On Wed, May 22, 2019 at 03:43:46PM +0200, Greg Kurz wrote: > Commit 0b8c89be7f7b added the hpt_maxpagesize capability to the migration > stream. This is okay for new machine types but it breaks backward migration > to older QEMUs, which don't expect the extra subsection. > > Add a compatibility boolean flag to the sPAPR machine class and use it to > skip migration of the capability for machine types 4.0 and older. This > fixes migration to an older QEMU. Note that the destination will emit a > warning: > > qemu-system-ppc64: warning: cap-hpt-max-page-size lower level (16) in > incoming stream than on destination (24) > > This is expected and harmless though. It is okay to migrate from a lower > HPT maximum page size (64k) to a greater one (16M). > > Fixes: 0b8c89be7f7b "spapr: Add forgotten capability to migration stream" > Based-on: <20190522074016.10521-3-...@kaod.org> > Signed-off-by: Greg Kurz <gr...@kaod.org>
Applied, thanks.
> ---
>
> Please notice that this is based on Cedric's patch that make "dual" the
> default for the ic-mode property.
> ---
> hw/ppc/spapr.c | 1 +
> hw/ppc/spapr_caps.c | 12 +++++++++++-
> include/hw/ppc/spapr.h | 1 +
> 3 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 4fd16b43f014..e2b33e5890ae 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -4431,6 +4431,7 @@ static void
> spapr_machine_4_0_class_options(MachineClass *mc)
> compat_props_add(mc->compat_props, hw_compat_4_0, hw_compat_4_0_len);
> smc->phb_placement = phb_placement_4_0;
> smc->irq = &spapr_irq_xics;
> + smc->pre_4_1_migration = true;
> }
>
> DEFINE_SPAPR_MACHINE(4_0, "4.0", false);
> diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c
> index 658eb15a147b..31b466139975 100644
> --- a/hw/ppc/spapr_caps.c
> +++ b/hw/ppc/spapr_caps.c
> @@ -64,6 +64,7 @@ typedef struct SpaprCapabilityInfo {
> void (*apply)(SpaprMachineState *spapr, uint8_t val, Error **errp);
> void (*cpu_apply)(SpaprMachineState *spapr, PowerPCCPU *cpu,
> uint8_t val, Error **errp);
> + bool (*migrate_needed)(void *opaque);
> } SpaprCapabilityInfo;
>
> static void spapr_cap_get_bool(Object *obj, Visitor *v, const char *name,
> @@ -350,6 +351,11 @@ static void cap_hpt_maxpagesize_apply(SpaprMachineState
> *spapr,
> spapr_check_pagesize(spapr, qemu_minrampagesize(), errp);
> }
>
> +static bool cap_hpt_maxpagesize_migrate_needed(void *opaque)
> +{
> + return !SPAPR_MACHINE_GET_CLASS(opaque)->pre_4_1_migration;
> +}
> +
> static bool spapr_pagesize_cb(void *opaque, uint32_t seg_pshift,
> uint32_t pshift)
> {
> @@ -542,6 +548,7 @@ SpaprCapabilityInfo capability_table[SPAPR_CAP_NUM] = {
> .type = "int",
> .apply = cap_hpt_maxpagesize_apply,
> .cpu_apply = cap_hpt_maxpagesize_cpu_apply,
> + .migrate_needed = cap_hpt_maxpagesize_migrate_needed,
> },
> [SPAPR_CAP_NESTED_KVM_HV] = {
> .name = "nested-hv",
> @@ -679,8 +686,11 @@ int spapr_caps_post_migration(SpaprMachineState *spapr)
> static bool spapr_cap_##sname##_needed(void *opaque) \
> { \
> SpaprMachineState *spapr = opaque; \
> + bool (*needed)(void *opaque) = \
> + capability_table[cap].migrate_needed; \
> \
> - return spapr->cmd_line_caps[cap] && \
> + return needed ? needed(opaque) : true && \
> + spapr->cmd_line_caps[cap] && \
> (spapr->eff.caps[cap] != \
> spapr->def.caps[cap]); \
> } \
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 9fc91c8f5eac..4f5becf1f3cc 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -119,6 +119,7 @@ struct SpaprMachineClass {
> bool pre_2_10_has_unused_icps;
> bool legacy_irq_allocation;
> bool broken_host_serial_model; /* present real host info to the guest */
> + bool pre_4_1_migration; /* don't migrate hpt-max-page-size */
>
> void (*phb_placement)(SpaprMachineState *spapr, uint32_t index,
> uint64_t *buid, hwaddr *pio,
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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