Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/4] ppc: add CPU IRQ state to PPC VMStateDescription

[Greg Kurz <groug@kaod.org>]

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On Sun, 10 Sep 2017 15:37:33 +0100
Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> wrote:

> Commit a90db15 "target-ppc: Convert ppc cpu savevm to VMStateDescription"
> appears to drop the internal CPU IRQ state from the migration stream. Whilst
> testing migration on g3beige/mac99 machines, test images would randomly fail to
> resume unless a key was pressed on the VGA console.
> 
> Further investigation suggests that internal CPU IRQ state isn't being
> preserved and so interrupts asserted at the time of migration are lost. Adding
> the pending_interrupts and irq_input_state fields back into the migration
> stream appears to fix the problem here during local tests.
> 
> As part of this commit we bump the vmstate_ppc version from 5 to 6 to handle
> the additional fields.
> 

And so this unconditionally breaks backward migration... what about adding
a subsection for this ?

> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
> ---
>  target/ppc/machine.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/target/ppc/machine.c b/target/ppc/machine.c
> index e59049f..8fec1a4 100644
> --- a/target/ppc/machine.c
> +++ b/target/ppc/machine.c
> @@ -647,7 +647,7 @@ static const VMStateDescription vmstate_compat = {
>  
>  const VMStateDescription vmstate_ppc_cpu = {
>      .name = "cpu",
> -    .version_id = 5,
> +    .version_id = 6,
>      .minimum_version_id = 5,
>      .minimum_version_id_old = 4,
>      .load_state_old = cpu_load_old,
> @@ -678,6 +678,10 @@ const VMStateDescription vmstate_ppc_cpu = {
>          VMSTATE_UINTTL(env.hflags_nmsr, PowerPCCPU),
>          /* FIXME: access_type? */
>  
> +        /* Interrupt state */
> +        VMSTATE_UINT32_V(env.pending_interrupts, PowerPCCPU, 6),
> +        VMSTATE_UINT32_V(env.irq_input_state, PowerPCCPU, 6),
> +
>          /* Sanity checking */
>          VMSTATE_UINTTL_TEST(mig_msr_mask, PowerPCCPU, cpu_pre_2_8_migration),
>          VMSTATE_UINT64_TEST(mig_insns_flags, PowerPCCPU, cpu_pre_2_8_migration),


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