Re: [Qemu-devel] [PATCH] [RFC] Add machine type pc-1.0-qemu-kvm for live migrate compatibility with qemu-kvm

[Alex Bligh]

ping: anyone got any views on this one?

On 22 Jul 2014, at 19:43, Alex Bligh <address@hidden> wrote:

> Add a machine type pc-1.0-qemu-kvm for live migrate compatibility
> with qemu-kvm version 1.0.
> 
> Signed-off-by: Alex Bligh <address@hidden>
> ---
> hw/acpi/piix4.c          |   49 ++++++++++++++++++++++++++++++++++++++++++++--
> hw/i386/pc_piix.c        |   31 +++++++++++++++++++++++++++++
> hw/timer/i8254_common.c  |   41 ++++++++++++++++++++++++++++++++++++++
> include/hw/acpi/piix4.h  |    1 +
> include/hw/timer/i8254.h |    2 ++
> 5 files changed, 122 insertions(+), 2 deletions(-)
> 
> This RFC patch adds inbound migrate capability from qemu-kvm version
> 1.0. The main ideas are those set out in Cole Robinson's patch here:
> http://pkgs.fedoraproject.org/cgit/qemu.git/tree/0001-Fix-migration-from-qemu-kvm.patch?h=f20
> however, rather than patching statically (and breaking inbound
> migration on existing machine types), I have added a new machine
> type (pc-1.0-qemu-kvm) without affecting any other machine types.
> 
> This requires 'hot patching' the VMStateDescription in a couple of
> places, which in turn is less than obvious as there may be (indeed
> are for i8259) derived classes. Whilst pretty nausea-inducing, this
> approach has the benefit of being entirely self-contained.
> 
> I developed this on qemu 2.0 but have forward ported it (trivially)
> to master. My testing has been on a VM live-migrated-to-file from
> Ubuntu Precise qemu-kvm 1.0. Testing has been light to date (i.e.
> can I migrate it inbound with -S without anything complaining).
> 
> I have not (yet) brought forward the qxl rom size (and possibly
> video ram) changes in Cole's patches as I'd prefer an assessment
> of whether this is the right approach first.
> 
> diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
> index b72b34e..708db79 100644
> --- a/hw/acpi/piix4.c
> +++ b/hw/acpi/piix4.c
> @@ -267,8 +267,9 @@ 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 +308,34 @@ 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 = acpi_load_old,
> +    .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;
> @@ -619,6 +648,22 @@ static void piix4_pm_class_init(ObjectClass *klass, void 
> *data)
>     adevc->ospm_status = piix4_ospm_status;
> }
> 
> +void piix4_pm_class_fix_compat(void)
> +{
> +    GSList *el, *devices = object_class_get_list(TYPE_DEVICE, false);
> +    /*
> +     * Change the vmstate field in this class and any derived classes
> +     * if not overriden. As no other classes should be using this
> +     * vmstate, we can simply iterate the class list
> +     */
> +    for (el = devices; el; el = el->next) {
> +        DeviceClass *dc = el->data;
> +        if (dc->vmsd == &vmstate_acpi) {
> +            dc->vmsd = &vmstate_acpi_compat;
> +        }
> +    }
> +}
> +
> static const TypeInfo piix4_pm_info = {
>     .name          = TYPE_PIIX4_PM,
>     .parent        = TYPE_PCI_DEVICE,
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index 7081c08..e400ea6 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -49,6 +49,8 @@
> #include "hw/acpi/acpi.h"
> #include "cpu.h"
> #include "qemu/error-report.h"
> +#include "hw/acpi/piix4.h"
> +#include "hw/timer/i8254.h"
> #ifdef CONFIG_XEN
> #  include <xen/hvm/hvm_info_table.h>
> #endif
> @@ -386,6 +388,15 @@ 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)
> +{
> +    piix4_pm_class_fix_compat();
> +    pit_common_class_fix_compat();
> +    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 +655,25 @@ 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 +916,7 @@ 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..511ea05 100644
> --- a/hw/timer/i8254_common.c
> +++ b/hw/timer/i8254_common.c
> @@ -275,6 +275,29 @@ static const VMStateDescription vmstate_pit_common = {
>     }
> };
> 
> +static const VMStateDescription vmstate_pit_common_compat = {
> +    .name = "i8254",
> +    .version_id = 3,
> +    .minimum_version_id = 2,
> +    .minimum_version_id_old = 1,
> +    .load_state_old = pit_load_old,
> +    .pre_save = pit_dispatch_pre_save,
> +    .post_load = pit_dispatch_post_load,
> +    .fields = (VMStateField[]) {
> +        /* qemu-kvm version_id=2 had 'flags' here which is equivalent
> +         * This fixes incoming migration from qemu-kvm 1.0, but breaks
> +         * incoming migration from qemu < 1.1
> +         */
> +        /* VMSTATE_UINT32_V(channels[0].irq_disabled, PITCommonState, 3), */
> +        VMSTATE_UINT32(channels[0].irq_disabled, PITCommonState),
> +        VMSTATE_STRUCT_ARRAY(channels, PITCommonState, 3, 2,
> +                             vmstate_pit_channel, PITChannelState),
> +        VMSTATE_INT64(channels[0].next_transition_time,
> +                      PITCommonState), /* formerly irq_timer */
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> static void pit_common_class_init(ObjectClass *klass, void *data)
> {
>     DeviceClass *dc = DEVICE_CLASS(klass);
> @@ -289,6 +312,24 @@ static void pit_common_class_init(ObjectClass *klass, 
> void *data)
>     dc->cannot_instantiate_with_device_add_yet = true;
> }
> 
> +void pit_common_class_fix_compat(void)
> +{
> +    GSList *el, *devices = object_class_get_list(TYPE_DEVICE, false);
> +    /*
> +     * Change the vmstate field in this class and any derived classes
> +     * if not overriden. As no other classes should be using this
> +     * vmstate, we can simply iterate the class list
> +     */
> +    for (el = devices; el; el = el->next) {
> +        DeviceClass *dc = el->data;
> +        if (dc->vmsd == &vmstate_pit_common) {
> +            dc->vmsd = &vmstate_pit_common_compat;
> +        }
> +    }
> +
> +    g_slist_free(devices);
> +}
> +
> static const TypeInfo pit_common_type = {
>     .name          = TYPE_PIT_COMMON,
>     .parent        = TYPE_ISA_DEVICE,
> diff --git a/include/hw/acpi/piix4.h b/include/hw/acpi/piix4.h
> index 65e6fd7..811d88f 100644
> --- a/include/hw/acpi/piix4.h
> +++ b/include/hw/acpi/piix4.h
> @@ -4,5 +4,6 @@
> #include "qemu/typedefs.h"
> 
> Object *piix4_pm_find(void);
> +void piix4_pm_class_fix_compat(void);
> 
> #endif
> diff --git a/include/hw/timer/i8254.h b/include/hw/timer/i8254.h
> index 4349033..0126424 100644
> --- a/include/hw/timer/i8254.h
> +++ b/include/hw/timer/i8254.h
> @@ -72,4 +72,6 @@ static inline ISADevice *kvm_pit_init(ISABus *bus, int base)
> void pit_set_gate(ISADevice *dev, int channel, int val);
> void pit_get_channel_info(ISADevice *dev, int channel, PITChannelInfo *info);
> 
> +void pit_common_class_fix_compat(void);
> +
> #endif /* !HW_I8254_H */
> -- 
> 1.7.9.5
> 
> 
> 

-- 
Alex Bligh