target-ppc: Fix CPU migration from qemu-2.6 <-> later versions

When migration for target-ppc was converted to vmstate, several
VMSTATE_EQUAL() checks were foolishly included of things that really
should be internal state.  Specifically we verified equality of the
insns_flags and insns_flags2 fields, which are used within TCG to
determine which groups of instructions are available on this cpu
model.  Between qemu-2.6 and qemu-2.7 we made some changes to these
classes which broke migration.

This path fixes migration both forwards and backwards.  On migration
from 2.6 to later versions we import the fields into teporary
variables, which we then ignore.  In migration backwards, we populate
the temporary fields from the runtime fields, but mask out the bits
which were added after qemu-2.6, allowing the VMSTATE_EQUAL in
qemu-2.6 to accept the stream.

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>

diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index 1c90adb5d7b8fef95d0c5846dc8e3019c5c167cc..7798b2ec2382caffe77f59fe2e1c0b8abc42d38e 100644 (file)
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -1166,6 +1166,12 @@ struct PowerPCCPU {
     int cpu_dt_id;
     uint32_t max_compat;
     uint32_t cpu_version;
+
+    /* fields used only during migration for compatibility hacks */
+    target_ulong mig_msr_mask;
+    uint64_t mig_insns_flags;
+    uint64_t mig_insns_flags2;
+    uint32_t mig_nb_BATs;
 };
 
 static inline PowerPCCPU *ppc_env_get_cpu(CPUPPCState *env)

diff --git a/target-ppc/machine.c b/target-ppc/machine.c
index e43cb6c39d15ad1dea223a3109acb80abe8aaa0a..fcac263c7dea759c3262a6d8557acc10a2bab047 100644 (file)
--- a/target-ppc/machine.c
+++ b/target-ppc/machine.c
@@ -140,6 +140,21 @@ static void cpu_pre_save(void *opaque)
     PowerPCCPU *cpu = opaque;
     CPUPPCState *env = &cpu->env;
     int i;
+    uint64_t insns_compat_mask =
+        PPC_INSNS_BASE | PPC_ISEL | PPC_STRING | PPC_MFTB
+        | PPC_FLOAT | PPC_FLOAT_FSEL | PPC_FLOAT_FRES
+        | PPC_FLOAT_FSQRT | PPC_FLOAT_FRSQRTE | PPC_FLOAT_FRSQRTES
+        | PPC_FLOAT_STFIWX | PPC_FLOAT_EXT
+        | PPC_CACHE | PPC_CACHE_ICBI | PPC_CACHE_DCBZ
+        | PPC_MEM_SYNC | PPC_MEM_EIEIO | PPC_MEM_TLBIE | PPC_MEM_TLBSYNC
+        | PPC_64B | PPC_64BX | PPC_ALTIVEC
+        | PPC_SEGMENT_64B | PPC_SLBI | PPC_POPCNTB | PPC_POPCNTWD;
+    uint64_t insns_compat_mask2 = PPC2_VSX | PPC2_VSX207 | PPC2_DFP | PPC2_DBRX
+        | PPC2_PERM_ISA206 | PPC2_DIVE_ISA206
+        | PPC2_ATOMIC_ISA206 | PPC2_FP_CVT_ISA206
+        | PPC2_FP_TST_ISA206 | PPC2_BCTAR_ISA207
+        | PPC2_LSQ_ISA207 | PPC2_ALTIVEC_207
+        | PPC2_ISA205 | PPC2_ISA207S | PPC2_FP_CVT_S64 | PPC2_TM;
 
     env->spr[SPR_LR] = env->lr;
     env->spr[SPR_CTR] = env->ctr;
@@ -161,6 +176,12 @@ static void cpu_pre_save(void *opaque)
         env->spr[SPR_IBAT4U + 2*i] = env->IBAT[0][i+4];
         env->spr[SPR_IBAT4U + 2*i + 1] = env->IBAT[1][i+4];
     }
+
+    /* 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;
 }
 
 static int cpu_post_load(void *opaque, int version_id)
@@ -561,10 +582,10 @@ const VMStateDescription vmstate_ppc_cpu = {
         /* FIXME: access_type? */
 
         /* Sanity checking */
-        VMSTATE_UINTTL_EQUAL(env.msr_mask, PowerPCCPU),
-        VMSTATE_UINT64_EQUAL(env.insns_flags, PowerPCCPU),
-        VMSTATE_UINT64_EQUAL(env.insns_flags2, PowerPCCPU),
-        VMSTATE_UINT32_EQUAL(env.nb_BATs, PowerPCCPU),
+        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_END_OF_LIST()
     },
     .subsections = (const VMStateDescription*[]) {