[PATCH 2/3] target/riscv: Fix pointer masking PMM field selection logic

[frank . chang]

From: Frank Chang <frank.ch...@sifive.com>

mstatus.MPV only records the previous virtualization state, and does not
affect pointer masking according to the Zjpm specification.

This patch rewrites riscv_pm_get_pmm() to follow the architectural
definition of Smmpm, Smnpm, and Ssnpm.

The resulting PMM source for each mode is summarized below:

  * Smmpm + Smnpm + Ssnpm:
      M-mode:  mseccfg.PMM
      S-mode:  menvcfg.PMM
      U-mode:  senvcfg.PMM
      VS-mode: henvcfg.PMM
      VU-mode: senvcfg.PMM

  * Smmpm + Smnpm (RVS implemented):
      M-mode:  mseccfg.PMM
      S-mode:  menvcfg.PMM
      U/VS/VU: disabled (Ssnpm not present)

  * Smmpm + Smnpm (RVS not implemented):
      M-mode:  mseccfg.PMM
      U-mode:  menvcfg.PMM
      S/VS/VU: disabled (no S-mode)

  * Smmpm only:
      M-mode:  mseccfg.PMM
      Other existing modes: pointer masking disabled

Signed-off-by: Frank Chang <frank.ch...@sifive.com>
---
 target/riscv/cpu_helper.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index dd6c861a90e..112093012b0 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -154,22 +154,30 @@ RISCVPmPmm riscv_pm_get_pmm(CPURISCVState *env)
         }
         break;
     case PRV_S:
-        if (riscv_cpu_cfg(env)->ext_smnpm) {
-            if (get_field(env->mstatus, MSTATUS_MPV)) {
-                return get_field(env->henvcfg, HENVCFG_PMM);
-            } else {
+        if (!env->virt_enabled) {
+            if (riscv_cpu_cfg(env)->ext_smnpm) {
                 return get_field(env->menvcfg, MENVCFG_PMM);
             }
+        } else {
+            if (riscv_cpu_cfg(env)->ext_ssnpm) {
+                return get_field(env->henvcfg, HENVCFG_PMM);
+            }
         }
         break;
     case PRV_U:
-        if (riscv_has_ext(env, RVS)) {
+        if (!env->virt_enabled) {
             if (riscv_cpu_cfg(env)->ext_ssnpm) {
                 return get_field(env->senvcfg, SENVCFG_PMM);
             }
-        } else {
+
             if (riscv_cpu_cfg(env)->ext_smnpm) {
-                return get_field(env->menvcfg, MENVCFG_PMM);
+                if (!riscv_has_ext(env, RVS)) {
+                    return get_field(env->menvcfg, MENVCFG_PMM);
+                }
+            }
+        } else {
+            if (riscv_cpu_cfg(env)->ext_ssnpm) {
+                return get_field(env->senvcfg, SENVCFG_PMM);
             }
         }
         break;
-- 
2.43.0