two new helper files are created to host this new logic.
cpu_ppc_pmu_init() will init all overflow timers during CPU init time.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/spapr_cpu_core.c |  6 +++++
 target/ppc/cpu.h        | 15 +++++++++++
 target/ppc/meson.build  |  1 +
 target/ppc/power8-pmu.c | 57 +++++++++++++++++++++++++++++++++++++++++
 target/ppc/power8-pmu.h | 25 ++++++++++++++++++
 5 files changed, 104 insertions(+)
 create mode 100644 target/ppc/power8-pmu.c
 create mode 100644 target/ppc/power8-pmu.h

diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 58e7341cb7..45abffd891 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -20,6 +20,7 @@
 #include "target/ppc/kvm_ppc.h"
 #include "hw/ppc/ppc.h"
 #include "target/ppc/mmu-hash64.h"
+#include "target/ppc/power8-pmu.h"
 #include "sysemu/numa.h"
 #include "sysemu/reset.h"
 #include "sysemu/hw_accel.h"
@@ -266,6 +267,11 @@ static bool spapr_realize_vcpu(PowerPCCPU *cpu, 
SpaprMachineState *spapr,
         return false;
     }
 
+    /* Init PMU interrupt timer (TCG only) */
+    if (!kvm_enabled()) {
+        cpu_ppc_pmu_init(env);
+    }
+
     if (!sc->pre_3_0_migration) {
         vmstate_register(NULL, cs->cpu_index, &vmstate_spapr_cpu_state,
                          cpu->machine_data);
diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index e946da5f3a..04ef9300af 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -296,6 +296,15 @@ typedef struct ppc_v3_pate_t {
     uint64_t dw1;
 } ppc_v3_pate_t;
 
+/* PMU related structs and defines */
+#define PMU_COUNTERS_NUM 6
+#define PMU_TIMERS_NUM   (PMU_COUNTERS_NUM - 1) /* PMC5 doesn't count cycles */
+typedef enum {
+    PMU_EVENT_INVALID = 0,
+    PMU_EVENT_CYCLES,
+    PMU_EVENT_INSTRUCTIONS,
+} PMUEventType;
+
 /*****************************************************************************/
 /* Machine state register bits definition                                    */
 #define MSR_SF   63 /* Sixty-four-bit mode                            hflags */
@@ -1191,6 +1200,12 @@ struct CPUPPCState {
     uint32_t tm_vscr;
     uint64_t tm_dscr;
     uint64_t tm_tar;
+
+    /*
+     * Timers used to fire performance monitor alerts
+     * when counting cycles.
+     */
+    QEMUTimer *pmu_cyc_overflow_timers[PMU_TIMERS_NUM];
 };
 
 #define SET_FIT_PERIOD(a_, b_, c_, d_)          \
diff --git a/target/ppc/meson.build b/target/ppc/meson.build
index b85f295703..a49a8911e0 100644
--- a/target/ppc/meson.build
+++ b/target/ppc/meson.build
@@ -51,6 +51,7 @@ ppc_softmmu_ss.add(when: 'TARGET_PPC64', if_true: files(
   'mmu-book3s-v3.c',
   'mmu-hash64.c',
   'mmu-radix64.c',
+  'power8-pmu.c',
 ))
 
 target_arch += {'ppc': ppc_ss}
diff --git a/target/ppc/power8-pmu.c b/target/ppc/power8-pmu.c
new file mode 100644
index 0000000000..3c2f73896f
--- /dev/null
+++ b/target/ppc/power8-pmu.c
@@ -0,0 +1,57 @@
+/*
+ * PMU emulation helpers for TCG IBM POWER chips
+ *
+ *  Copyright IBM Corp. 2021
+ *
+ * Authors:
+ *  Daniel Henrique Barboza      <danielhb413@gmail.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+
+#include "power8-pmu.h"
+#include "cpu.h"
+#include "helper_regs.h"
+#include "exec/exec-all.h"
+#include "exec/helper-proto.h"
+#include "qemu/error-report.h"
+#include "qemu/main-loop.h"
+#include "hw/ppc/ppc.h"
+
+#if defined(TARGET_PPC64) && !defined(CONFIG_USER_ONLY)
+
+static void fire_PMC_interrupt(PowerPCCPU *cpu)
+{
+    CPUPPCState *env = &cpu->env;
+
+    if (!(env->spr[SPR_POWER_MMCR0] & MMCR0_EBE)) {
+        return;
+    }
+
+    /* PMC interrupt not implemented yet */
+    return;
+}
+
+static void cpu_ppc_pmu_timer_cb(void *opaque)
+{
+    PowerPCCPU *cpu = opaque;
+
+    fire_PMC_interrupt(cpu);
+}
+
+void cpu_ppc_pmu_init(CPUPPCState *env)
+{
+    PowerPCCPU *cpu = env_archcpu(env);
+    int i;
+
+    for (i = 0; i < PMU_TIMERS_NUM; i++) {
+        env->pmu_cyc_overflow_timers[i] = timer_new_ns(QEMU_CLOCK_VIRTUAL,
+                                                       &cpu_ppc_pmu_timer_cb,
+                                                       cpu);
+    }
+}
+
+#endif /* defined(TARGET_PPC64) && !defined(CONFIG_USER_ONLY) */
diff --git a/target/ppc/power8-pmu.h b/target/ppc/power8-pmu.h
new file mode 100644
index 0000000000..49a813a443
--- /dev/null
+++ b/target/ppc/power8-pmu.h
@@ -0,0 +1,25 @@
+/*
+ * PMU emulation helpers for TCG IBM POWER chips
+ *
+ *  Copyright IBM Corp. 2021
+ *
+ * Authors:
+ *  Daniel Henrique Barboza      <danielhb413@gmail.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef POWER8_PMU
+#define POWER8_PMU
+
+#include "qemu/osdep.h"
+#include "cpu.h"
+#include "exec/exec-all.h"
+#include "exec/helper-proto.h"
+#include "qemu/error-report.h"
+#include "qemu/main-loop.h"
+
+void cpu_ppc_pmu_init(CPUPPCState *env);
+
+#endif
-- 
2.31.1