target/ppc/power8-pmu.c: add PM_RUN_INST_CMPL (0xFA) event

PM_RUN_INST_CMPL, instructions completed with the run latch set, is
the architected PowerISA v3.1 event defined with PMC4SEL = 0xFA.

Implement it by checking for the CTRL RUN bit before incrementing the
counter. To make this work properly we also need to force a new
translation block each time SPR_CTRL is written. A small tweak in
pmu_increment_insns() is then needed to only increment this event
if the thread has the run latch.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20211201151734.654994-8-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

target/ppc/cpu.h

@@ -303,6 +303,7 @@ typedef enum {
     PMU_EVENT_INACTIVE,
     PMU_EVENT_CYCLES,
     PMU_EVENT_INSTRUCTIONS,
+    PMU_EVENT_INSN_RUN_LATCH,
 } PMUEventType;
 
 /*****************************************************************************/
@@ -388,6 +389,9 @@ typedef enum {
 #define MMCR1_PMC4SEL_START 56
 #define MMCR1_PMC4EVT_EXTR (64 - MMCR1_PMC4SEL_START - MMCR1_EVT_SIZE)
 
+/* PMU uses CTRL_RUN to sample PM_RUN_INST_CMPL */
+#define CTRL_RUN PPC_BIT(63)
+
 /* LPCR bits */
 #define LPCR_VPM0         PPC_BIT(0)
 #define LPCR_VPM1         PPC_BIT(1)

target/ppc/cpu_init.c

@@ -6182,7 +6182,7 @@ static void register_book3s_ctrl_sprs(CPUPPCState *env)
 {
     spr_register(env, SPR_CTRL, "SPR_CTRL",
                  SPR_NOACCESS, SPR_NOACCESS,
-                 SPR_NOACCESS, &spr_write_generic,
+                 SPR_NOACCESS, &spr_write_CTRL,
                  0x00000000);
     spr_register(env, SPR_UCTRL, "SPR_UCTRL",
                  &spr_read_ureg, SPR_NOACCESS,

target/ppc/power8-pmu.c

@@ -96,6 +96,15 @@ static PMUEventType pmc_get_event(CPUPPCState *env, int sprn)
             evt_type = PMU_EVENT_CYCLES;
         }
         break;
+    case 0xFA:
+        /*
+         * PMC4SEL = 0xFA is the "instructions completed
+         * with run latch set" event.
+         */
+        if (sprn == SPR_POWER_PMC4) {
+            evt_type = PMU_EVENT_INSN_RUN_LATCH;
+        }
+        break;
     case 0xFE:
         /*
          * PMC1SEL = 0xFE is the architected PowerISA v3.1
@@ -117,7 +126,8 @@ bool pmu_insn_cnt_enabled(CPUPPCState *env)
     int sprn;
 
     for (sprn = SPR_POWER_PMC1; sprn <= SPR_POWER_PMC5; sprn++) {
-        if (pmc_get_event(env, sprn) == PMU_EVENT_INSTRUCTIONS) {
+        if (pmc_get_event(env, sprn) == PMU_EVENT_INSTRUCTIONS ||
+            pmc_get_event(env, sprn) == PMU_EVENT_INSN_RUN_LATCH) {
             return true;
         }
     }
@@ -132,11 +142,22 @@ static bool pmu_increment_insns(CPUPPCState *env, uint32_t num_insns)
 
     /* PMC6 never counts instructions */
     for (sprn = SPR_POWER_PMC1; sprn <= SPR_POWER_PMC5; sprn++) {
-        if (pmc_get_event(env, sprn) != PMU_EVENT_INSTRUCTIONS) {
+        PMUEventType evt_type = pmc_get_event(env, sprn);
+        bool insn_event = evt_type == PMU_EVENT_INSTRUCTIONS ||
+                          evt_type == PMU_EVENT_INSN_RUN_LATCH;
+
+        if (pmc_is_inactive(env, sprn) || !insn_event) {
             continue;
         }
 
-        env->spr[sprn] += num_insns;
+        if (evt_type == PMU_EVENT_INSTRUCTIONS) {
+            env->spr[sprn] += num_insns;
+        }
+
+        if (evt_type == PMU_EVENT_INSN_RUN_LATCH &&
+            env->spr[SPR_CTRL] & CTRL_RUN) {
+            env->spr[sprn] += num_insns;
+        }
 
         if (env->spr[sprn] >= PMC_COUNTER_NEGATIVE_VAL &&
             pmc_has_overflow_enabled(env, sprn)) {

target/ppc/spr_tcg.h

@@ -28,6 +28,7 @@ void spr_write_generic(DisasContext *ctx, int sprn, int gprn);
 void spr_write_MMCR0(DisasContext *ctx, int sprn, int gprn);
 void spr_write_MMCR1(DisasContext *ctx, int sprn, int gprn);
 void spr_write_PMC(DisasContext *ctx, int sprn, int gprn);
+void spr_write_CTRL(DisasContext *ctx, int sprn, int gprn);
 void spr_read_xer(DisasContext *ctx, int gprn, int sprn);
 void spr_write_xer(DisasContext *ctx, int sprn, int gprn);
 void spr_read_lr(DisasContext *ctx, int gprn, int sprn);

target/ppc/translate.c

@@ -403,6 +403,18 @@ void spr_write_generic(DisasContext *ctx, int sprn, int gprn)
     spr_store_dump_spr(sprn);
 }
 
+void spr_write_CTRL(DisasContext *ctx, int sprn, int gprn)
+{
+    spr_write_generic(ctx, sprn, gprn);
+
+    /*
+     * SPR_CTRL writes must force a new translation block,
+     * allowing the PMU to calculate the run latch events with
+     * more accuracy.
+     */
+    ctx->base.is_jmp = DISAS_EXIT_UPDATE;
+}
+
 #if !defined(CONFIG_USER_ONLY)
 void spr_write_generic32(DisasContext *ctx, int sprn, int gprn)
 {