[PATCH v2 08/10] target/arm: Implement FEAT_PMUv3p5 cycle counter disable bits

[Peter Maydell]

FEAT_PMUv3p5 introduces new bits which disable the cycle
counter from counting:
 * MDCR_EL2.HCCD disables the counter when in EL2
 * MDCR_EL3.SCCD disables the counter when Secure

Add the code to support these bits.

(Note that there is a third documented counter-disable
bit, MDCR_EL3.MCCD, which disables the counter when in
EL3. This is not present until FEAT_PMUv3p7, so is
out of scope for now.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
v1->v2: Get the MDCR_EL3 bit right; v1 implemented something
more like MDCR_EL3.MCCD.
---
 target/arm/cpu.h    | 20 ++++++++++++++++++++
 target/arm/helper.c | 21 +++++++++++++++++----
 2 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 122ec8a47ec..1f6ccc6f217 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1332,6 +1332,8 @@ FIELD(CPTR_EL3, TTA, 20, 1)
 FIELD(CPTR_EL3, TAM, 30, 1)
 FIELD(CPTR_EL3, TCPAC, 31, 1)
 
+#define MDCR_SCCD     (1U << 23)  /* MDCR_EL3 */
+#define MDCR_HCCD     (1U << 23)  /* MDCR_EL2 */
 #define MDCR_EPMAD    (1U << 21)
 #define MDCR_EDAD     (1U << 20)
 #define MDCR_SPME     (1U << 17)  /* MDCR_EL3 */
@@ -3724,6 +3726,13 @@ static inline bool isar_feature_aa32_pmuv3p4(const 
ARMISARegisters *id)
         FIELD_EX32(id->id_dfr0, ID_DFR0, PERFMON) != 0xf;
 }
 
+static inline bool isar_feature_aa32_pmuv3p5(const ARMISARegisters *id)
+{
+    /* 0xf means "non-standard IMPDEF PMU" */
+    return FIELD_EX32(id->id_dfr0, ID_DFR0, PERFMON) >= 6 &&
+        FIELD_EX32(id->id_dfr0, ID_DFR0, PERFMON) != 0xf;
+}
+
 static inline bool isar_feature_aa32_hpd(const ARMISARegisters *id)
 {
     return FIELD_EX32(id->id_mmfr4, ID_MMFR4, HPDS) != 0;
@@ -4048,6 +4057,12 @@ static inline bool isar_feature_aa64_pmuv3p4(const 
ARMISARegisters *id)
         FIELD_EX64(id->id_aa64dfr0, ID_AA64DFR0, PMUVER) != 0xf;
 }
 
+static inline bool isar_feature_aa64_pmuv3p5(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->id_aa64dfr0, ID_AA64DFR0, PMUVER) >= 6 &&
+        FIELD_EX64(id->id_aa64dfr0, ID_AA64DFR0, PMUVER) != 0xf;
+}
+
 static inline bool isar_feature_aa64_rcpc_8_3(const ARMISARegisters *id)
 {
     return FIELD_EX64(id->id_aa64isar1, ID_AA64ISAR1, LRCPC) != 0;
@@ -4221,6 +4236,11 @@ static inline bool isar_feature_any_pmuv3p4(const 
ARMISARegisters *id)
     return isar_feature_aa64_pmuv3p4(id) || isar_feature_aa32_pmuv3p4(id);
 }
 
+static inline bool isar_feature_any_pmuv3p5(const ARMISARegisters *id)
+{
+    return isar_feature_aa64_pmuv3p5(id) || isar_feature_aa32_pmuv3p5(id);
+}
+
 static inline bool isar_feature_any_ccidx(const ARMISARegisters *id)
 {
     return isar_feature_aa64_ccidx(id) || isar_feature_aa32_ccidx(id);
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 5212750b378..d22debcd57b 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -1084,8 +1084,8 @@ static CPAccessResult pmreg_access_ccntr(CPUARMState *env,
  * We use these to decide whether we need to wrap a write to MDCR_EL2
  * or MDCR_EL3 in pmu_op_start()/pmu_op_finish() calls.
  */
-#define MDCR_EL2_PMU_ENABLE_BITS (MDCR_HPME | MDCR_HPMD | MDCR_HPMN)
-#define MDCR_EL3_PMU_ENABLE_BITS (MDCR_SPME)
+#define MDCR_EL2_PMU_ENABLE_BITS (MDCR_HPME | MDCR_HPMD | MDCR_HPMN | 
MDCR_HCCD)
+#define MDCR_EL3_PMU_ENABLE_BITS (MDCR_SPME | MDCR_SCCD)
 
 /* Returns true if the counter (pass 31 for PMCCNTR) should count events using
  * the current EL, security state, and register configuration.
@@ -1120,8 +1120,21 @@ static bool pmu_counter_enabled(CPUARMState *env, 
uint8_t counter)
         prohibited = prohibited || !(env->cp15.mdcr_el3 & MDCR_SPME);
     }
 
-    if (prohibited && counter == 31) {
-        prohibited = env->cp15.c9_pmcr & PMCRDP;
+    if (counter == 31) {
+        /*
+         * The cycle counter defaults to running. PMCR.DP says "disable
+         * the cycle counter when event counting is prohibited".
+         * Some MDCR bits disable the cycle counter specifically.
+         */
+        prohibited = prohibited && env->cp15.c9_pmcr & PMCRDP;
+        if (cpu_isar_feature(any_pmuv3p5, env_archcpu(env))) {
+            if (secure) {
+                prohibited = prohibited || (env->cp15.mdcr_el3 & MDCR_SCCD);
+            }
+            if (el == 2) {
+                prohibited = prohibited || (mdcr_el2 & MDCR_HCCD);
+            }
+        }
     }
 
     if (counter == 31) {
-- 
2.25.1