target/riscv: Split interrupt logic from riscv_cpu_update_mip.

This is to allow virtual interrupts to be inserted into S and VS
modes. Given virtual interrupts will be maintained in separate
mvip and hvip CSRs, riscv_cpu_update_mip will no longer be in the
path and interrupts need to be triggered for these cases from
rmw_hvip64 and rmw_mvip64 functions.

Signed-off-by: Rajnesh Kanwal <rkanwal@rivosinc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231016111736.28721-5-rkanwal@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/cpu.h

@@ -463,6 +463,7 @@ void riscv_cpu_swap_hypervisor_regs(CPURISCVState *env);
 int riscv_cpu_claim_interrupts(RISCVCPU *cpu, uint64_t interrupts);
 uint64_t riscv_cpu_update_mip(CPURISCVState *env, uint64_t mask,
                               uint64_t value);
+void riscv_cpu_interrupt(CPURISCVState *env);
 #define BOOL_TO_MASK(x) (-!!(x)) /* helper for riscv_cpu_update_mip value */
 void riscv_cpu_set_rdtime_fn(CPURISCVState *env, uint64_t (*fn)(void *),
                              void *arg);

target/riscv/cpu_helper.c

@@ -620,11 +620,12 @@ int riscv_cpu_claim_interrupts(RISCVCPU *cpu, uint64_t interrupts)
     }
 }
 
-uint64_t riscv_cpu_update_mip(CPURISCVState *env, uint64_t mask,
-                              uint64_t value)
+void riscv_cpu_interrupt(CPURISCVState *env)
 {
+    uint64_t gein, vsgein = 0, vstip = 0;
     CPUState *cs = env_cpu(env);
-    uint64_t gein, vsgein = 0, vstip = 0, old = env->mip;
+
+    QEMU_IOTHREAD_LOCK_GUARD();
 
     if (env->virt_enabled) {
         gein = get_field(env->hstatus, HSTATUS_VGEIN);
@@ -633,15 +634,25 @@ uint64_t riscv_cpu_update_mip(CPURISCVState *env, uint64_t mask,
 
     vstip = env->vstime_irq ? MIP_VSTIP : 0;
 
-    QEMU_IOTHREAD_LOCK_GUARD();
-
-    env->mip = (env->mip & ~mask) | (value & mask);
-
     if (env->mip | vsgein | vstip) {
         cpu_interrupt(cs, CPU_INTERRUPT_HARD);
     } else {
         cpu_reset_interrupt(cs, CPU_INTERRUPT_HARD);
     }
+}
+
+uint64_t riscv_cpu_update_mip(CPURISCVState *env, uint64_t mask, uint64_t value)
+{
+    uint64_t old = env->mip;
+
+    /* No need to update mip for VSTIP */
+    mask = ((mask == MIP_VSTIP) && env->vstime_irq) ? 0 : mask;
+
+    QEMU_IOTHREAD_LOCK_GUARD();
+
+    env->mip = (env->mip & ~mask) | (value & mask);
+
+    riscv_cpu_interrupt(env);
 
     return old;
 }