[PATCH 7/8] target/riscv/cpu.c: honor user choice in cpu_cfg_ext_auto_update()

[Daniel Henrique Barboza]

Add a new cpu_cfg_ext_is_user_set() helper to check if an extension was
set by the user in the command line. Use it inside
cpu_cfg_ext_auto_update() to verify if the user set a certain extension
and, if that's the case, do not change its value.

This will make us honor user choice instead of overwriting the values.
Users will then be informed whether they're using an incompatible set of
extensions instead of QEMU setting a magic value that works.

For example, we'll now error out if the user explictly set 'zce' to true
and 'zca' to false:

$ ./build/qemu-system-riscv64 -M virt -cpu rv64,zce=true,zca=false -nographic
qemu-system-riscv64: Zcf/Zcd/Zcb/Zcmp/Zcmt extensions require Zca extension

This didn't happen before because we were enabling 'zca' if 'zce' was enabled
regardless if the user explictly set 'zca' to false.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/cpu.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index a40dc865a0..644d0fdad2 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -187,6 +187,12 @@ static int cpu_cfg_ext_get_min_version(uint32_t ext_offset)
     return PRIV_VERSION_1_10_0;
 }
 
+static bool cpu_cfg_ext_is_user_set(uint32_t ext_offset)
+{
+    return g_hash_table_contains(multi_ext_user_opts,
+                                 GUINT_TO_POINTER(ext_offset));
+}
+
 static void cpu_cfg_ext_auto_update(RISCVCPU *cpu, uint32_t ext_offset,
                                     bool value)
 {
@@ -198,6 +204,10 @@ static void cpu_cfg_ext_auto_update(RISCVCPU *cpu, 
uint32_t ext_offset,
         return;
     }
 
+    if (cpu_cfg_ext_is_user_set(ext_offset)) {
+        return;
+    }
+
     if (value && env->priv_ver != PRIV_VERSION_LATEST) {
         /* Do not enable it if priv_ver is older than min_version */
         min_version = cpu_cfg_ext_get_min_version(ext_offset);
-- 
2.41.0