[PATCH v2] target/riscv: pmp: Ignore writes when RW=01

[Mayuresh Chitale]

As per the Priv spec: "The R, W, and X fields form a collective WARL
field for which the combinations with R=0 and W=1 are reserved."
However currently such writes are not ignored as ought to be. The
combinations with RW=01 are allowed only when the Smepmp extension
is enabled and mseccfg.MML is set.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
---
 target/riscv/pmp.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
index 5b14eb511a..8e25f145e0 100644
--- a/target/riscv/pmp.c
+++ b/target/riscv/pmp.c
@@ -120,6 +120,11 @@ static void pmp_write_cfg(CPURISCVState *env, uint32_t 
pmp_index, uint8_t val)
         if (locked) {
             qemu_log_mask(LOG_GUEST_ERROR, "ignoring pmpcfg write - locked\n");
         } else {
+            /* If !mseccfg.MML then ignore writes with encoding RW=01 */
+            if ((val & PMP_WRITE) && !(val & PMP_READ) &&
+                !MSECCFG_MML_ISSET(env)) {
+                val &= ~(PMP_WRITE | PMP_READ);
+            }
             env->pmp_state.pmp[pmp_index].cfg_reg = val;
             pmp_update_rule(env, pmp_index);
         }
-- 
2.34.1