target/loongarch: Add steal time support on migration

With pv steal time supported, VM machine needs get physical address
of each vcpu and notify new host during migration. Here two
functions kvm_get_stealtime/kvm_set_stealtime, and guest steal time
physical address is only updated on KVM_PUT_FULL_STATE stage.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Reviewed-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20240930064040.753929-1-maobibo@loongson.cn>
Signed-off-by: Song Gao <gaosong@loongson.cn>

target/loongarch/cpu.h

@@ -364,6 +364,9 @@ typedef struct CPUArchState {
     uint64_t CSR_DBG;
     uint64_t CSR_DERA;
     uint64_t CSR_DSAVE;
+    struct {
+        uint64_t guest_addr;
+    } stealtime;
 
 #ifdef CONFIG_TCG
     float_status fp_status;

target/loongarch/kvm/kvm.c

@@ -34,6 +34,55 @@ const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
     KVM_CAP_LAST_INFO
 };
 
+static int kvm_get_stealtime(CPUState *cs)
+{
+    CPULoongArchState *env = cpu_env(cs);
+    int err;
+    struct kvm_device_attr attr = {
+        .group = KVM_LOONGARCH_VCPU_PVTIME_CTRL,
+        .attr = KVM_LOONGARCH_VCPU_PVTIME_GPA,
+        .addr = (uint64_t)&env->stealtime.guest_addr,
+    };
+
+    err = kvm_vcpu_ioctl(cs, KVM_HAS_DEVICE_ATTR, attr);
+    if (err) {
+        return 0;
+    }
+
+    err = kvm_vcpu_ioctl(cs, KVM_GET_DEVICE_ATTR, attr);
+    if (err) {
+        error_report("PVTIME: KVM_GET_DEVICE_ATTR: %s", strerror(errno));
+        return err;
+    }
+
+    return 0;
+}
+
+static int kvm_set_stealtime(CPUState *cs)
+{
+    CPULoongArchState *env = cpu_env(cs);
+    int err;
+    struct kvm_device_attr attr = {
+        .group = KVM_LOONGARCH_VCPU_PVTIME_CTRL,
+        .attr = KVM_LOONGARCH_VCPU_PVTIME_GPA,
+        .addr = (uint64_t)&env->stealtime.guest_addr,
+    };
+
+    err = kvm_vcpu_ioctl(cs, KVM_HAS_DEVICE_ATTR, attr);
+    if (err) {
+        return 0;
+    }
+
+    err = kvm_vcpu_ioctl(cs, KVM_SET_DEVICE_ATTR, attr);
+    if (err) {
+        error_report("PVTIME: KVM_SET_DEVICE_ATTR %s with gpa "TARGET_FMT_lx,
+                      strerror(errno), env->stealtime.guest_addr);
+        return err;
+    }
+
+    return 0;
+}
+
 static int kvm_loongarch_get_regs_core(CPUState *cs)
 {
     int ret = 0;
@@ -670,6 +719,11 @@ int kvm_arch_get_registers(CPUState *cs, Error **errp)
         return ret;
     }
 
+    ret = kvm_get_stealtime(cs);
+    if (ret) {
+        return ret;
+    }
+
     ret = kvm_loongarch_get_mpstate(cs);
     return ret;
 }
@@ -703,6 +757,17 @@ int kvm_arch_put_registers(CPUState *cs, int level, Error **errp)
         return ret;
     }
 
+    if (level >= KVM_PUT_FULL_STATE) {
+        /*
+         * only KVM_PUT_FULL_STATE is required, kvm kernel will clear
+         * guest_addr for KVM_PUT_RESET_STATE
+         */
+        ret = kvm_set_stealtime(cs);
+        if (ret) {
+            return ret;
+        }
+    }
+
     ret = kvm_loongarch_put_mpstate(cs);
     return ret;
 }

target/loongarch/machine.c

@@ -168,8 +168,8 @@ static const VMStateDescription vmstate_tlb = {
 /* LoongArch CPU state */
 const VMStateDescription vmstate_loongarch_cpu = {
     .name = "cpu",
-    .version_id = 2,
+    .version_id = 3,
-    .minimum_version_id = 2,
+    .minimum_version_id = 3,
     .fields = (const VMStateField[]) {
         VMSTATE_UINTTL_ARRAY(env.gpr, LoongArchCPU, 32),
         VMSTATE_UINTTL(env.pc, LoongArchCPU),
@@ -232,6 +232,8 @@ const VMStateDescription vmstate_loongarch_cpu = {
         VMSTATE_UINT64(env.CSR_DSAVE, LoongArchCPU),
 
         VMSTATE_UINT64(kvm_state_counter, LoongArchCPU),
+        /* PV steal time */
+        VMSTATE_UINT64(env.stealtime.guest_addr, LoongArchCPU),
 
         VMSTATE_END_OF_LIST()
     },