Enabling RVG will enable a set of extensions that we're not checking if
the user was okay enabling or not. And in this case we want to error
out, instead of ignoring, otherwise we will be inconsistent enabling RVG
without all its extensions.

After this patch, disabling ifencei or icsr while enabling RVG will
result in error:

$ ./build/qemu-system-riscv64 -M virt -cpu rv64,g=true,Zifencei=false --nographic
qemu-system-riscv64: RVG requires Zifencei but user set Zifencei to false

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
 target/riscv/cpu.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index fb8e4d6a8f..2644638b11 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -1153,9 +1153,23 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
           riscv_has_ext(env, RVA) && riscv_has_ext(env, RVF) &&
           riscv_has_ext(env, RVD) &&
           cpu->cfg.ext_icsr && cpu->cfg.ext_ifencei)) {
+
+        if (cpu_cfg_ext_is_user_set(CPU_CFG_OFFSET(ext_icsr)) &&
+            !cpu->cfg.ext_icsr) {
+            error_setg(errp, "RVG requires Zicsr but user set Zicsr to false");
+            return;
+        }
+
+        if (cpu_cfg_ext_is_user_set(CPU_CFG_OFFSET(ext_ifencei)) &&
+            !cpu->cfg.ext_ifencei) {
+            error_setg(errp, "RVG requires Zifencei but user set "
+                       "Zifencei to false");
+            return;
+        }
+
         warn_report("Setting G will also set IMAFD_Zicsr_Zifencei");
-        cpu->cfg.ext_icsr = true;
-        cpu->cfg.ext_ifencei = true;
+        cpu_cfg_ext_auto_update(cpu, CPU_CFG_OFFSET(ext_icsr), true);
+        cpu_cfg_ext_auto_update(cpu, CPU_CFG_OFFSET(ext_ifencei), true);
 
         env->misa_ext |= RVI | RVM | RVA | RVF | RVD;
         env->misa_ext_mask |= RVI | RVM | RVA | RVF | RVD;
-- 
2.41.0