[PATCH v6 06/10] target/ppc: PMU: handle setting of PMCs while running

[Daniel Henrique Barboza]

The initial PMU support were made under the assumption that the counters
would be set before running the PMU and read after either freezing the
PMU manually or via a performance monitor alert.

Turns out that some EBB powerpc kernel tests set the counters after
unfreezing the counters. Setting a PMC value when the PMU is running
means that, at that moment, the baseline for calculating cycle
events needs to be updated. Updating this baseline means that we need
to update all the PMCs with their actual value at that moment. Any
existing counter negative timer needs to be discarded an a new one,
with the updated values, must be set again.

This patch does that via a new 'helper_store_pmc()' that is called in
the mtspr() callbacks of PMU counters.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 target/ppc/cpu_init.c            | 12 ++++++------
 target/ppc/helper.h              |  1 +
 target/ppc/power8-pmu-regs.c.inc | 16 +++++++++++++++-
 target/ppc/power8-pmu.c          | 18 ++++++++++++++++++
 target/ppc/spr_tcg.h             |  1 +
 5 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/target/ppc/cpu_init.c b/target/ppc/cpu_init.c
index e4010213e2..881f39ff76 100644
--- a/target/ppc/cpu_init.c
+++ b/target/ppc/cpu_init.c
@@ -6832,27 +6832,27 @@ static void register_book3s_pmu_sup_sprs(CPUPPCState 
*env)
                      KVM_REG_PPC_MMCRA, 0x00000000);
     spr_register_kvm(env, SPR_POWER_PMC1, "PMC1",
                      SPR_NOACCESS, SPR_NOACCESS,
-                     &spr_read_generic, &spr_write_generic,
+                     &spr_read_generic, &spr_write_PMC,
                      KVM_REG_PPC_PMC1, 0x00000000);
     spr_register_kvm(env, SPR_POWER_PMC2, "PMC2",
                      SPR_NOACCESS, SPR_NOACCESS,
-                     &spr_read_generic, &spr_write_generic,
+                     &spr_read_generic, &spr_write_PMC,
                      KVM_REG_PPC_PMC2, 0x00000000);
     spr_register_kvm(env, SPR_POWER_PMC3, "PMC3",
                      SPR_NOACCESS, SPR_NOACCESS,
-                     &spr_read_generic, &spr_write_generic,
+                     &spr_read_generic, &spr_write_PMC,
                      KVM_REG_PPC_PMC3, 0x00000000);
     spr_register_kvm(env, SPR_POWER_PMC4, "PMC4",
                      SPR_NOACCESS, SPR_NOACCESS,
-                     &spr_read_generic, &spr_write_generic,
+                     &spr_read_generic, &spr_write_PMC,
                      KVM_REG_PPC_PMC4, 0x00000000);
     spr_register_kvm(env, SPR_POWER_PMC5, "PMC5",
                      SPR_NOACCESS, SPR_NOACCESS,
-                     &spr_read_generic, &spr_write_generic,
+                     &spr_read_generic, &spr_write_PMC,
                      KVM_REG_PPC_PMC5, 0x00000000);
     spr_register_kvm(env, SPR_POWER_PMC6, "PMC6",
                      SPR_NOACCESS, SPR_NOACCESS,
-                     &spr_read_generic, &spr_write_generic,
+                     &spr_read_generic, &spr_write_PMC,
                      KVM_REG_PPC_PMC6, 0x00000000);
     spr_register_kvm(env, SPR_POWER_SIAR, "SIAR",
                      SPR_NOACCESS, SPR_NOACCESS,
diff --git a/target/ppc/helper.h b/target/ppc/helper.h
index f397c05f65..ce05470fd4 100644
--- a/target/ppc/helper.h
+++ b/target/ppc/helper.h
@@ -21,6 +21,7 @@ DEF_HELPER_1(hrfid, void, env)
 DEF_HELPER_2(store_lpcr, void, env, tl)
 DEF_HELPER_2(store_pcr, void, env, tl)
 DEF_HELPER_2(store_mmcr0, void, env, tl)
+DEF_HELPER_3(store_pmc, void, env, i32, i64)
 DEF_HELPER_2(insns_inc, void, env, i32)
 #endif
 DEF_HELPER_1(check_tlb_flush_local, void, env)
diff --git a/target/ppc/power8-pmu-regs.c.inc b/target/ppc/power8-pmu-regs.c.inc
index a92437b0c4..3406649130 100644
--- a/target/ppc/power8-pmu-regs.c.inc
+++ b/target/ppc/power8-pmu-regs.c.inc
@@ -212,13 +212,23 @@ void spr_read_PMC56_ureg(DisasContext *ctx, int gprn, int 
sprn)
     spr_read_PMC14_ureg(ctx, gprn, sprn);
 }
 
+void spr_write_PMC(DisasContext *ctx, int sprn, int gprn)
+{
+    TCGv_i32 t_sprn = tcg_const_i32(sprn);
+
+    gen_icount_io_start(ctx);
+    gen_helper_store_pmc(cpu_env, t_sprn, cpu_gpr[gprn]);
+
+    tcg_temp_free_i32(t_sprn);
+}
+
 void spr_write_PMC14_ureg(DisasContext *ctx, int sprn, int gprn)
 {
     if (!spr_groupA_write_allowed(ctx)) {
         return;
     }
 
-    spr_write_ureg(ctx, sprn, gprn);
+    spr_write_PMC(ctx, sprn + 0x10, gprn);
 }
 
 void spr_write_PMC56_ureg(DisasContext *ctx, int sprn, int gprn)
@@ -286,4 +296,8 @@ void spr_write_MMCR0(DisasContext *ctx, int sprn, int gprn)
 {
     spr_write_generic(ctx, sprn, gprn);
 }
+void spr_write_PMC(DisasContext *ctx, int sprn, int gprn)
+{
+    spr_write_generic(ctx, sprn, gprn);
+}
 #endif /* defined(TARGET_PPC64) && !defined(CONFIG_USER_ONLY) */
diff --git a/target/ppc/power8-pmu.c b/target/ppc/power8-pmu.c
index e43a74cc66..ed7fd0c898 100644
--- a/target/ppc/power8-pmu.c
+++ b/target/ppc/power8-pmu.c
@@ -344,4 +344,22 @@ void cpu_ppc_pmu_init(CPUPPCState *env)
     }
 }
 
+void helper_store_pmc(CPUPPCState *env, uint32_t sprn, uint64_t value)
+{
+    bool pmu_frozen = env->spr[SPR_POWER_MMCR0] & MMCR0_FC;
+
+    if (pmu_frozen) {
+        env->spr[sprn] = value;
+        return;
+    }
+
+    /*
+     * Update counters with the events counted so far, define
+     * the new value of the PMC and start a new cycle count
+     * session.
+     */
+    pmu_update_cycles(env, env->spr[SPR_POWER_MMCR0]);
+    env->spr[sprn] = value;
+    start_cycle_count_session(env);
+}
 #endif /* defined(TARGET_PPC64) && !defined(CONFIG_USER_ONLY) */
diff --git a/target/ppc/spr_tcg.h b/target/ppc/spr_tcg.h
index fdc6adfc31..aae57baf23 100644
--- a/target/ppc/spr_tcg.h
+++ b/target/ppc/spr_tcg.h
@@ -27,6 +27,7 @@ void spr_read_generic(DisasContext *ctx, int gprn, int sprn);
 void spr_write_generic(DisasContext *ctx, int sprn, int gprn);
 void spr_write_MMCR0(DisasContext *ctx, int sprn, int gprn);
 void spr_write_CTRL(DisasContext *ctx, int sprn, int gprn);
+void spr_write_PMC(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);
-- 
2.31.1