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

Add a machine type pc-1.0-qemu-kvm for live migrate compatibility with qemu-kvm version 1.0. This 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-... 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. The existing pc-1.0 machine type is renamed to pc-1.0-qemu-git, with pc-1.0 becoming an alias for one or another, as selected by a configure option (defaulting to pc-1.0-qemu-git, IE no change). Two aproaches are taken: * In hw/timer/i8254_common.c, the VMSTATE_UINT32_TEST macro is used to test the version for the irq_disable flags, allowing version 3 or more, or version 2 for an inbound migrate from qemu-kvm (only). * In hw/acpi/piix4.c, qemu-kvm incorrectly uses version 2 for a version 3 structure, causing acpi_load_old to be used. acpi_load_old detects this situation based on the machine type and restarts the attempt to load the vmstate using a customised VMStateDescription. The above cleaner approach is unavailable here. 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. I have given this a moderate degree of testing but it could do with more. Note that certain hardware devices (including QXL) will not migrate properly due to a fundamental difference in their internal state between versions. Also note that (as expected) migration from qemu-2.x to qemu-1.0 will not work, even if the machine types are the same. Changes from v4 * Revert to using a machine type, but do not add alias machine types, configure options, or (potentially) change the meaning of pc-1.0 - leave this for distributions to ponder * Add compat_props for qemu-kvm-migration to the PIIX4_PM driver and the i8259 pit-common driver. Signed-off-by: Alex Bligh <alex(a)alex.org.uk&gt; --- hw/acpi/piix4.c | 26 +++++++++++++++++++++++--- hw/i386/pc_piix.c | 27 +++++++++++++++++++++++++++ hw/timer/i8254_common.c | 18 +++++++++++++++++- include/hw/i386/pc.h | 8 ++++++++ include/hw/timer/i8254_internal.h | 1 + 5 files changed, 76 insertions(+), 4 deletions(-) diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c index b72b34e..5c68d69 100644 --- a/hw/acpi/piix4.c +++ b/hw/acpi/piix4.c @@ -86,6 +86,8 @@ typedef struct PIIX4PMState { Notifier cpu_added_notifier; MemHotplugState acpi_memory_hotplug; + + bool qemu_kvm_migration; } PIIX4PMState; #define TYPE_PIIX4_PM "PIIX4_PM" @@ -200,12 +202,26 @@ static const VMStateDescription vmstate_pci_status = { } }; +static const VMStateDescription vmstate_acpi; + 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 && s->qemu_kvm_migration) { + VMStateDescription vmstate_acpi_compat = vmstate_acpi; + vmstate_acpi_compat.minimum_version_id = 2; + return vmstate_load_state(f, &vmstate_acpi_compat, + opaque, version_id); + } + ret = pci_device_load(PCI_DEVICE(s), f); if (ret < 0) { return ret; @@ -267,9 +283,11 @@ 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 - * qemu 1.2). + * 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; we can't do this all the time + * as using a minimum_version_id of 2 (rather than 3) would + * break migration from qemu-git 1.2. * */ static const VMStateDescription vmstate_acpi = { @@ -589,6 +607,8 @@ static Property piix4_pm_properties[] = { use_acpi_pci_hotplug, true), DEFINE_PROP_BOOL("memory-hotplug-support", PIIX4PMState, acpi_memory_hotplug.is_enabled, true), + DEFINE_PROP_BOOL("qemu-kvm-migration", PIIX4PMState, + qemu_kvm_migration, false), DEFINE_PROP_END_OF_LIST(), }; diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c index 7081c08..56555c1 100644 --- a/hw/i386/pc_piix.c +++ b/hw/i386/pc_piix.c @@ -644,6 +644,32 @@ 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),\ + },{\ + .driver = "pit-common",\ + .property = "qemu-kvm-migration",\ + .value = "on",\ + },{\ + .driver = "PIIX4_PM",\ + .property = "qemu-kvm-migration",\ + .value = "on",\ + } + +static QEMUMachine pc_machine_v1_0_qemu_kvm = { + PC_I440FX_1_2_MACHINE_OPTIONS, + .name = "pc-1.0-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 +912,7 @@ 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..7f3e4e3 100644 --- a/hw/timer/i8254_common.c +++ b/hw/timer/i8254_common.c @@ -257,6 +257,14 @@ static int pit_dispatch_post_load(void *opaque, int version_id) return 0; } +static bool has_irq_disabled(void *opaque, int version_id) +{ + PITCommonState *s = opaque; + return (version_id >= 3) || + (version_id == 2 && + s->qemu_kvm_migration); +} + static const VMStateDescription vmstate_pit_common = { .name = "i8254", .version_id = 3, @@ -266,7 +274,8 @@ 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, @@ -275,6 +284,12 @@ static const VMStateDescription vmstate_pit_common = { } }; +static Property pit_common_properties[] = { + DEFINE_PROP_BOOL("qemu-kvm-migration", PITCommonState, + qemu_kvm_migration, false), + DEFINE_PROP_END_OF_LIST(), +}; + static void pit_common_class_init(ObjectClass *klass, void *data) { DeviceClass *dc = DEVICE_CLASS(klass); @@ -287,6 +302,7 @@ static void pit_common_class_init(ObjectClass *klass, void *data) * done by board code. */ dc->cannot_instantiate_with_device_add_yet = true; + dc->props = pit_common_properties; } static const TypeInfo pit_common_type = { diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h index 1c0c382..e420dbc 100644 --- a/include/hw/i386/pc.h +++ b/include/hw/i386/pc.h @@ -346,6 +346,14 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *); .driver = "ioh3420",\ .property = COMPAT_PROP_PCP,\ .value = "off",\ + },{\ + .driver = "pit-common",\ + .property = "qemu-kvm-migration",\ + .value = "off",\ + },{\ + .driver = "PIIX4_PM",\ + .property = "qemu-kvm-migration",\ + .value = "off",\ } #define PC_COMPAT_1_7 \ diff --git a/include/hw/timer/i8254_internal.h b/include/hw/timer/i8254_internal.h index 61a1bfb..5f7ee36 100644 --- a/include/hw/timer/i8254_internal.h +++ b/include/hw/timer/i8254_internal.h @@ -55,6 +55,7 @@ typedef struct PITCommonState { MemoryRegion ioports; uint32_t iobase; PITChannelState channels[3]; + bool qemu_kvm_migration; } PITCommonState; #define TYPE_PIT_COMMON "pit-common" -- 1.7.9.5