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Re: [Qemu-ppc] [PATCH] spapr/ppc: fix backward migration to QEMU 2.9
From: |
Laurent Vivier |
Subject: |
Re: [Qemu-ppc] [PATCH] spapr/ppc: fix backward migration to QEMU 2.9 |
Date: |
Tue, 20 Jun 2017 15:08:47 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0 |
On 19/06/2017 19:05, Greg Kurz wrote:
> Commit c783b0012708 ("ppc: Rework CPU compatibility testing across
> migration") added a subsection to the vmstate description of CPUs.
> This subsection is sent when the CPU compat_pvr field is non-zero,
> which is likely to happen after CAS negociation (since QEMU 2.9) or
> even before CAS negociation if the user explicitely asked for compat
> mode.
>
> This breaks backward migration of existing pseries-2.9 machine types
> since they don't know about this "compat" subsection:
>
> qemu-system-ppc64: error while loading state for instance 0x0 of
> device 'cpu'
>
> This patch reverts to the behavior of simply ignoring the PVR when
> migrating older machines (ie, let the migration succeed if the user
> is sure that the CPU on the destination is close enough to work).
>
> Signed-off-by: Greg Kurz <address@hidden>
Reviewed-by: Laurent Vivier <address@hidden>
but I think it should be merged with patch ("ppc: Rework CPU
compatibility testing across migration") that is not merged and in the
maintainer tree.
thanks,
Laurent
> ---
> hw/ppc/spapr.c | 7 ++++++-
> target/ppc/cpu.h | 1 +
> target/ppc/machine.c | 2 +-
> target/ppc/translate_init.c | 2 ++
> 4 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index d4d781876b27..265d49bbcd7f 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -3474,7 +3474,12 @@ DEFINE_SPAPR_MACHINE(2_10, "2.10", true);
> * pseries-2.9
> */
> #define SPAPR_COMPAT_2_9 \
> - HW_COMPAT_2_9
> + HW_COMPAT_2_9 \
> + { \
> + .driver = TYPE_POWERPC_CPU, \
> + .property = "pre-2.10-migration", \
> + .value = "on", \
> + }, \
>
> static void spapr_machine_2_9_instance_options(MachineState *machine)
> {
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index 09393e601fd9..6ee2a26a963d 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -1211,6 +1211,7 @@ struct PowerPCCPU {
> uint64_t mig_insns_flags;
> uint64_t mig_insns_flags2;
> uint32_t mig_nb_BATs;
> + bool pre_2_10_migration;
> };
>
> static inline PowerPCCPU *ppc_env_get_cpu(CPUPPCState *env)
> diff --git a/target/ppc/machine.c b/target/ppc/machine.c
> index a29aabe8f079..1b7aede579ea 100644
> --- a/target/ppc/machine.c
> +++ b/target/ppc/machine.c
> @@ -608,7 +608,7 @@ static bool compat_needed(void *opaque)
> PowerPCCPU *cpu = opaque;
>
> assert(!(cpu->compat_pvr && !cpu->vhyp));
> - return (cpu->compat_pvr != 0);
> + return !cpu->pre_2_10_migration && cpu->compat_pvr != 0;
> }
>
> static const VMStateDescription vmstate_compat = {
> diff --git a/target/ppc/translate_init.c b/target/ppc/translate_init.c
> index 53aff5a7b734..783bf98217cc 100644
> --- a/target/ppc/translate_init.c
> +++ b/target/ppc/translate_init.c
> @@ -10610,6 +10610,8 @@ static gchar *ppc_gdb_arch_name(CPUState *cs)
>
> static Property ppc_cpu_properties[] = {
> DEFINE_PROP_BOOL("pre-2.8-migration", PowerPCCPU, pre_2_8_migration,
> false),
> + DEFINE_PROP_BOOL("pre-2.10-migration", PowerPCCPU, pre_2_10_migration,
> + false),
> DEFINE_PROP_END_OF_LIST(),
> };
>
>
>