To ensure our TLB isn't out-of-date we flush it on all virt mode
changes. Unlike priv mode this isn't saved in the mmu_idx as all
guests share V=1. The easiest option is just to flush on all changes.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
 target/riscv/cpu_helper.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 0128546e6a..81f1cc83e5 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -157,6 +157,11 @@ void riscv_cpu_set_virt_enabled(CPURISCVState *env, bool enable)
         return;
     }
 
+    /* Flush the TLB on all virt mode changes. */
+    if (((env->virt & VIRT_MODE_MASK) >> VIRT_MODE_SHIFT) != enable) {
+        tlb_flush(CPU(riscv_env_get_cpu(env)));
+    }
+
     env->virt &= ~VIRT_MODE_MASK;
     env->virt |= enable << VIRT_MODE_SHIFT;
 }
-- 
2.21.0