From: Atish Patra <atishp@rivosinc.com>

scounteren/hcountern are also WARL registers similar to mcountern.
Only set the bits for the available counters during the write to
preserve the WARL behavior.

Signed-off-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20240711-smcntrpmf_v7-v8-9-b7c38ae7b263@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
 target/riscv/csr.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index b7a24f9c60..d6c5b73afd 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -3063,7 +3063,11 @@ static RISCVException read_scounteren(CPURISCVState *env, int csrno,
 static RISCVException write_scounteren(CPURISCVState *env, int csrno,
                                        target_ulong val)
 {
-    env->scounteren = val;
+    RISCVCPU *cpu = env_archcpu(env);
+
+    /* WARL register - disable unavailable counters */
+    env->scounteren = val & (cpu->pmu_avail_ctrs | COUNTEREN_CY | COUNTEREN_TM |
+                             COUNTEREN_IR);
     return RISCV_EXCP_NONE;
 }
 
@@ -3722,7 +3726,11 @@ static RISCVException read_hcounteren(CPURISCVState *env, int csrno,
 static RISCVException write_hcounteren(CPURISCVState *env, int csrno,
                                        target_ulong val)
 {
-    env->hcounteren = val;
+    RISCVCPU *cpu = env_archcpu(env);
+
+    /* WARL register - disable unavailable counters */
+    env->hcounteren = val & (cpu->pmu_avail_ctrs | COUNTEREN_CY | COUNTEREN_TM |
+                             COUNTEREN_IR);
     return RISCV_EXCP_NONE;
 }
 
-- 
2.45.2