[PATCH for-8.1 v4 25/25] target/riscv: handle RVG updates in write_misa()

[Daniel Henrique Barboza]

RVG is enabled when IMAFD_Zicsr_Zifencei is also enabled. Change
write_misa() to enable IMAFD if G is being written in the CSR.

Likewise, RVG should be disabled if any of IMAFD got disabled during the
process. Clear RVG in this case.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/csr.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 839862f1a8..1c0f438dfb 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -1381,6 +1381,14 @@ static RISCVException write_misa(CPURISCVState *env, int 
csrno,
         val &= RVE;
     }
 
+    if (val & RVG && !(env->misa_ext & RVG)) {
+        /*
+         * If the write wants to enable RVG, enable all its
+         * dependencies as well.
+         */
+        val |= RVI | RVM | RVA | RVF | RVD;
+    }
+
     /*
      * This flow is similar to what riscv_cpu_realize() does,
      * with the difference that we will update env->misa_ext
@@ -1396,6 +1404,12 @@ static RISCVException write_misa(CPURISCVState *env, int 
csrno,
         return RISCV_EXCP_NONE;
     }
 
+    if (!(val & RVI && val & RVM && val & RVA &&
+          val & RVF && val & RVD)) {
+        /* Disable RVG if any of its dependencies were disabled */
+        val &= ~RVG;
+    }
+
     riscv_cpu_commit_cpu_cfg(cpu, val);
 
     if (!(val & RVF)) {
-- 
2.39.2