Re: [PATCH 2/3] target/riscv: Enforce WARL behavior for scounteren/hcounteren

[Daniel Henrique Barboza]

On 4/29/24 16:28, Atish Patra wrote:

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 <ati...@rivosinc.com>
---

Reviewed-by: Daniel Henrique Barboza <dbarb...@ventanamicro.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 68ca31aff47d..a01911541d67 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -2843,7 +2843,11 @@ 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;
  }

@@ -3475,7 +3479,11 @@ 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;
  }