[PATCH v3 4/6] target/riscv: Add "pmu-mask" property to replace "pmu-num"

[Rob Bradford]

Using a mask instead of the number of PMU devices supports the accurate
emulation of platforms that have a discontinuous set of PMU counters.

Generate a warning if the old property changed from the default but
still go ahead and use it to generate the mask if the user has changed
it from the default

Signed-off-by: Rob Bradford <rbradf...@rivosinc.com>
---
 target/riscv/cpu.c     |  5 +++--
 target/riscv/cpu_cfg.h |  3 ++-
 target/riscv/machine.c |  2 +-
 target/riscv/pmu.c     | 20 ++++++++++++++++----
 4 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index c9d8fc12fe..420673b491 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -1487,7 +1487,7 @@ static void riscv_cpu_realize_tcg(DeviceState *dev, Error 
**errp)
         riscv_timer_init(cpu);
     }
 
-    if (cpu->cfg.pmu_num) {
+    if (cpu->cfg.pmu_mask) {
         riscv_pmu_init(cpu, &local_err);
         if (local_err != NULL) {
             error_propagate(errp, local_err);
@@ -1812,7 +1812,8 @@ static void riscv_cpu_add_misa_properties(Object *cpu_obj)
 
 static Property riscv_cpu_extensions[] = {
     /* Defaults for standard extensions */
-    DEFINE_PROP_UINT8("pmu-num", RISCVCPU, cfg.pmu_num, 16),
+    DEFINE_PROP_UINT8("pmu-num", RISCVCPU, cfg.pmu_num, 16), /* Deprecated */
+    DEFINE_PROP_UINT32("pmu-mask", RISCVCPU, cfg.pmu_mask, MAKE_64BIT_MASK(3, 
16)),
     DEFINE_PROP_BOOL("sscofpmf", RISCVCPU, cfg.ext_sscofpmf, false),
     DEFINE_PROP_BOOL("Zifencei", RISCVCPU, cfg.ext_ifencei, true),
     DEFINE_PROP_BOOL("Zicsr", RISCVCPU, cfg.ext_icsr, true),
diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
index 0e6a0f245c..d273487040 100644
--- a/target/riscv/cpu_cfg.h
+++ b/target/riscv/cpu_cfg.h
@@ -123,7 +123,8 @@ struct RISCVCPUConfig {
     bool ext_xtheadsync;
     bool ext_XVentanaCondOps;
 
-    uint8_t pmu_num;
+    uint8_t pmu_num; /* Deprecated */
+    uint32_t pmu_mask;
     char *priv_spec;
     char *user_spec;
     char *bext_spec;
diff --git a/target/riscv/machine.c b/target/riscv/machine.c
index c7c862cdd3..9f6e3f7a6d 100644
--- a/target/riscv/machine.c
+++ b/target/riscv/machine.c
@@ -313,7 +313,7 @@ static bool pmu_needed(void *opaque)
 {
     RISCVCPU *cpu = opaque;
 
-    return cpu->cfg.pmu_num;
+    return (cpu->cfg.pmu_mask > 0);
 }
 
 static const VMStateDescription vmstate_pmu_ctr_state = {
diff --git a/target/riscv/pmu.c b/target/riscv/pmu.c
index 7ddf4977b1..9253e5f17a 100644
--- a/target/riscv/pmu.c
+++ b/target/riscv/pmu.c
@@ -18,6 +18,7 @@
 
 #include "qemu/osdep.h"
 #include "qemu/log.h"
+#include "qemu/error-report.h"
 #include "cpu.h"
 #include "pmu.h"
 #include "sysemu/cpu-timers.h"
@@ -184,7 +185,7 @@ int riscv_pmu_incr_ctr(RISCVCPU *cpu, enum 
riscv_pmu_event_idx event_idx)
     CPURISCVState *env = &cpu->env;
     gpointer value;
 
-    if (!cpu->cfg.pmu_num) {
+    if (!cpu->cfg.pmu_mask) {
         return 0;
     }
     value = g_hash_table_lookup(cpu->pmu_event_ctr_map,
@@ -434,7 +435,13 @@ void riscv_pmu_init(RISCVCPU *cpu, Error **errp)
 {
     uint8_t pmu_num = cpu->cfg.pmu_num;
 
-    if (pmu_num > (RV_MAX_MHPMCOUNTERS - 3)) {
+    if (cpu->cfg.pmu_mask & (COUNTEREN_CY | COUNTEREN_TM | COUNTEREN_IR)) {
+        error_setg(errp, "\"pmu-mask\" contains invalid bits (0-2) set");
+        return;
+    }
+
+    if (ctpop32(cpu->cfg.pmu_mask) > (RV_MAX_MHPMCOUNTERS - 3) ||
+        (pmu_num > RV_MAX_MHPMCOUNTERS - 3)) {
         error_setg(errp, "Number of counters exceeds maximum available");
         return;
     }
@@ -445,6 +452,11 @@ void riscv_pmu_init(RISCVCPU *cpu, Error **errp)
         return;
     }
 
-    /* Create a bitmask of available programmable counters */
-    cpu->pmu_avail_ctrs = MAKE_32BIT_MASK(3, pmu_num);
+    /* Check if user set it by comparing against default */
+    if (pmu_num != 16) {
+        warn_report("\"pmu-num\" property is deprecated; use \"pmu-mask\"");
+        cpu->cfg.pmu_mask = MAKE_32BIT_MASK(3, pmu_num);
+    }
+
+    cpu->pmu_avail_ctrs = cpu->cfg.pmu_mask;
 }
-- 
2.41.0