[PATCH v4 4/5] target/riscv: Add cycle & instret privilege mode filtering support

[Atish Patra]

From: Kaiwen Xue <kaiwenx@rivosinc.com>

QEMU only calculates dummy cycles and instructions, so there is no
actual means to stop the icount in QEMU. Hence this patch merely adds
the functionality of accessing the cfg registers, and cause no actual
effects on the counting of cycle and instret counters.

Signed-off-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Signed-off-by: Kaiwen Xue <kaiwenx@rivosinc.com>
---
 target/riscv/csr.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 283468bbc652..3bd4aa22374f 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -233,6 +233,24 @@ static RISCVException sscofpmf_32(CPURISCVState *env, int 
csrno)
     return sscofpmf(env, csrno);
 }
 
+static RISCVException smcntrpmf(CPURISCVState *env, int csrno)
+{
+    if (!riscv_cpu_cfg(env)->ext_smcntrpmf) {
+        return RISCV_EXCP_ILLEGAL_INST;
+    }
+
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException smcntrpmf_32(CPURISCVState *env, int csrno)
+{
+    if (riscv_cpu_mxl(env) != MXL_RV32) {
+        return RISCV_EXCP_ILLEGAL_INST;
+    }
+
+    return smcntrpmf(env, csrno);
+}
+
 static RISCVException any(CPURISCVState *env, int csrno)
 {
     return RISCV_EXCP_NONE;
@@ -818,6 +836,54 @@ static int read_hpmcounterh(CPURISCVState *env, int csrno, 
target_ulong *val)
 
 #else /* CONFIG_USER_ONLY */
 
+static int read_mcyclecfg(CPURISCVState *env, int csrno, target_ulong *val)
+{
+    *val = env->mcyclecfg;
+    return RISCV_EXCP_NONE;
+}
+
+static int write_mcyclecfg(CPURISCVState *env, int csrno, target_ulong val)
+{
+    env->mcyclecfg = val;
+    return RISCV_EXCP_NONE;
+}
+
+static int read_mcyclecfgh(CPURISCVState *env, int csrno, target_ulong *val)
+{
+    *val = env->mcyclecfgh;
+    return RISCV_EXCP_NONE;
+}
+
+static int write_mcyclecfgh(CPURISCVState *env, int csrno, target_ulong val)
+{
+    env->mcyclecfgh = val;
+    return RISCV_EXCP_NONE;
+}
+
+static int read_minstretcfg(CPURISCVState *env, int csrno, target_ulong *val)
+{
+    *val = env->minstretcfg;
+    return RISCV_EXCP_NONE;
+}
+
+static int write_minstretcfg(CPURISCVState *env, int csrno, target_ulong val)
+{
+    env->minstretcfg = val;
+    return RISCV_EXCP_NONE;
+}
+
+static int read_minstretcfgh(CPURISCVState *env, int csrno, target_ulong *val)
+{
+    *val = env->minstretcfgh;
+    return RISCV_EXCP_NONE;
+}
+
+static int write_minstretcfgh(CPURISCVState *env, int csrno, target_ulong val)
+{
+    env->minstretcfgh = val;
+    return RISCV_EXCP_NONE;
+}
+
 static int read_mhpmevent(CPURISCVState *env, int csrno, target_ulong *val)
 {
     int evt_index = csrno - CSR_MCOUNTINHIBIT;
@@ -4922,6 +4988,13 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
                              write_mcountinhibit,
                              .min_priv_ver = PRIV_VERSION_1_11_0       },
 
+    [CSR_MCYCLECFG]      = { "mcyclecfg",   smcntrpmf, read_mcyclecfg,
+                             write_mcyclecfg,
+                             .min_priv_ver = PRIV_VERSION_1_12_0       },
+    [CSR_MINSTRETCFG]    = { "minstretcfg", smcntrpmf, read_minstretcfg,
+                             write_minstretcfg,
+                             .min_priv_ver = PRIV_VERSION_1_12_0       },
+
     [CSR_MHPMEVENT3]     = { "mhpmevent3",     any,    read_mhpmevent,
                              write_mhpmevent                           },
     [CSR_MHPMEVENT4]     = { "mhpmevent4",     any,    read_mhpmevent,
@@ -4981,6 +5054,13 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_MHPMEVENT31]    = { "mhpmevent31",    any,    read_mhpmevent,
                              write_mhpmevent                           },
 
+    [CSR_MCYCLECFGH]     = { "mcyclecfgh",   smcntrpmf_32, read_mcyclecfgh,
+                             write_mcyclecfgh,
+                             .min_priv_ver = PRIV_VERSION_1_12_0        },
+    [CSR_MINSTRETCFGH]   = { "minstretcfgh", smcntrpmf_32, read_minstretcfgh,
+                             write_minstretcfgh,
+                             .min_priv_ver = PRIV_VERSION_1_12_0        },
+
     [CSR_MHPMEVENT3H]    = { "mhpmevent3h",    sscofpmf_32,  read_mhpmeventh,
                              write_mhpmeventh,
                              .min_priv_ver = PRIV_VERSION_1_12_0        },
-- 
2.34.1