Re: [Qemu-devel] [PATCH 2/8] spapr: introduce a machine class flag to handle migration compatibility

[Greg Kurz <groug@kaod.org>]

On Sun, 29 Oct 2017 19:12:11 +0100
Cédric Le Goater <clg@kaod.org> wrote:

> Older pseries machines, before 2.11, do not have a bitmap acting as a

We're in hard freeze for 2.11: this should now target 2.12 (David has just
created the ppc-for-2.12 branch).

> IRQ number allocator but use the ICSIRQState array for this purpose.
> This difference between machine versions needs to be taken into
> account when loading the state.
> 
> To keep in sync the bitmap with the ICSIRQState array flags, we
> introduce a machine class flag 'pre_2_11_has_no_bitmap' identifying an
> older version.
> 

Since you're introducing the bitmap in this series, I think you should
rather do the other way around: add a 'has_irq_bitmap' flag to the machine
class defaulting to 'true' in spapr_machine_class_init() and setting it to
'false' for older machine types.

> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  hw/ppc/spapr.c         | 19 +++++++++++++++++++
>  include/hw/ppc/spapr.h |  1 +
>  2 files changed, 20 insertions(+)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 88da4bad2328..b33eebe44906 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1532,6 +1532,7 @@ static bool spapr_vga_init(PCIBus *pci_bus, Error **errp)
>  static int spapr_post_load(void *opaque, int version_id)
>  {
>      sPAPRMachineState *spapr = (sPAPRMachineState *)opaque;
> +    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
>      int err = 0;
>  
>      if (!object_dynamic_cast(OBJECT(spapr->ics), TYPE_ICS_KVM)) {
> @@ -1562,6 +1563,20 @@ static int spapr_post_load(void *opaque, int version_id)
>          }
>      }
>  
> +    /*
> +     * synchronize the IRQ number bitmap with the ICSIRQState array
> +     * coming from an pre-2.11 pseries machine
> +     */
> +    if (smc->pre_2_11_has_no_bitmap) {
> +        int srcno;
> +
> +        for (srcno = 0; srcno < spapr->ics->nr_irqs; srcno++) {
> +            if (spapr->ics->irqs[srcno].flags & XICS_FLAGS_IRQ_MASK &&
> +                !test_bit(srcno, spapr->irq_map)) {
> +                bitmap_set(spapr->irq_map, srcno, 1);
> +            }
> +        }
> +    }
>      return err;
>  }
>  
> @@ -3772,8 +3787,12 @@ static void spapr_machine_2_10_instance_options(MachineState *machine)
>  
>  static void spapr_machine_2_10_class_options(MachineClass *mc)
>  {
> +    sPAPRMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
> +
>      spapr_machine_2_11_class_options(mc);
>      SET_MACHINE_COMPAT(mc, SPAPR_COMPAT_2_10);
> +
> +    smc->pre_2_11_has_no_bitmap = true;
>  }
>  
>  DEFINE_SPAPR_MACHINE(2_10, "2.10", false);
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index b962bfe09bb5..1525d1518c47 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -62,6 +62,7 @@ struct sPAPRMachineClass {
>      bool dr_lmb_enabled;       /* enable dynamic-reconfig/hotplug of LMBs */
>      bool use_ohci_by_default;  /* use USB-OHCI instead of XHCI */
>      bool pre_2_10_has_unused_icps;
> +    bool pre_2_11_has_no_bitmap;
>      void (*phb_placement)(sPAPRMachineState *spapr, uint32_t index,
>                            uint64_t *buid, hwaddr *pio, 
>                            hwaddr *mmio32, hwaddr *mmio64,