Re: [Qemu-stable] [PATCH v3] Fix pc migration from qemu <= 1.5

[Michael S. Tsirkin]

On Tue, Nov 05, 2013 at 06:46:27PM -0500, Cole Robinson wrote:
> The following commit introduced a migration incompatibility:
> 
> commit 568f0690fd9aa4d39d84b04c1a5dbb53a915c3fe
> Author: David Gibson <address@hidden>
> 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.
> 
> Cc: address@hidden
> Signed-off-by: Cole Robinson <address@hidden>

Reviewed-by: Michael S. Tsirkin <address@hidden>


BTW we really need unit tests for migration.


> ---
> 
> v3:
>     Don't regress -M pc-q35*
> 
>  hw/pci-host/piix.c        |  9 ++++++++-
>  hw/pci-host/q35.c         | 10 ++++++++--
>  include/hw/i386/pc.h      | 16 ++++++++++++++++
>  include/hw/pci-host/q35.h |  1 +
>  4 files changed, 33 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
> index bad3953..edc974e 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 */
> @@ -720,13 +721,19 @@ 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 b8feed1..c043998 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,
> @@ -124,6 +129,7 @@ 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 03cc0ba..57e8d16 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -260,6 +260,14 @@ int e820_add_entry(uint64_t, uint64_t, uint32_t);
>              .driver   = "qemu32-" TYPE_X86_CPU,\
>              .property = "model",\
>              .value    = stringify(3),\
> +        },{\
> +            .driver   = "i440FX-pcihost",\
> +            .property = "short_root_bus",\
> +            .value    = stringify(1),\
> +        },{\
> +            .driver   = "q35-pcihost",\
> +            .property = "short_root_bus",\
> +            .value    = stringify(1),\
>          }
>  
>  #define PC_COMPAT_1_5 \
> @@ -296,6 +304,14 @@ int e820_add_entry(uint64_t, uint64_t, uint32_t);
>              .driver = TYPE_X86_CPU,\
>              .property = "pmu",\
>              .value = "on",\
> +        },{\
> +            .driver   = "i440FX-pcihost",\
> +            .property = "short_root_bus",\
> +            .value    = stringify(0),\
> +        },{\
> +            .driver   = "q35-pcihost",\
> +            .property = "short_root_bus",\
> +            .value    = stringify(0),\
>          }
>  
>  #define PC_COMPAT_1_4 \
> diff --git a/include/hw/pci-host/q35.h b/include/hw/pci-host/q35.h
> index aee91aa..309065f 100644
> --- a/include/hw/pci-host/q35.h
> +++ b/include/hw/pci-host/q35.h
> @@ -61,6 +61,7 @@ typedef struct MCHPCIState {
>      ram_addr_t above_4g_mem_size;
>      uint64_t pci_hole64_size;
>      PcGuestInfo *guest_info;
> +    uint32_t short_root_bus;
>  } MCHPCIState;
>  
>  typedef struct Q35PCIHost {
> -- 
> 1.8.4.2