Re: [Qemu-devel] [PATCH] Fix pc migration from qemu <= 1.5

[Cole Robinson <crobinso@redhat.com>]

On 10/07/2013 05:43 PM, Bandan Das wrote:
> Hi Cole,
> 
> Cole Robinson <crobinso@redhat.com> writes:
> 
>> The following commit introduced a migration incompatibility:
>>
>> commit 568f0690fd9aa4d39d84b04c1a5dbb53a915c3fe
>> Author: David Gibson <david@gibson.dropbear.id.au>
>> Date:   Thu Jun 6 18:48:49 2013 +1000
>>
>>     pci: Replace pci_find_domain() with more general pci_root_bus_path()
>>
>> The issue is that i440fx savevm idstr went from 0000:00:00.0/I440FX to
>> 0000:00.0/I440FX. Unfortunately we are stuck with the breakage for
>> 1.6 machine types.
>>
>> Add a compat property to maintain the busted idstr for the 1.6 machine
>> types, but revert to the old style format for 1.7+, and <= 1.5.
>>
>> Tested with migration from qemu 1.5, qemu 1.6, and qemu.git.
>>
>> Signed-off-by: Cole Robinson <crobinso@redhat.com>
>> ---
>>  hw/i386/pc_piix.c         |  4 ++++
>>  hw/i386/pc_q35.c          |  4 ++++
>>  hw/pci-host/piix.c        |  9 ++++++++-
>>  hw/pci-host/q35.c         | 10 ++++++++--
>>  include/hw/i386/pc.h      | 28 ++++++++++++++++++++++++++++
>>  include/hw/pci-host/q35.h |  1 +
>>  6 files changed, 53 insertions(+), 3 deletions(-)
>>
>> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
>> index c6042c7..90f1ea4 100644
>> --- a/hw/i386/pc_piix.c
>> +++ b/hw/i386/pc_piix.c
>> @@ -346,6 +346,10 @@ static QEMUMachine pc_i440fx_machine_v1_7 = {
>>      .alias = "pc",
>>      .init = pc_init_pci,
>>      .is_default = 1,
>> +    .compat_props = (GlobalProperty[]) {
>> +        PC_COMPAT_1_7,
>> +        { /* end of list */ }
>> +    },
>>  };  
>>  #define PC_I440FX_1_6_MACHINE_OPTIONS PC_I440FX_MACHINE_OPTIONS
>> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
>> index ca84e1c..569f946 100644
>> --- a/hw/i386/pc_q35.c
>> +++ b/hw/i386/pc_q35.c
>> @@ -270,6 +270,10 @@ static QEMUMachine pc_q35_machine_v1_7 = {
>>      .name = "pc-q35-1.7",
>>      .alias = "q35",
>>      .init = pc_q35_init,
>> +    .compat_props = (GlobalProperty[]) {
>> +        PC_COMPAT_1_7,
>> +        { /* end of list */ }
>> +    },
>>  };
>>  #define PC_Q35_1_6_MACHINE_OPTIONS PC_Q35_MACHINE_OPTIONS
>> diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
>> index c041149..9dafe80 100644
>> --- a/hw/pci-host/piix.c
>> +++ b/hw/pci-host/piix.c
>> @@ -48,6 +48,7 @@ typedef struct I440FXState {
>>      PCIHostState parent_obj;
>>      PcPciInfo pci_info;
>>      uint64_t pci_hole64_size;
>> +    uint32_t short_root_bus;
>>  } I440FXState;
>>  
>>  #define PIIX_NUM_PIC_IRQS       16      /* i8259 * 2 */
>> @@ -712,13 +713,19 @@ static const TypeInfo i440fx_info = {
>>  static const char *i440fx_pcihost_root_bus_path(PCIHostState *host_bridge,
>>                                                  PCIBus *rootbus)
>>  {
>> +    I440FXState *s = I440FX_PCI_HOST_BRIDGE(host_bridge);
>> +
>>      /* For backwards compat with old device paths */
>> -    return "0000";
>> +    if (s->short_root_bus) {
>> +        return "0000";
>> +    }
>> +    return "0000:00";
>>  }
>>  
>>  static Property i440fx_props[] = {
>>      DEFINE_PROP_SIZE(PCI_HOST_PROP_PCI_HOLE64_SIZE, I440FXState,
>>                       pci_hole64_size, DEFAULT_PCI_HOLE64_SIZE),
>> +    DEFINE_PROP_UINT32("short_root_bus", I440FXState, short_root_bus, 0),
>>      DEFINE_PROP_END_OF_LIST(),
>>  };
>>  
>> diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
>> index ad703a4..cb3abfd 100644
>> --- a/hw/pci-host/q35.c
>> +++ b/hw/pci-host/q35.c
>> @@ -61,8 +61,13 @@ static void q35_host_realize(DeviceState *dev, Error **errp)
>>  static const char *q35_host_root_bus_path(PCIHostState *host_bridge,
>>                                            PCIBus *rootbus)
>>  {
>> -    /* For backwards compat with old device paths */
>> -    return "0000";
>> +    Q35PCIHost *s = Q35_HOST_DEVICE(host_bridge);
>> +
>> +     /* For backwards compat with old device paths */
>> +    if (s->mch.short_root_bus) {
>> +        return "0000";
>> +    }
>> +    return "0000:00";
>>  }
>>  
>>  static void q35_host_get_pci_hole_start(Object *obj, Visitor *v,
>> @@ -114,6 +119,7 @@ static Property mch_props[] = {
>>                          MCH_HOST_BRIDGE_PCIEXBAR_DEFAULT),
>>      DEFINE_PROP_SIZE(PCI_HOST_PROP_PCI_HOLE64_SIZE, Q35PCIHost,
>>                       mch.pci_hole64_size, DEFAULT_PCI_HOLE64_SIZE),
>> +    DEFINE_PROP_UINT32("short_root_bus", Q35PCIHost, mch.short_root_bus, 0),
>>      DEFINE_PROP_END_OF_LIST(),
>>  };
>>  
>> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
>> index 9b2ddc4..f9266f0 100644
>> --- a/include/hw/i386/pc.h
>> +++ b/include/hw/i386/pc.h
>> @@ -225,11 +225,31 @@ void pvpanic_init(ISABus *bus);
>>  
>>  int e820_add_entry(uint64_t, uint64_t, uint32_t);
>>  
>> +#define PC_COMPAT_1_7 \
>> +        {\
>> +            .driver   = "i440FX-pcihost",\
>> +            .property = "short_root_bus",\
>> +            .value    = stringify(0),\
>> +        },{\
>> +            .driver   = "mch",\
>> +            .property = "short_root_bus",\
>> +            .value    = stringify(0),\
>> +        }
>> +
> 
> This is probably not needed since the default value of 
> short_root_bus is already 0. BTW, 1_7 shouldn't have 
> compat props since  it's already the most uptodate 
> machine type and by definition, compat properties only apply
> to older machine types.
> 

Yeah I got confused here, I'll fix and resend.

- Cole