target/riscv: Trap on writes to stimecmp from VS when hvictl.VTI=1

Per the AIA specification, writes to stimecmp from VS level should
trap when hvictl.VTI is set since the write may cause vsip.STIP to
become unset.

Fixes: 3ec0fe18a31f ("target/riscv: Add vstimecmp support")
Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20221215224541.1423431-2-abrestic@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 270de7b..62e6c4a 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -1037,6 +1037,9 @@ static RISCVException write_stimecmp(CPURISCVState *env, int csrno,
     RISCVCPU *cpu = env_archcpu(env);
 
     if (riscv_cpu_virt_enabled(env)) {
+        if (env->hvictl & HVICTL_VTI) {
+            return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
+        }
         return write_vstimecmp(env, csrno, val);
     }
 
@@ -1057,6 +1060,9 @@ static RISCVException write_stimecmph(CPURISCVState *env, int csrno,
     RISCVCPU *cpu = env_archcpu(env);
 
     if (riscv_cpu_virt_enabled(env)) {
+        if (env->hvictl & HVICTL_VTI) {
+            return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
+        }
         return write_vstimecmph(env, csrno, val);
     }