target/riscv: Combine set_mode and set_virt functions.

Combining riscv_cpu_set_virt_enabled() and riscv_cpu_set_mode()
functions. This is to make complete mode change information
available through a single function.

This allows to easily differentiate between HS->VS, VS->HS
and VS->VS transitions when executing state update codes.
For example: One use-case which inspired this change is
to update mode-specific instruction and cycle counters
which requires information of both prev mode and current
mode.

Signed-off-by: Rajnesh Kanwal <rkanwal@rivosinc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20240711-smcntrpmf_v7-v8-1-b7c38ae7b263@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/cpu.h

@@ -567,7 +567,7 @@ void riscv_cpu_set_aia_ireg_rmw_fn(CPURISCVState *env, uint32_t priv,
 RISCVException smstateen_acc_ok(CPURISCVState *env, int index, uint64_t bit);
 #endif /* !CONFIG_USER_ONLY */
 
-void riscv_cpu_set_mode(CPURISCVState *env, target_ulong newpriv);
+void riscv_cpu_set_mode(CPURISCVState *env, target_ulong newpriv, bool virt_en);
 
 void riscv_translate_init(void);
 G_NORETURN void riscv_raise_exception(CPURISCVState *env,

target/riscv/cpu_helper.c

@@ -619,30 +619,6 @@ void riscv_cpu_set_geilen(CPURISCVState *env, target_ulong geilen)
     env->geilen = geilen;
 }
 
-/* This function can only be called to set virt when RVH is enabled */
-void riscv_cpu_set_virt_enabled(CPURISCVState *env, bool enable)
-{
-    /* Flush the TLB on all virt mode changes. */
-    if (env->virt_enabled != enable) {
-        tlb_flush(env_cpu(env));
-    }
-
-    env->virt_enabled = enable;
-
-    if (enable) {
-        /*
-         * The guest external interrupts from an interrupt controller are
-         * delivered only when the Guest/VM is running (i.e. V=1). This means
-         * any guest external interrupt which is triggered while the Guest/VM
-         * is not running (i.e. V=0) will be missed on QEMU resulting in guest
-         * with sluggish response to serial console input and other I/O events.
-         *
-         * To solve this, we check and inject interrupt after setting V=1.
-         */
-        riscv_cpu_update_mip(env, 0, 0);
-    }
-}
-
 int riscv_cpu_claim_interrupts(RISCVCPU *cpu, uint64_t interrupts)
 {
     CPURISCVState *env = &cpu->env;
@@ -715,7 +691,7 @@ void riscv_cpu_set_aia_ireg_rmw_fn(CPURISCVState *env, uint32_t priv,
     }
 }
 
-void riscv_cpu_set_mode(CPURISCVState *env, target_ulong newpriv)
+void riscv_cpu_set_mode(CPURISCVState *env, target_ulong newpriv, bool virt_en)
 {
     g_assert(newpriv <= PRV_M && newpriv != PRV_RESERVED);
 
@@ -736,6 +712,28 @@ void riscv_cpu_set_mode(CPURISCVState *env, target_ulong newpriv)
      * preemptive context switch. As a result, do both.
      */
     env->load_res = -1;
+
+    if (riscv_has_ext(env, RVH)) {
+        /* Flush the TLB on all virt mode changes. */
+        if (env->virt_enabled != virt_en) {
+            tlb_flush(env_cpu(env));
+        }
+
+        env->virt_enabled = virt_en;
+        if (virt_en) {
+            /*
+             * The guest external interrupts from an interrupt controller are
+             * delivered only when the Guest/VM is running (i.e. V=1). This
+             * means any guest external interrupt which is triggered while the
+             * Guest/VM is not running (i.e. V=0) will be missed on QEMU
+             * resulting in guest with sluggish response to serial console
+             * input and other I/O events.
+             *
+             * To solve this, we check and inject interrupt after setting V=1.
+             */
+            riscv_cpu_update_mip(env, 0, 0);
+        }
+    }
 }
 
 /*
@@ -1648,6 +1646,7 @@ void riscv_cpu_do_interrupt(CPUState *cs)
 {
     RISCVCPU *cpu = RISCV_CPU(cs);
     CPURISCVState *env = &cpu->env;
+    bool virt = env->virt_enabled;
     bool write_gva = false;
     uint64_t s;
 
@@ -1778,7 +1777,7 @@ void riscv_cpu_do_interrupt(CPUState *cs)
 
                 htval = env->guest_phys_fault_addr;
 
-                riscv_cpu_set_virt_enabled(env, 0);
+                virt = false;
             } else {
                 /* Trap into HS mode */
                 env->hstatus = set_field(env->hstatus, HSTATUS_SPV, false);
@@ -1799,7 +1798,7 @@ void riscv_cpu_do_interrupt(CPUState *cs)
         env->htinst = tinst;
         env->pc = (env->stvec >> 2 << 2) +
                   ((async && (env->stvec & 3) == 1) ? cause * 4 : 0);
-        riscv_cpu_set_mode(env, PRV_S);
+        riscv_cpu_set_mode(env, PRV_S, virt);
     } else {
         /* handle the trap in M-mode */
         if (riscv_has_ext(env, RVH)) {
@@ -1815,7 +1814,7 @@ void riscv_cpu_do_interrupt(CPUState *cs)
             mtval2 = env->guest_phys_fault_addr;
 
             /* Trapping to M mode, virt is disabled */
-            riscv_cpu_set_virt_enabled(env, 0);
+            virt = false;
         }
 
         s = env->mstatus;
@@ -1830,7 +1829,7 @@ void riscv_cpu_do_interrupt(CPUState *cs)
         env->mtinst = tinst;
         env->pc = (env->mtvec >> 2 << 2) +
                   ((async && (env->mtvec & 3) == 1) ? cause * 4 : 0);
-        riscv_cpu_set_mode(env, PRV_M);
+        riscv_cpu_set_mode(env, PRV_M, virt);
     }
 
     /*

target/riscv/op_helper.c

@@ -264,7 +264,7 @@ void helper_cbo_inval(CPURISCVState *env, target_ulong address)
 target_ulong helper_sret(CPURISCVState *env)
 {
     uint64_t mstatus;
-    target_ulong prev_priv, prev_virt;
+    target_ulong prev_priv, prev_virt = env->virt_enabled;
 
     if (!(env->priv >= PRV_S)) {
         riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
@@ -307,11 +307,9 @@ target_ulong helper_sret(CPURISCVState *env)
         if (prev_virt) {
             riscv_cpu_swap_hypervisor_regs(env);
         }
-
-        riscv_cpu_set_virt_enabled(env, prev_virt);
     }
 
-    riscv_cpu_set_mode(env, prev_priv);
+    riscv_cpu_set_mode(env, prev_priv, prev_virt);
 
     return retpc;
 }
@@ -347,16 +345,13 @@ target_ulong helper_mret(CPURISCVState *env)
         mstatus = set_field(mstatus, MSTATUS_MPRV, 0);
     }
     env->mstatus = mstatus;
-    riscv_cpu_set_mode(env, prev_priv);
 
-    if (riscv_has_ext(env, RVH)) {
+    if (riscv_has_ext(env, RVH) && prev_virt) {
-        if (prev_virt) {
+        riscv_cpu_swap_hypervisor_regs(env);
-            riscv_cpu_swap_hypervisor_regs(env);
-        }
-
-        riscv_cpu_set_virt_enabled(env, prev_virt);
     }
 
+    riscv_cpu_set_mode(env, prev_priv, prev_virt);
+
     return retpc;
 }