target/riscv: sync env->misa_ext* with cpu->cfg in realize()

When riscv_cpu_realize() starts we're guaranteed to have cpu->cfg.ext_N
properties updated. The same can't be said about env->misa_ext*, since
the user might enable/disable MISA extensions in the command line, and
env->misa_ext* won't caught these changes. The current solution is to
sync everything at the end of validate_set_extensions(), checking every
cpu->cfg.ext_N value to do a set_misa() in the end.

The last change we're making in the MISA cfg flags are in the G
extension logic, enabling IMAFG if cpu->cfg_ext.g is enabled. Otherwise
we're not making any changes in MISA bits ever since realize() starts.

There's no reason to postpone misa_ext updates until the end of the
validation. Let's do it earlier, during realize(), in a new helper
called riscv_cpu_sync_misa_cfg(). If cpu->cfg.ext_g is enabled, do it
again by updating env->misa_ext* directly.

This is a pre-requisite to allow riscv_cpu_validate_set_extensions() to
use riscv_has_ext() instead of cpu->cfg.ext_N to validate the MISA
extensions, which is our end goal here.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20230406180351.570807-2-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 56 insertions, 38 deletions

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index cb68916..66de3bb 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -811,12 +811,11 @@ static void riscv_cpu_disas_set_info(CPUState *s, disassemble_info *info)
 
 /*
  * Check consistency between chosen extensions while setting
- * cpu->cfg accordingly, doing a set_misa() in the end.
+ * cpu->cfg accordingly.
  */
 static void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
 {
     CPURISCVState *env = &cpu->env;
-    uint32_t ext = 0;
 
     /* Do some ISA extension error checking */
     if (cpu->cfg.ext_g && !(cpu->cfg.ext_i && cpu->cfg.ext_m &&
@@ -831,6 +830,9 @@ static void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
         cpu->cfg.ext_d = true;
         cpu->cfg.ext_icsr = true;
         cpu->cfg.ext_ifencei = true;
+
+        env->misa_ext |= RVI | RVM | RVA | RVF | RVD;
+        env->misa_ext_mask = env->misa_ext;
     }
 
     if (cpu->cfg.ext_i && cpu->cfg.ext_e) {
@@ -1022,39 +1024,8 @@ static void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
         cpu->cfg.ext_zksh = true;
     }
 
-    if (cpu->cfg.ext_i) {
-        ext |= RVI;
-    }
-    if (cpu->cfg.ext_e) {
-        ext |= RVE;
-    }
-    if (cpu->cfg.ext_m) {
-        ext |= RVM;
-    }
-    if (cpu->cfg.ext_a) {
-        ext |= RVA;
-    }
-    if (cpu->cfg.ext_f) {
-        ext |= RVF;
-    }
-    if (cpu->cfg.ext_d) {
-        ext |= RVD;
-    }
-    if (cpu->cfg.ext_c) {
-        ext |= RVC;
-    }
-    if (cpu->cfg.ext_s) {
-        ext |= RVS;
-    }
-    if (cpu->cfg.ext_u) {
-        ext |= RVU;
-    }
-    if (cpu->cfg.ext_h) {
-        ext |= RVH;
-    }
     if (cpu->cfg.ext_v) {
         int vext_version = VEXT_VERSION_1_00_0;
-        ext |= RVV;
         if (!is_power_of_2(cpu->cfg.vlen)) {
             error_setg(errp,
                        "Vector extension VLEN must be power of 2");
@@ -1092,11 +1063,6 @@ static void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
         }
         set_vext_version(env, vext_version);
     }
-    if (cpu->cfg.ext_j) {
-        ext |= RVJ;
-    }
-
-    set_misa(env, env->misa_mxl, ext);
 }
 
 #ifndef CONFIG_USER_ONLY
@@ -1181,6 +1147,50 @@ static void riscv_cpu_finalize_features(RISCVCPU *cpu, Error **errp)
 #endif
 }
 
+static void riscv_cpu_sync_misa_cfg(CPURISCVState *env)
+{
+    uint32_t ext = 0;
+
+    if (riscv_cpu_cfg(env)->ext_i) {
+        ext |= RVI;
+    }
+    if (riscv_cpu_cfg(env)->ext_e) {
+        ext |= RVE;
+    }
+    if (riscv_cpu_cfg(env)->ext_m) {
+        ext |= RVM;
+    }
+    if (riscv_cpu_cfg(env)->ext_a) {
+        ext |= RVA;
+    }
+    if (riscv_cpu_cfg(env)->ext_f) {
+        ext |= RVF;
+    }
+    if (riscv_cpu_cfg(env)->ext_d) {
+        ext |= RVD;
+    }
+    if (riscv_cpu_cfg(env)->ext_c) {
+        ext |= RVC;
+    }
+    if (riscv_cpu_cfg(env)->ext_s) {
+        ext |= RVS;
+    }
+    if (riscv_cpu_cfg(env)->ext_u) {
+        ext |= RVU;
+    }
+    if (riscv_cpu_cfg(env)->ext_h) {
+        ext |= RVH;
+    }
+    if (riscv_cpu_cfg(env)->ext_v) {
+        ext |= RVV;
+    }
+    if (riscv_cpu_cfg(env)->ext_j) {
+        ext |= RVJ;
+    }
+
+    env->misa_ext = env->misa_ext_mask = ext;
+}
+
 static void riscv_cpu_realize(DeviceState *dev, Error **errp)
 {
     CPUState *cs = CPU(dev);
@@ -1216,6 +1226,14 @@ static void riscv_cpu_realize(DeviceState *dev, Error **errp)
         set_priv_version(env, priv_version);
     }
 
+    /*
+     * We can't be sure of whether we set defaults during cpu_init()
+     * or whether the user enabled/disabled some bits via cpu->cfg
+     * flags. Sync env->misa_ext with cpu->cfg now to allow us to
+     * use just env->misa_ext later.
+     */
+    riscv_cpu_sync_misa_cfg(env);
+
     /* Force disable extensions if priv spec version does not match */
     for (i = 0; i < ARRAY_SIZE(isa_edata_arr); i++) {
         if (isa_ext_is_enabled(cpu, &isa_edata_arr[i]) &&