[PATCH v4 3/4] target/riscv: Handle Smrnmi interrupt and exception.

[Tommy Wu <tommy.wu@sifive.com>]

Signed-off-by: Frank Chang <frank.chang@sifive.com>
Signed-off-by: Tommy Wu <tommy.wu@sifive.com>
---
 target/riscv/cpu_helper.c | 57 +++++++++++++++++++++++++++++++++++----
 1 file changed, 52 insertions(+), 5 deletions(-)

diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index da477b6c99..1a926bb661 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -407,6 +407,18 @@ static int riscv_cpu_local_irq_pending(CPURISCVState *env)
     int virq;
     uint64_t irqs, pending, mie, hsie, vsie;
 
+    /* Priority: RNMI > Other interrupt. */
+    if (riscv_cpu_cfg(env)->ext_smrnmi) {
+        /* If mnstatus.NMIE == 0, all interrupts are disabled. */
+        if (!get_field(env->mnstatus, MNSTATUS_NMIE)) {
+            return RISCV_EXCP_NONE;
+        }
+
+        if (env->rnmip) {
+            return ctz64(env->rnmip); /* since non-zero */
+        }
+    }
+
     /* Determine interrupt enable state of all privilege modes */
     if (env->virt_enabled) {
         mie = 1;
@@ -452,7 +464,9 @@ static int riscv_cpu_local_irq_pending(CPURISCVState *env)
 
 bool riscv_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
 {
-    if (interrupt_request & CPU_INTERRUPT_HARD) {
+    uint32_t mask = CPU_INTERRUPT_HARD | CPU_INTERRUPT_RNMI;
+
+    if (interrupt_request & mask) {
         RISCVCPU *cpu = RISCV_CPU(cs);
         CPURISCVState *env = &cpu->env;
         int interruptno = riscv_cpu_local_irq_pending(env);
@@ -1614,6 +1628,7 @@ void riscv_cpu_do_interrupt(CPUState *cs)
     CPURISCVState *env = &cpu->env;
     bool write_gva = false;
     uint64_t s;
+    int mode;
 
     /*
      * cs->exception is 32-bits wide unlike mcause which is XLEN-bits wide
@@ -1626,6 +1641,20 @@ void riscv_cpu_do_interrupt(CPUState *cs)
     target_ulong tinst = 0;
     target_ulong htval = 0;
     target_ulong mtval2 = 0;
+    bool nmi_execp = false;
+
+    if (cpu->cfg.ext_smrnmi && env->rnmip && async) {
+        env->mnstatus = set_field(env->mnstatus, MNSTATUS_NMIE, false);
+        env->mnstatus = set_field(env->mnstatus, MNSTATUS_MNPV,
+                                  env->virt_enabled);
+        env->mnstatus = set_field(env->mnstatus, MNSTATUS_MNPP,
+                                  env->priv);
+        env->mncause = cause | ((target_ulong)1U << (TARGET_LONG_BITS - 1));
+        env->mnepc = env->pc;
+        env->pc = env->rnmi_irqvec;
+        riscv_cpu_set_mode(env, PRV_M);
+        goto handled;
+    }
 
     if  (cause == RISCV_EXCP_SEMIHOST) {
         do_common_semihosting(cs);
@@ -1712,8 +1741,20 @@ void riscv_cpu_do_interrupt(CPUState *cs)
                   __func__, env->mhartid, async, cause, env->pc, tval,
                   riscv_cpu_get_trap_name(cause, async));
 
-    if (env->priv <= PRV_S &&
-            cause < TARGET_LONG_BITS && ((deleg >> cause) & 1)) {
+    mode = env->priv <= PRV_S &&
+        cause < TARGET_LONG_BITS && ((deleg >> cause) & 1) ? PRV_S : PRV_M;
+
+    /*
+     * If the hart encounters an exception while executing in M-mode,
+     * with the mnstatus.NMIE bit clear, the program counter is set to
+     * the RNMI exception trap handler address.
+     */
+    nmi_execp = cpu->cfg.ext_smrnmi &&
+                !get_field(env->mnstatus, MNSTATUS_NMIE) &&
+                !async &&
+                mode == PRV_M;
+
+    if (mode == PRV_S) {
         /* handle the trap in S-mode */
         if (riscv_has_ext(env, RVH)) {
             uint64_t hdeleg = async ? env->hideleg : env->hedeleg;
@@ -1788,8 +1829,12 @@ void riscv_cpu_do_interrupt(CPUState *cs)
         env->mtval = tval;
         env->mtval2 = mtval2;
         env->mtinst = tinst;
-        env->pc = (env->mtvec >> 2 << 2) +
-                  ((async && (env->mtvec & 3) == 1) ? cause * 4 : 0);
+        if (cpu->cfg.ext_smrnmi && nmi_execp) {
+            env->pc = env->rnmi_excpvec;
+        } else {
+            env->pc = (env->mtvec >> 2 << 2) +
+                      ((async && (env->mtvec & 3) == 1) ? cause * 4 : 0);
+        }
         riscv_cpu_set_mode(env, PRV_M);
     }
 
@@ -1802,6 +1847,8 @@ void riscv_cpu_do_interrupt(CPUState *cs)
 
     env->two_stage_lookup = false;
     env->two_stage_indirect_lookup = false;
+
+handled:
 #endif
     cs->exception_index = RISCV_EXCP_NONE; /* mark handled to qemu */
 }
-- 
2.31.1