[PATCH 1/2] target/riscv: Expose "virt" register for GDB for reads

[Jim Shu]

This patch enables a debugger to read current virtualization mode via
virtual "virt" register. After it, we could get full current privilege
mode via both "priv" and "virt" register.

Extend previous commit ab9056ff9bdb3f95db6e7a666d10522d289f14ec to
support H-extension.

Signed-off-by: Jim Shu <jim.shu@sifive.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
---
 gdb-xml/riscv-32bit-virtual.xml |  1 +
 gdb-xml/riscv-64bit-virtual.xml |  1 +
 target/riscv/gdbstub.c          | 12 ++++++++----
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/gdb-xml/riscv-32bit-virtual.xml b/gdb-xml/riscv-32bit-virtual.xml
index 905f1c555d..d44b6ca2dc 100644
--- a/gdb-xml/riscv-32bit-virtual.xml
+++ b/gdb-xml/riscv-32bit-virtual.xml
@@ -8,4 +8,5 @@
 <!DOCTYPE feature SYSTEM "gdb-target.dtd">
 <feature name="org.gnu.gdb.riscv.virtual">
   <reg name="priv" bitsize="32"/>
+  <reg name="virt" bitsize="32"/>
 </feature>
diff --git a/gdb-xml/riscv-64bit-virtual.xml b/gdb-xml/riscv-64bit-virtual.xml
index 62d86c237b..7c9b63d5b6 100644
--- a/gdb-xml/riscv-64bit-virtual.xml
+++ b/gdb-xml/riscv-64bit-virtual.xml
@@ -8,4 +8,5 @@
 <!DOCTYPE feature SYSTEM "gdb-target.dtd">
 <feature name="org.gnu.gdb.riscv.virtual">
   <reg name="priv" bitsize="64"/>
+  <reg name="virt" bitsize="64"/>
 </feature>
diff --git a/target/riscv/gdbstub.c b/target/riscv/gdbstub.c
index 6048541606..1755fd9d51 100644
--- a/target/riscv/gdbstub.c
+++ b/target/riscv/gdbstub.c
@@ -187,13 +187,17 @@ static int riscv_gdb_set_csr(CPURISCVState *env, uint8_t 
*mem_buf, int n)
 
 static int riscv_gdb_get_virtual(CPURISCVState *cs, GByteArray *buf, int n)
 {
-    if (n == 0) {
 #ifdef CONFIG_USER_ONLY
+    if (n >= 0 && n <= 1) {
         return gdb_get_regl(buf, 0);
+    }
 #else
+    if (n == 0) {
         return gdb_get_regl(buf, cs->priv);
-#endif
+    } else if (n == 1) {
+        return gdb_get_regl(buf, riscv_cpu_virt_enabled(cs));
     }
+#endif
     return 0;
 }
 
@@ -328,13 +332,13 @@ void riscv_cpu_register_gdb_regs_for_features(CPUState 
*cs)
     case MXL_RV32:
         gdb_register_coprocessor(cs, riscv_gdb_get_virtual,
                                  riscv_gdb_set_virtual,
-                                 1, "riscv-32bit-virtual.xml", 0);
+                                 2, "riscv-32bit-virtual.xml", 0);
         break;
     case MXL_RV64:
     case MXL_RV128:
         gdb_register_coprocessor(cs, riscv_gdb_get_virtual,
                                  riscv_gdb_set_virtual,
-                                 1, "riscv-64bit-virtual.xml", 0);
+                                 2, "riscv-64bit-virtual.xml", 0);
         break;
     default:
         g_assert_not_reached();
-- 
2.17.1