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target-ppc: Allow eventual removal of old migration mistakes

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Until very recently, the vmstate for ppc cpus included some poorly
thought out VMSTATE_EQUAL() components, that can easily break
migration compatibility, and did so between qemu-2.6 and later
versions.  A hack was recently added which fixes this migration
breakage, but it leaves the unhelpful cruft of these fields in the
migration stream.

This patch adds a new cpu property allowing these fields to be removed
from the stream entirely.  For the pseries-2.8 machine type - which
comes after the fix - and for all non-pseries machine types - which
aren't mature enough to care about cross-version migration - we remove
the fields from the stream.

For pseries-2.7 and earlier, The migration hack remains in place,
allowing backwards and forwards migration with the older machine
types.

This restricts the migration compatibility cruft to older machine
types, and at least opens the possibility of eventually deprecating
and removing it entirely.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
This commit is contained in:
David Gibson 2016-11-21 16:29:30 +11:00
parent 3fed86eefc
commit 146c11f16f
4 changed files with 31 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
hw/ppc/spapr.c
View File

@ -2767,6 +2767,11 @@ DEFINE_SPAPR_MACHINE(2_8, "2.8", true);
.driver = TYPE_SPAPR_PCI_HOST_BRIDGE, \
.property = "mem64_win_size", \
.value = "0", \
}, \
{ \
.driver = TYPE_POWERPC_CPU, \
.property = "pre-2.8-migration", \
.value = "on", \
},
static void phb_placement_2_7(sPAPRMachineState *spapr, uint32_t index,

3
target-ppc/cpu.h
View File

@ -1167,7 +1167,8 @@ struct PowerPCCPU {
uint32_t max_compat;
uint32_t cpu_version;
/* fields used only during migration for compatibility hacks */
/* Fields related to migration compatibility hacks */
bool pre_2_8_migration;
target_ulong mig_msr_mask;
uint64_t mig_insns_flags;
uint64_t mig_insns_flags2;

18
target-ppc/machine.c
View File

@ -135,6 +135,13 @@ static const VMStateInfo vmstate_info_avr = {
#define VMSTATE_AVR_ARRAY(_f, _s, _n) \
VMSTATE_AVR_ARRAY_V(_f, _s, _n, 0)
static bool cpu_pre_2_8_migration(void *opaque, int version_id)
{
PowerPCCPU *cpu = opaque;
return cpu->pre_2_8_migration;
}
static void cpu_pre_save(void *opaque)
{
PowerPCCPU *cpu = opaque;
@ -178,11 +185,13 @@ static void cpu_pre_save(void *opaque)
}
/* Hacks for migration compatibility between 2.6, 2.7 & 2.8 */
if (cpu->pre_2_8_migration) {
cpu->mig_msr_mask = env->msr_mask;
cpu->mig_insns_flags = env->insns_flags & insns_compat_mask;
cpu->mig_insns_flags2 = env->insns_flags2 & insns_compat_mask2;
cpu->mig_nb_BATs = env->nb_BATs;
}
}
static int cpu_post_load(void *opaque, int version_id)
{
@ -582,10 +591,11 @@ const VMStateDescription vmstate_ppc_cpu = {
/* FIXME: access_type? */
/* Sanity checking */
VMSTATE_UINTTL(mig_msr_mask, PowerPCCPU),
VMSTATE_UINT64(mig_insns_flags, PowerPCCPU),
VMSTATE_UINT64(mig_insns_flags2, PowerPCCPU),
VMSTATE_UINT32(mig_nb_BATs, PowerPCCPU),
VMSTATE_UINTTL_TEST(mig_msr_mask, PowerPCCPU, cpu_pre_2_8_migration),
VMSTATE_UINT64_TEST(mig_insns_flags, PowerPCCPU, cpu_pre_2_8_migration),
VMSTATE_UINT64_TEST(mig_insns_flags2, PowerPCCPU,
cpu_pre_2_8_migration),
VMSTATE_UINT32_TEST(mig_nb_BATs, PowerPCCPU, cpu_pre_2_8_migration),
VMSTATE_END_OF_LIST()
},
.subsections = (const VMStateDescription*[]) {

6
target-ppc/translate_init.c
View File

@ -10520,6 +10520,11 @@ static gchar *ppc_gdb_arch_name(CPUState *cs)
#endif
}
static Property ppc_cpu_properties[] = {
DEFINE_PROP_BOOL("pre-2.8-migration", PowerPCCPU, pre_2_8_migration, false),
DEFINE_PROP_END_OF_LIST(),
};
static void ppc_cpu_class_init(ObjectClass *oc, void *data)
{
PowerPCCPUClass *pcc = POWERPC_CPU_CLASS(oc);
@ -10532,6 +10537,7 @@ static void ppc_cpu_class_init(ObjectClass *oc, void *data)
pcc->interrupts_big_endian = ppc_cpu_interrupts_big_endian_always;
dc->realize = ppc_cpu_realizefn;
dc->unrealize = ppc_cpu_unrealizefn;
dc->props = ppc_cpu_properties;
pcc->parent_reset = cc->reset;
cc->reset = ppc_cpu_reset;