Re: [Qemu-ppc] pseries-2.6 migration from QEMU-2.6 to QEMU-2.7 broken

[Cédric Le Goater]

On 09/22/2016 01:07 PM, Nikunj A Dadhania wrote:
> Benjamin Herrenschmidt <address@hidden> 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

hmm, this is because we added MSR_HVB in msr_mask AFAICT. we should have 
a similar vmstate op for it I think

C. 

> 
> 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
>