[v5,2/2] target/loongarch: Implement lbt registers save/restore function

diff --git a/target/loongarch/cpu.h b/target/loongarch/cpu.h
index 2b3f2758f6..136866b7b8 100644
--- a/target/loongarch/cpu.h
+++ b/target/loongarch/cpu.h
@@ -286,6 +286,17 @@  enum loongarch_features {
     LOONGARCH_FEATURE_LBT, /* loongson binary translation extension */
 };
 
+typedef struct  LoongArchBT {
+    /* scratch registers */
+    uint64_t scr0;
+    uint64_t scr1;
+    uint64_t scr2;
+    uint64_t scr3;
+    /* loongarch eflags */
+    uint32_t eflags;
+    uint32_t ftop;
+} lbt_t;
+
 typedef struct CPUArchState {
     uint64_t gpr[32];
     uint64_t pc;
@@ -293,6 +304,7 @@  typedef struct CPUArchState {
     fpr_t fpr[32];
     bool cf[8];
     uint32_t fcsr0;
+    lbt_t  lbt;
 
     uint32_t cpucfg[21];
 
diff --git a/target/loongarch/kvm/kvm.c b/target/loongarch/kvm/kvm.c
index 8d2893efd3..5869e19f6d 100644
--- a/target/loongarch/kvm/kvm.c
+++ b/target/loongarch/kvm/kvm.c
@@ -477,6 +477,58 @@  static int kvm_loongarch_put_regs_fp(CPUState *cs)
     return ret;
 }
 
+static int kvm_loongarch_put_lbt(CPUState *cs)
+{
+    CPULoongArchState *env = cpu_env(cs);
+    uint64_t val;
+    int ret;
+
+    /* check whether vm support LBT firstly */
+    if (FIELD_EX32(env->cpucfg[2], CPUCFG2, LBT_ALL) != 7) {
+        return 0;
+    }
+
+    /* set six LBT registers including scr0-scr3, eflags, ftop */
+    ret = kvm_set_one_reg(cs, KVM_REG_LOONGARCH_LBT_SCR0, &env->lbt.scr0);
+    ret |= kvm_set_one_reg(cs, KVM_REG_LOONGARCH_LBT_SCR1, &env->lbt.scr1);
+    ret |= kvm_set_one_reg(cs, KVM_REG_LOONGARCH_LBT_SCR2, &env->lbt.scr2);
+    ret |= kvm_set_one_reg(cs, KVM_REG_LOONGARCH_LBT_SCR3, &env->lbt.scr3);
+    /*
+     * Be cautious, KVM_REG_LOONGARCH_LBT_FTOP is defined as 64-bit however
+     * lbt.ftop is 32-bit; the same with KVM_REG_LOONGARCH_LBT_EFLAGS register
+     */
+    val = env->lbt.eflags;
+    ret |= kvm_set_one_reg(cs, KVM_REG_LOONGARCH_LBT_EFLAGS, &val);
+    val = env->lbt.ftop;
+    ret |= kvm_set_one_reg(cs, KVM_REG_LOONGARCH_LBT_FTOP, &val);
+
+    return ret;
+}
+
+static int kvm_loongarch_get_lbt(CPUState *cs)
+{
+    CPULoongArchState *env = cpu_env(cs);
+    uint64_t val;
+    int ret;
+
+    /* check whether vm support LBT firstly */
+    if (FIELD_EX32(env->cpucfg[2], CPUCFG2, LBT_ALL) != 7) {
+        return 0;
+    }
+
+    /* get six LBT registers including scr0-scr3, eflags, ftop */
+    ret = kvm_get_one_reg(cs, KVM_REG_LOONGARCH_LBT_SCR0, &env->lbt.scr0);
+    ret |= kvm_get_one_reg(cs, KVM_REG_LOONGARCH_LBT_SCR1, &env->lbt.scr1);
+    ret |= kvm_get_one_reg(cs, KVM_REG_LOONGARCH_LBT_SCR2, &env->lbt.scr2);
+    ret |= kvm_get_one_reg(cs, KVM_REG_LOONGARCH_LBT_SCR3, &env->lbt.scr3);
+    ret |= kvm_get_one_reg(cs, KVM_REG_LOONGARCH_LBT_EFLAGS, &val);
+    env->lbt.eflags = (uint32_t)val;
+    ret |= kvm_get_one_reg(cs, KVM_REG_LOONGARCH_LBT_FTOP, &val);
+    env->lbt.ftop = (uint32_t)val;
+
+    return ret;
+}
+
 void kvm_arch_reset_vcpu(CPUState *cs)
 {
     CPULoongArchState *env = cpu_env(cs);
@@ -613,6 +665,11 @@  int kvm_arch_get_registers(CPUState *cs)
         return ret;
     }
 
+    ret = kvm_loongarch_get_lbt(cs);
+    if (ret) {
+        return ret;
+    }
+
     ret = kvm_loongarch_get_mpstate(cs);
     return ret;
 }
@@ -641,6 +698,11 @@  int kvm_arch_put_registers(CPUState *cs, int level)
         return ret;
     }
 
+    ret = kvm_loongarch_put_lbt(cs);
+    if (ret) {
+        return ret;
+    }
+
     ret = kvm_loongarch_put_mpstate(cs);
     return ret;
 }
diff --git a/target/loongarch/machine.c b/target/loongarch/machine.c
index 08a7fa5370..3d5c84ae9c 100644
--- a/target/loongarch/machine.c
+++ b/target/loongarch/machine.c
@@ -110,6 +110,29 @@  static const VMStateDescription vmstate_lasx = {
     },
 };
 
+static bool lbt_needed(void *opaque)
+{
+    LoongArchCPU *cpu = opaque;
+
+    return !!FIELD_EX64(cpu->env.cpucfg[2], CPUCFG2, LBT_ALL);
+}
+
+static const VMStateDescription vmstate_lbt = {
+    .name = "cpu/lbt",
+    .version_id = 0,
+    .minimum_version_id = 0,
+    .needed = lbt_needed,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT64(env.lbt.scr0,   LoongArchCPU),
+        VMSTATE_UINT64(env.lbt.scr1,   LoongArchCPU),
+        VMSTATE_UINT64(env.lbt.scr2,   LoongArchCPU),
+        VMSTATE_UINT64(env.lbt.scr3,   LoongArchCPU),
+        VMSTATE_UINT32(env.lbt.eflags, LoongArchCPU),
+        VMSTATE_UINT32(env.lbt.ftop,   LoongArchCPU),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
 #if defined(CONFIG_TCG) && !defined(CONFIG_USER_ONLY)
 static bool tlb_needed(void *opaque)
 {
@@ -219,6 +242,7 @@  const VMStateDescription vmstate_loongarch_cpu = {
 #if defined(CONFIG_TCG) && !defined(CONFIG_USER_ONLY)
         &vmstate_tlb,
 #endif
+        &vmstate_lbt,
         NULL
     }
 };