[PATCH 3/3] target/riscv: support 'x-k' in cpu option

[Chih-Min Chao <chihmin.chao@sifive.com>]

zfh extension is still a draft and is not included in master spec. The
related field, 'k', in MISA is also undecided but has been discussed in
reference link.

  ref:
     zfh spec: https://github.com/riscv/riscv-isa-manual/tree/zfh
     misa field: https://github.com/riscv/riscv-isa-manual/issues/414

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>
---
 target/riscv/cpu.c | 4 ++++
 target/riscv/cpu.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 228b9bd..8ad8782 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -469,6 +469,9 @@ static void riscv_cpu_realize(DeviceState *dev, Error **errp)
             }
             set_vext_version(env, vext_version);
         }
+        if (cpu->cfg.ext_k) {
+            target_misa |= RVZfh;
+        }
 
         set_misa(env, RVXLEN | target_misa);
     }
@@ -509,6 +512,7 @@ static Property riscv_cpu_properties[] = {
     /* This is experimental so mark with 'x-' */
     DEFINE_PROP_BOOL("x-h", RISCVCPU, cfg.ext_h, false),
     DEFINE_PROP_BOOL("x-v", RISCVCPU, cfg.ext_v, false),
+    DEFINE_PROP_BOOL("x-k", RISCVCPU, cfg.ext_k, false),
     DEFINE_PROP_BOOL("Counters", RISCVCPU, cfg.ext_counters, true),
     DEFINE_PROP_BOOL("Zifencei", RISCVCPU, cfg.ext_ifencei, true),
     DEFINE_PROP_BOOL("Zicsr", RISCVCPU, cfg.ext_icsr, true),
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 6a077c1..bdef2a8 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -281,6 +281,7 @@ typedef struct RISCVCPU {
         bool ext_u;
         bool ext_h;
         bool ext_v;
+        bool ext_k;
         bool ext_counters;
         bool ext_ifencei;
         bool ext_icsr;
-- 
2.7.4