[Xen-changelog] [qemu-xen master] target-ppc: Allow eventual removal of old migration mistakes

[patchbot@xxxxxxx]

commit 146c11f16f12dbfea62cbd7f865614bb6fcbc6b5
Author:     David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
AuthorDate: Mon Nov 21 16:29:30 2016 +1100
Commit:     David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
CommitDate: Wed Nov 23 12:00:48 2016 +1100

    target-ppc: Allow eventual removal of old migration mistakes
    
    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@xxxxxxxxxxxxxxxxxxxxx>
    Reviewed-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx>
    Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx>
    Reviewed-by: Greg Kurz <groug@xxxxxxxx>
    Reviewed-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
---
 hw/ppc/spapr.c              |  5 +++++
 target-ppc/cpu.h            |  3 ++-
 target-ppc/machine.c        | 26 ++++++++++++++++++--------
 target-ppc/translate_init.c |  6 ++++++
 4 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 54b88d3..775ad2e 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -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,
diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index 7798b2e..2a50c43 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -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;
diff --git a/target-ppc/machine.c b/target-ppc/machine.c
index fcac263..18c16d2 100644
--- a/target-ppc/machine.c
+++ b/target-ppc/machine.c
@@ -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;
@@ -178,10 +185,12 @@ static void cpu_pre_save(void *opaque)
     }
 
     /* Hacks for migration compatibility between 2.6, 2.7 & 2.8 */
-    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;
+    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*[]) {
diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
index 208fa1e..626e031 100644
--- a/target-ppc/translate_init.c
+++ b/target-ppc/translate_init.c
@@ -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;
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#master

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