[PATCH v2 1/3] target-i386: add a subsection for migrating vcpu's TSC rate

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

The newly added subsection 'vmstate_tsc_khz' is used by following
patches to migrate vcpu's TSC rate. For the back migration
compatibility, this subsection is not migrated on pc-*-2.4 and older
machine types by default. If users do want to migrate this subsection on
older machine types, they can enable it by giving a new cpu option
'save-tsc-freq'.

Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
---
 include/hw/i386/pc.h  |  5 +++++
 target-i386/cpu.c     |  1 +
 target-i386/cpu.h     |  2 ++
 target-i386/machine.c | 19 +++++++++++++++++++
 4 files changed, 27 insertions(+)

diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 0503485..7fde50f 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -300,6 +300,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
 #define PC_COMPAT_2_4 \
         HW_COMPAT_2_4 \
         {\
+            .driver   = TYPE_X86_CPU,\
+            .property = "save-tsc-freq",\
+            .value    = "off",\
+        },\
+        {\
             .driver   = "Haswell-" TYPE_X86_CPU,\
             .property = "abm",\
             .value    = "off",\
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 05d7f26..b6bb457 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -3143,6 +3143,7 @@ static Property x86_cpu_properties[] = {
     DEFINE_PROP_BOOL("check", X86CPU, check_cpuid, false),
     DEFINE_PROP_BOOL("enforce", X86CPU, enforce_cpuid, false),
     DEFINE_PROP_BOOL("kvm", X86CPU, expose_kvm, true),
+    DEFINE_PROP_BOOL("save-tsc-freq", X86CPU, env.save_tsc_khz, true),
     DEFINE_PROP_UINT32("level", X86CPU, env.cpuid_level, 0),
     DEFINE_PROP_UINT32("xlevel", X86CPU, env.cpuid_xlevel, 0),
     DEFINE_PROP_UINT32("xlevel2", X86CPU, env.cpuid_xlevel2, 0),
diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index 54d9d50..ba1a289 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -966,6 +966,8 @@ typedef struct CPUX86State {
     uint32_t sipi_vector;
     bool tsc_valid;
     int64_t tsc_khz;
+    int64_t tsc_khz_incoming;
+    bool save_tsc_khz;
     void *kvm_xsave_buf;
 
     uint64_t mcg_cap;
diff --git a/target-i386/machine.c b/target-i386/machine.c
index 9fa0563..7d68d63 100644
--- a/target-i386/machine.c
+++ b/target-i386/machine.c
@@ -752,6 +752,24 @@ static const VMStateDescription vmstate_xss = {
     }
 };
 
+static bool tsc_khz_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+    return env->tsc_khz_incoming && env->save_tsc_khz;
+}
+
+static const VMStateDescription vmstate_tsc_khz = {
+    .name = "cpu/tsc_khz",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = tsc_khz_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_INT64(env.tsc_khz_incoming, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 VMStateDescription vmstate_x86_cpu = {
     .name = "cpu",
     .version_id = 12,
@@ -871,6 +889,7 @@ VMStateDescription vmstate_x86_cpu = {
         &vmstate_msr_hyperv_crash,
         &vmstate_avx512,
         &vmstate_xss,
+        &vmstate_tsc_khz,
         NULL
     }
 };
-- 
2.4.8

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