Benjamin Herrenschmidt <b...@kernel.crashing.org> writes:

> On Thu, 2016-09-22 at 14:34 +0530, Nikunj A Dadhania wrote:
>> Something like this works for KVM:
>> 
>> diff --git a/target-ppc/machine.c b/target-ppc/machine.c
>> index 4820f22..1cf3779 100644
>> --- a/target-ppc/machine.c
>> +++ b/target-ppc/machine.c
>> @@ -563,8 +563,8 @@ const VMStateDescription vmstate_ppc_cpu = {
>>  
>>          /* Sanity checking */
>>          VMSTATE_UINTTL_EQUAL(env.msr_mask, PowerPCCPU),
>> -        VMSTATE_UINT64_EQUAL(env.insns_flags, PowerPCCPU),
>> -        VMSTATE_UINT64_EQUAL(env.insns_flags2, PowerPCCPU),
>> +        VMSTATE_UNUSED(sizeof(target_ulong)), /* was 
>> _EQUAL(env.insns_flags) */
>> +        VMSTATE_UNUSED(sizeof(target_ulong)), /* was 
>> _EQUAL(env.insns_flags2) */
>>          VMSTATE_UINT32_EQUAL(env.nb_BATs, PowerPCCPU),
>>          VMSTATE_END_OF_LIST()
>>      },
>> 
>> TCG migration still remains broken with this.
>
> Can we have conditionally present flags and a post-load that does some
> matching ?

I think its possible like this:

diff --git a/target-ppc/machine.c b/target-ppc/machine.c
index 4820f22..dc4704e 100644
--- a/target-ppc/machine.c
+++ b/target-ppc/machine.c
@@ -528,6 +528,42 @@ static const VMStateDescription vmstate_tlbmas = {
     }
 };
 
+static bool ppc_kvm_enabled(void *opaque, int version_id)
+{
+    printf("%s: is kvm enabled %d\n", __func__, kvm_enabled());
+    return !kvm_enabled();
+}
+
+static int get_insns_equal(QEMUFile *f, void *pv, size_t size)
+{
+    uint64_t *v = pv;
+    uint64_t v2;
+    qemu_get_be64s(f, &v2);
+
+    printf("%s: \n", __func__);
+
+    if (*v == v2) {
+        return 0;
+    }
+    printf("Did not match, ignore %" PRIu64 " != %" PRIu64 "\n", *v, v2);
+    return 0;
+}
+
+static void put_insns(QEMUFile *f, void *pv, size_t size)
+{
+    uint64_t *v = pv;
+    qemu_put_be64s(f, v);
+}
+
+const VMStateInfo vmstate_info_insns_equal = {
+    .name = "insns equal",
+    .get  = get_insns_equal,
+    .put  = put_insns,
+};
+
+#define VMSTATE_INSNS_EQUAL(_f, _s, _t)                                 \
+    VMSTATE_SINGLE_TEST(_f, _s, _t, 0, vmstate_info_insns_equal, uint64_t)
+
 const VMStateDescription vmstate_ppc_cpu = {
     .name = "cpu",
     .version_id = 5,
@@ -563,8 +599,8 @@ const VMStateDescription vmstate_ppc_cpu = {
 
         /* Sanity checking */
         VMSTATE_UINTTL_EQUAL(env.msr_mask, PowerPCCPU),
-        VMSTATE_UINT64_EQUAL(env.insns_flags, PowerPCCPU),
-        VMSTATE_UINT64_EQUAL(env.insns_flags2, PowerPCCPU),
+        VMSTATE_INSNS_EQUAL(env.insns_flags, PowerPCCPU, ppc_kvm_enabled),
+        VMSTATE_INSNS_EQUAL(env.insns_flags2, PowerPCCPU, ppc_kvm_enabled),
         VMSTATE_UINT32_EQUAL(env.nb_BATs, PowerPCCPU),
         VMSTATE_END_OF_LIST()
     },


TCG migration succeeds and proceeds ahead. But fails somewhere ahead in
powerpc exception handler:

[qemu]$ ./ppc64-softmmu/qemu-system-ppc64  -machine pseries-2.6,usb=off -vga 
none -nographic -m 2G   ../../imgs/guest.disk -monitor pty --incoming 
tcp:localhost:4444 
char device redirected to /dev/pts/5 (label compat_monitor0)
ppc_kvm_enabled: is kvm enabled 0
get_insns_equal: 
Did not match, ignore 9223477658187168481 != 9223477658187151905
ppc_kvm_enabled: is kvm enabled 0
get_insns_equal: 
Did not match, ignore 331702 != 69558
Cannot open font file True
Cannot open font file True
qemu: fatal: Trying to deliver HV exception 4 with no HV support

NIP c0000000000795c8   LR d00000000074407c CTR c000000000079544 XER 
0000000000000000 CPU#0
MSR 8000000000009032 HID0 0000000000000000  HF 8000000000000030 iidx 1 didx 1
TB 00000007 32202510341 DECR 00596259

Regards,
Nikunj


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