Re: [PATCH v4] target/riscv: Clearing the CSR values at reset and syncing the MPSTATE with the host

[Philippe Mathieu-Daudé]

Hi,

(old patch committed as 8633951530cc923f1e7a6cd250f670f24c0ed817)

On 13/9/23 11:13, liguang.zhang wrote:

From: "liguang.zhang" <liguang.zh...@hexintek.com>

Fix the guest reboot error 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.

v4 update:
rebase on riscv-to-apply

Signed-off-by: liguang.zhang <liguang.zh...@hexintek.com>
---
  target/riscv/kvm.c       | 42 ++++++++++++++++++++++++++++++++++++++++
  target/riscv/kvm_riscv.h |  1 +
  2 files changed, 43 insertions(+)

diff --git a/target/riscv/kvm.c b/target/riscv/kvm.c
index c01cfb03f4..8ee410b9b1 100644
--- a/target/riscv/kvm.c
+++ b/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)
  {
@@ -797,6 +799,24 @@ 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;
@@ -816,6 +836,18 @@ int kvm_arch_put_registers(CPUState *cs, int level)
          return ret;
      }

+ if (KVM_PUT_RESET_STATE == level) {

Why only RESET_STATE? Don't we also want that for FULL_STATE? IOW:

       if (level >= KVM_PUT_RESET_STATE) {

+        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;
  }

@@ -928,6 +960,7 @@ 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;
  }

@@ -1014,10 +1047,19 @@ void kvm_riscv_reset_vcpu(RISCVCPU *cpu)

      if (!kvm_enabled()) {
          return;
      }
+    for (int 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)

diff --git a/target/riscv/kvm_riscv.h b/target/riscv/kvm_riscv.h
index de8c209ebc..8f8c1f969a 100644
--- a/target/riscv/kvm_riscv.h
+++ b/target/riscv/kvm_riscv.h
@@ -27,5 +27,6 @@ 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