Re: [Qemu-devel] scp during migration with vhost fails

[Jason Wang]

On 02/21/2013 07:23 PM, Michael S. Tsirkin wrote:
> On Thu, Feb 21, 2013 at 05:57:04PM +0800, Jason Wang wrote:
>> On 02/21/2013 12:48 AM, Michael S. Tsirkin wrote:
>>> On Wed, Feb 20, 2013 at 04:23:52PM +0200, Michael S. Tsirkin wrote:
>>>> On Fri, Feb 01, 2013 at 06:03:32PM +0800, Jason Wang wrote:
>>>>> Hello all:
>>>>>
>>>>> During testing, I find doing scp during migration with vhost fails with 
>>>>> warnings in guest like:
>>>>>
>>>>> Corrupted MAC on input.
>>>>> Disconnecting: Packet corrupt.
>>>>> lost connection
>>>>>
>>>>> Here's the bisect result:
>>>>>
>>>>> Commit a01672d3968cf91208666d371784110bfde9d4f8 kvm: convert to 
>>>>> MemoryListener 
>>>>> API is the last commit that works well.
>>>>>
>>>>> With commit 04097f7c5957273c578f72b9bd603ba6b1d69e33 vhost: convert to 
>>>>> MemoryListener API, guest network is unusable with warning of "bad gso 
>>>>> type"
>>>>>
>>>>> With commit d743c382861eaa1e13f503b05aba5a382a7e7f7c vhost: fix incorrect 
>>>>> userspace address, guest network is available, but scp during migration 
>>>>> may 
>>>>> fail.
>>>>>
>>>>> Looks like the issue is related to memory api, any thoughts?
>>>>>
>>>>> Thanks
>>>> Tried to reproduce this for a while without success.
>>>> Which command line was used?
>>>>
>>>>
>>>> -- 
>>>> MST
>>> Could be we are not syncing all that we should?
>>> Does the following hack make the problem go away?
>>>
>>> diff --git a/hw/vhost.c b/hw/vhost.c
>>> index 8d41fdb..a7a0412 100644
>>> --- a/hw/vhost.c
>>> +++ b/hw/vhost.c
>>> @@ -69,6 +69,8 @@ static int vhost_sync_dirty_bitmap(struct vhost_dev *dev,
>>>                                     hwaddr end_addr)
>>>  {
>>>      int i;
>>> +    start_addr = 0x0;
>>> +    end_addr = ~0x0ull;
>>>  
>>>      if (!dev->log_enabled || !dev->started) {
>>>          return 0;
>>>
>> Still can reproduce with this. From the bisect result, the vhost dirty
>> bitmap sync itself looks ok but something wrong when converting to
>> memory listener.
> Reading the code carefully, I found two bugs introduced during
> this conversion. Patch below, could you please try?
>
>     vhost: memory sync fixes
>     
>     This fixes two bugs related to memory sync during
>     migration:
>         - ram address calculation was missing the chunk
>           address, so the wrong page was dirtied
>         - one after last was used instead of the
>           end address of a region, which might overflow to 0
>           and cause us to skip the region when the region ends at
>           ~0x0ull.
>     
>     Signed-off-by: Michael S. Tsirkin <address@hidden>
>
> ---
>
> diff --git a/hw/vhost.c b/hw/vhost.c
> index 8d41fdb..dbf6b46 100644
> --- a/hw/vhost.c
> +++ b/hw/vhost.c
> @@ -55,7 +55,7 @@ static void vhost_dev_sync_region(struct vhost_dev *dev,
>                  ffsll(log) : ffs(log))) {
>              ram_addr_t ram_addr;
>              bit -= 1;
> -            ram_addr = section->offset_within_region + bit * VHOST_LOG_PAGE;
> +            ram_addr = section->offset_within_region + addr + bit * 
> VHOST_LOG_PAGE;
>              memory_region_set_dirty(section->mr, ram_addr, VHOST_LOG_PAGE);
>              log &= ~(0x1ull << bit);
>          }
> @@ -94,7 +94,7 @@ static void vhost_log_sync(MemoryListener *listener,
>      struct vhost_dev *dev = container_of(listener, struct vhost_dev,
>                                           memory_listener);
>      hwaddr start_addr = section->offset_within_address_space;
> -    hwaddr end_addr = start_addr + section->size;
> +    hwaddr end_addr = start_addr + section->size - 1;
>  
>      vhost_sync_dirty_bitmap(dev, section, start_addr, end_addr);
>  }
>

I can still reproduce the issue with this patch.