[Qemu-devel] [PATCH v3 1/2] Add machine type pc-1.0-qemu-kvm for live migrate compatibility with qemu-kvm

[Alex Bligh <alex@alex.org.uk>]

Add a machine type pc-1.0-qemu-kvm for live migrate compatibility
with qemu-kvm version 1.0.

Signed-off-by: Alex Bligh <alex@alex.org.uk>
---
 hw/acpi/piix4.c         |   47 +++++++++++++++++++++++++++++++++++++++++++++--
 hw/i386/pc_piix.c       |   30 ++++++++++++++++++++++++++++++
 hw/timer/i8254_common.c |   10 +++++++++-
 3 files changed, 84 insertions(+), 3 deletions(-)

diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
index b72b34e..e016005 100644
--- a/hw/acpi/piix4.c
+++ b/hw/acpi/piix4.c
@@ -37,6 +37,8 @@
 #include "hw/acpi/memory_hotplug.h"
 #include "hw/acpi/acpi_dev_interface.h"
 
+extern int qemu_kvm_1_0_compat;
+
 //#define DEBUG
 
 #ifdef DEBUG
@@ -200,12 +202,24 @@ static const VMStateDescription vmstate_pci_status = {
     }
 };
 
+static const VMStateDescription vmstate_acpi_compat;
+
 static int acpi_load_old(QEMUFile *f, void *opaque, int version_id)
 {
     PIIX4PMState *s = opaque;
     int ret, i;
     uint16_t temp;
 
+    /* If we are expecting the inbound migration to come from
+     * qemu-kvm 1.0, it will have a version_id of 2 but really
+     * be version 3, so call back the original vmstate_load_state
+     * with a different more tolerant vmstate descriptor
+     */
+    if ((version_id == 2) && (qemu_kvm_1_0_compat)) {
+        return vmstate_load_state(f, &vmstate_acpi_compat,
+                                  opaque, version_id);
+    }
+
     ret = pci_device_load(PCI_DEVICE(s), f);
     if (ret < 0) {
         return ret;
@@ -267,8 +281,9 @@ static const VMStateDescription vmstate_memhp_state = {
 };
 
 /* qemu-kvm 1.2 uses version 3 but advertised as 2
- * To support incoming qemu-kvm 1.2 migration, change version_id
- * and minimum_version_id to 2 below (which breaks migration from
+ * To support incoming qemu-kvm 1.2 migration, we support
+ * via a command line option a change to minimum_version_id
+ * of 2 in a _compat structure (which breaks migration from
  * qemu 1.2).
  *
  */
@@ -307,6 +322,34 @@ static const VMStateDescription vmstate_acpi = {
     }
 };
 
+static const VMStateDescription vmstate_acpi_compat = {
+    .name = "piix4_pm",
+    .version_id = 3,
+    .minimum_version_id = 2,
+    .minimum_version_id_old = 1,
+    .load_state_old = NULL, /* to avoid recursion */
+    .post_load = vmstate_acpi_post_load,
+    .fields      = (VMStateField[]) {
+        VMSTATE_PCI_DEVICE(parent_obj, PIIX4PMState),
+        VMSTATE_UINT16(ar.pm1.evt.sts, PIIX4PMState),
+        VMSTATE_UINT16(ar.pm1.evt.en, PIIX4PMState),
+        VMSTATE_UINT16(ar.pm1.cnt.cnt, PIIX4PMState),
+        VMSTATE_STRUCT(apm, PIIX4PMState, 0, vmstate_apm, APMState),
+        VMSTATE_TIMER(ar.tmr.timer, PIIX4PMState),
+        VMSTATE_INT64(ar.tmr.overflow_time, PIIX4PMState),
+        VMSTATE_STRUCT(ar.gpe, PIIX4PMState, 2, vmstate_gpe, ACPIGPE),
+        VMSTATE_STRUCT_TEST(
+            acpi_pci_hotplug.acpi_pcihp_pci_status[ACPI_PCIHP_BSEL_DEFAULT],
+            PIIX4PMState,
+            vmstate_test_no_use_acpi_pci_hotplug,
+            2, vmstate_pci_status,
+            struct AcpiPciHpPciStatus),
+        VMSTATE_PCI_HOTPLUG(acpi_pci_hotplug, PIIX4PMState,
+                            vmstate_test_use_acpi_pci_hotplug),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static void piix4_reset(void *opaque)
 {
     PIIX4PMState *s = opaque;
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 7081c08..48a4942 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -70,6 +70,8 @@ static bool smbios_legacy_mode;
 static bool gigabyte_align = true;
 static bool has_reserved_memory = true;
 
+int qemu_kvm_1_0_compat;
+
 /* PC hardware initialisation */
 static void pc_init1(MachineState *machine,
                      int pci_enabled,
@@ -386,6 +388,14 @@ static void pc_init_pci_1_2(MachineState *machine)
     pc_init_pci(machine);
 }
 
+/* PC machine init function for qemu-kvm 1.0 */
+static void pc_init_pci_1_2_qemu_kvm(MachineState *machine)
+{
+    qemu_kvm_1_0_compat = 1;
+    pc_compat_1_2(machine);
+    pc_init_pci(machine);
+}
+
 /* PC init function for pc-0.10 to pc-0.13 */
 static void pc_init_pci_no_kvmclock(MachineState *machine)
 {
@@ -644,6 +654,25 @@ static QEMUMachine pc_machine_v1_0 = {
     .hw_version = "1.0",
 };
 
+#define PC_COMPAT_1_0_QEMU_KVM \
+        PC_COMPAT_1_0,\
+        {\
+            .driver   = "cirrus-vga",\
+            .property = "vgamem_mb",\
+            .value    = stringify(16),\
+        }
+
+static QEMUMachine pc_machine_v1_0_qemu_kvm = {
+    PC_I440FX_1_2_MACHINE_OPTIONS,
+    .name = "pc-1.0-qemu-kvm",
+    .init = pc_init_pci_1_2_qemu_kvm,
+    .compat_props = (GlobalProperty[]) {
+        PC_COMPAT_1_0_QEMU_KVM,
+        { /* end of list */ }
+    },
+    .hw_version = "1.0",
+};
+
 #define PC_COMPAT_0_15 \
         PC_COMPAT_1_0
 
@@ -886,6 +915,7 @@ static void pc_machine_init(void)
     qemu_register_pc_machine(&pc_machine_v1_2);
     qemu_register_pc_machine(&pc_machine_v1_1);
     qemu_register_pc_machine(&pc_machine_v1_0);
+    qemu_register_pc_machine(&pc_machine_v1_0_qemu_kvm);
     qemu_register_pc_machine(&pc_machine_v0_15);
     qemu_register_pc_machine(&pc_machine_v0_14);
     qemu_register_pc_machine(&pc_machine_v0_13);
diff --git a/hw/timer/i8254_common.c b/hw/timer/i8254_common.c
index 07345f6..b4deead 100644
--- a/hw/timer/i8254_common.c
+++ b/hw/timer/i8254_common.c
@@ -29,6 +29,8 @@
 #include "hw/timer/i8254.h"
 #include "hw/timer/i8254_internal.h"
 
+extern int qemu_kvm_1_0_compat;
+
 /* val must be 0 or 1 */
 void pit_set_gate(ISADevice *dev, int channel, int val)
 {
@@ -257,6 +259,11 @@ static int pit_dispatch_post_load(void *opaque, int version_id)
     return 0;
 }
 
+static bool has_irq_disabled(void *opaque, int version_id)
+{
+    return (version_id >= 3) || ((version_id == 2) && qemu_kvm_1_0_compat);
+}
+
 static const VMStateDescription vmstate_pit_common = {
     .name = "i8254",
     .version_id = 3,
@@ -266,7 +273,8 @@ static const VMStateDescription vmstate_pit_common = {
     .pre_save = pit_dispatch_pre_save,
     .post_load = pit_dispatch_post_load,
     .fields = (VMStateField[]) {
-        VMSTATE_UINT32_V(channels[0].irq_disabled, PITCommonState, 3),
+        VMSTATE_UINT32_TEST(channels[0].irq_disabled, PITCommonState,
+                            has_irq_disabled),
         VMSTATE_STRUCT_ARRAY(channels, PITCommonState, 3, 2,
                              vmstate_pit_channel, PITChannelState),
         VMSTATE_INT64(channels[0].next_transition_time,
-- 
1.7.9.5