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Re: [Qemu-devel] [PULL RESEND 12/19] vmxnet3: Convert ring values to uin


From: Laurent Vivier
Subject: Re: [Qemu-devel] [PULL RESEND 12/19] vmxnet3: Convert ring values to uint32_t's
Date: Tue, 14 Mar 2017 14:42:28 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0

On 14/03/2017 14:31, Dr. David Alan Gilbert wrote:
> * Laurent Vivier (address@hidden) wrote:
>> On 14/03/2017 12:38, Dr. David Alan Gilbert wrote:
>>> * Laurent Vivier (address@hidden) wrote:
>>>> On 14/03/2017 12:16, Dr. David Alan Gilbert wrote:
>>>>> * Laurent Vivier (address@hidden) wrote:
>>>>>> On 06/03/2017 06:25, Jason Wang wrote:
>>>>>>> From: "Dr. David Alan Gilbert" <address@hidden>
>>>>>>>
>>>>>>> The index's in the Vmxnet3Ring were migrated as 32bit ints
>>>>>>> yet are declared as size_t's.  They appear to be derived
>>>>>>> from 32bit values loaded from guest memory, so actually
>>>>>>> store them as that.
>>>>>>>
>>>>>>> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
>>>>>>> Acked-by: Dmitry Fleytman <address@hidden>
>>>>>>> Signed-off-by: Jason Wang <address@hidden>
>>>>>>> ---
>>>>>>>  hw/net/vmxnet3.c | 12 ++++++------
>>>>>>>  1 file changed, 6 insertions(+), 6 deletions(-)
>>>>>>>
>>>>>>> diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
>>>>>>> index e13a798..224c109 100644
>>>>>>> --- a/hw/net/vmxnet3.c
>>>>>>> +++ b/hw/net/vmxnet3.c
>>>>>>> @@ -141,17 +141,17 @@ typedef struct VMXNET3Class {
>>>>>>>  /* Cyclic ring abstraction */
>>>>>>>  typedef struct {
>>>>>>>      hwaddr pa;
>>>>>>> -    size_t size;
>>>>>>> -    size_t cell_size;
>>>>>>> -    size_t next;
>>>>>>> +    uint32_t size;
>>>>>>> +    uint32_t cell_size;
>>>>>>> +    uint32_t next;
>>>>>>>      uint8_t gen;
>>>>>>>  } Vmxnet3Ring;
>>>>>>>  
>>>>>>>  static inline void vmxnet3_ring_init(PCIDevice *d,
>>>>>>>                                      Vmxnet3Ring *ring,
>>>>>>>                                       hwaddr pa,
>>>>>>> -                                     size_t size,
>>>>>>> -                                     size_t cell_size,
>>>>>>> +                                     uint32_t size,
>>>>>>> +                                     uint32_t cell_size,
>>>>>>>                                       bool zero_region)
>>>>>>>  {
>>>>>>>      ring->pa = pa;
>>>>>>> @@ -166,7 +166,7 @@ static inline void vmxnet3_ring_init(PCIDevice *d,
>>>>>>>  }
>>>>>>>  
>>>>>>>  #define VMXNET3_RING_DUMP(macro, ring_name, ridx, r)                   
>>>>>>>       \
>>>>>>> -    macro("%s#%d: base %" PRIx64 " size %zu cell_size %zu gen %d next 
>>>>>>> %zu",  \
>>>>>>> +    macro("%s#%d: base %" PRIx64 " size %u cell_size %u gen %d next 
>>>>>>> %u",  \
>>>>>>>            (ring_name), (ridx),                                         
>>>>>>>       \
>>>>>>>            (r)->pa, (r)->size, (r)->cell_size, (r)->gen, (r)->next)
>>>>>>>  
>>>>>>>
>>>>>>
>>>>>>
>>>>>> David, with '-dump-vmstate' with 2.8 machine type and with v2.8 and
>>>>>> master I can see the size of "txq_descr" and "rxq_descr" changes because
>>>>>> of "sizeof(Vmxnet3TxqDescr)" and "sizeof(Vmxnet3RxqDescr)". This changes
>>>>>> because the size of Vmxnet3Ring has changed with the s/size_t/uint32_t/":
>>>>>>
>>>>>>         {
>>>>>>           "field": "txq_descr",
>>>>>>           "version_id": 0,
>>>>>>           "field_exists": false,
>>>>>>           "size": 176
>>>>>>         },
>>>>>>         {
>>>>>>           "field": "rxq_descr",
>>>>>>           "version_id": 0,
>>>>>>           "field_exists": false,
>>>>>>           "size": 216
>>>>>>         },
>>>>>>
>>>>>> becomes:
>>>>>>
>>>>>>         {
>>>>>>           "field": "txq_descr",
>>>>>>           "version_id": 0,
>>>>>>           "field_exists": false,
>>>>>>           "size": 144
>>>>>>         },
>>>>>>         {
>>>>>>           "field": "rxq_descr",
>>>>>>           "version_id": 0,
>>>>>>           "field_exists": false,
>>>>>>           "size": 168
>>>>>>         },
>>>>>
>>>>> But the old migration code used to write these fields using qemu_put_be32
>>>>> (from a11f5cb005f9854f0d78da97fc23adf5bc8c83f3)
>>>>>
>>>>> -static void vmxnet3_put_ring_to_file(QEMUFile *f, Vmxnet3Ring *r)
>>>>> -{
>>>>> -    qemu_put_be64(f, r->pa);
>>>>> -    qemu_put_be32(f, r->size);
>>>>> -    qemu_put_be32(f, r->cell_size);
>>>>> -    qemu_put_be32(f, r->next);
>>>>> -    qemu_put_byte(f, r->gen);
>>>>> -}
>>>>>
>>>>> +static const VMStateDescription vmstate_vmxnet3_ring = {
>>>>> +    .name = "vmxnet3-ring",
>>>>> +    .version_id = 0,
>>>>> +    .fields = (VMStateField[]) {
>>>>> +        VMSTATE_UINT64(pa, Vmxnet3Ring),
>>>>> +        VMSTATE_UINT32(size, Vmxnet3Ring),
>>>>> +        VMSTATE_UINT32(cell_size, Vmxnet3Ring),
>>>>> +        VMSTATE_UINT32(next, Vmxnet3Ring),
>>>>> +        VMSTATE_UINT8(gen, Vmxnet3Ring),
>>>>> +        VMSTATE_END_OF_LIST()
>>>>> +    }
>>>>>  };
>>>>>
>>>>> so they used to be size_t's written with be32 and now they're uint32_t's
>>>>> written as 32bit - so that should be the same.
>>>>> I'm not sure i understand where the old txq_descr sizes come from - what
>>>>> managed to print the 176 number before it was converted to VMState?
>>>>
>>>> I think it comes from the sizeof() in VMSTATE_STRUCT(Vmxnet3TxqDescr):
>>>>
>>>> static const VMStateDescription vmstate_vmxnet3_txq_descr = {
>>>>     .name = "vmxnet3-txq-descr",
>>>>     .version_id = 0,
>>>>     .fields = (VMStateField[]) {
>>>>         VMSTATE_STRUCT(tx_ring, Vmxnet3TxqDescr, 0, vmstate_vmxnet3_ring,
>>>>                        Vmxnet3Ring),
>>>>         VMSTATE_STRUCT(comp_ring, Vmxnet3TxqDescr, 0, vmstate_vmxnet3_ring,
>>>>                        Vmxnet3Ring),
>>>>         VMSTATE_UINT8(intr_idx, Vmxnet3TxqDescr),
>>>>         VMSTATE_UINT64(tx_stats_pa, Vmxnet3TxqDescr),
>>>>         VMSTATE_STRUCT(txq_stats, Vmxnet3TxqDescr, 0,
>>>> vmstate_vmxnet3_tx_stats,
>>>>                        struct UPT1_TxStats),
>>>>         VMSTATE_END_OF_LIST()
>>>>     }
>>>> };
>>>>
>>>> I will check the '-dump-vmstate' code to see if it's relevant.
>>>
>>> OK, but that sizeof() should never make it onto the wire; all that
>>> teh VMSTATE_STRUCT should do is execute the vmstate_vmxnet3_ring on
>>> that data.
>>> (And again I'm curious what happened in the version before I committed
>>> that change).
>>>
>>>>>
>>>>>> And if I try a migration, I have:
>>>>>>
>>>>>> qemu/migration/vmstate.c:112: vmstate_load_state: Assertion `first_elem
>>>>>> || !n_elems' failed.
>>>>>
>>>>> Interesting; that's Halil's new assert; I need to look.
>>>>
>>>> Can't it be related to the size problem?
>>>
>>> It could, I need to see exactly how it's failing; what was the full
>>> command line you used, and with what guest?
>>
>> Tested with pseries machine type on ppc64le host, no guest started.
>>
>> qemu-system-ppc64 -M pseries-2.8 -S -serial mon:stdio -vnc :0 -device
>> vmxnet3
> 
> QingFeng Hao's <address@hidden> patch:
>   'vmstate: fix failed iotests case 68 and 91'
> seems to fix that for me.

For me too.

Thanks,
Laurent




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