target/riscv: Clear CSR values at reset and sync MPSTATE with host

This patch fixes guest reboot errors when using KVM.

There are two issues when rebooting a guest using KVM
1. When the guest initiates a reboot the host is unable to stop the vcpu
2. When running a SMP guest the qemu monitor system_reset causes a vcpu crash

This can be fixed by clearing the CSR values at reset and syncing the
MPSTATE with the host.

Signed-off-by: liguang.zhang <liguang.zhang@hexintek.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20230913091332.17355-1-18622748025@163.com>
[ Changes by AF
 - Fixup commit message
 - Fixup patch style
]
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/kvm.c

@@ -51,6 +51,8 @@ void riscv_kvm_aplic_request(void *opaque, int irq, int level)
     kvm_set_irq(kvm_state, irq, !!level);
 }
 
+static bool cap_has_mp_state;
+
 static uint64_t kvm_riscv_reg_id(CPURISCVState *env, uint64_t type,
                                  uint64_t idx)
 {
@@ -795,6 +797,24 @@ int kvm_arch_get_registers(CPUState *cs)
     return ret;
 }
 
+int kvm_riscv_sync_mpstate_to_kvm(RISCVCPU *cpu, int state)
+{
+    if (cap_has_mp_state) {
+        struct kvm_mp_state mp_state = {
+            .mp_state = state
+        };
+
+        int ret = kvm_vcpu_ioctl(CPU(cpu), KVM_SET_MP_STATE, &mp_state);
+        if (ret) {
+            fprintf(stderr, "%s: failed to sync MP_STATE %d/%s\n",
+                    __func__, ret, strerror(-ret));
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
 int kvm_arch_put_registers(CPUState *cs, int level)
 {
     int ret = 0;
@@ -814,6 +834,18 @@ int kvm_arch_put_registers(CPUState *cs, int level)
         return ret;
     }
 
+    if (KVM_PUT_RESET_STATE == level) {
+        RISCVCPU *cpu = RISCV_CPU(cs);
+        if (cs->cpu_index == 0) {
+            ret = kvm_riscv_sync_mpstate_to_kvm(cpu, KVM_MP_STATE_RUNNABLE);
+        } else {
+            ret = kvm_riscv_sync_mpstate_to_kvm(cpu, KVM_MP_STATE_STOPPED);
+        }
+        if (ret) {
+            return ret;
+        }
+    }
+
     return ret;
 }
 
@@ -926,6 +958,7 @@ int kvm_arch_get_default_type(MachineState *ms)
 
 int kvm_arch_init(MachineState *ms, KVMState *s)
 {
+    cap_has_mp_state = kvm_check_extension(s, KVM_CAP_MP_STATE);
     return 0;
 }
 
@@ -1008,14 +1041,25 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
 void kvm_riscv_reset_vcpu(RISCVCPU *cpu)
 {
     CPURISCVState *env = &cpu->env;
+    int i;
 
     if (!kvm_enabled()) {
         return;
     }
+    for (i = 0; i < 32; i++) {
+        env->gpr[i] = 0;
+    }
     env->pc = cpu->env.kernel_addr;
     env->gpr[10] = kvm_arch_vcpu_id(CPU(cpu)); /* a0 */
     env->gpr[11] = cpu->env.fdt_addr;          /* a1 */
     env->satp = 0;
+    env->mie = 0;
+    env->stvec = 0;
+    env->sscratch = 0;
+    env->sepc = 0;
+    env->scause = 0;
+    env->stval = 0;
+    env->mip = 0;
 }
 
 void kvm_riscv_set_irq(RISCVCPU *cpu, int irq, int level)

target/riscv/kvm_riscv.h

@@ -30,5 +30,6 @@ void kvm_riscv_aia_create(MachineState *machine, uint64_t group_shift,
                           uint64_t aplic_base, uint64_t imsic_base,
                           uint64_t guest_num);
 void riscv_kvm_aplic_request(void *opaque, int irq, int level);
+int kvm_riscv_sync_mpstate_to_kvm(RISCVCPU *cpu, int state);
 
 #endif