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

[Jason Wang]

On 02/24/2013 05:54 AM, Michael S. Tsirkin wrote:
> On Sat, Feb 23, 2013 at 10:49:29PM +0200, Michael S. Tsirkin wrote:
>> On Fri, Feb 22, 2013 at 11:33:53PM +0800, Jason Wang wrote:
>>> 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.
>>
>> Yes it's still wrong. We need the following on top.
>> Could you try please?
>>
>> diff --git a/hw/vhost.c b/hw/vhost.c
>> index dbf6b46..c324903 100644
>> --- a/hw/vhost.c
>> +++ b/hw/vhost.c
>> @@ -29,7 +29,7 @@ static void vhost_dev_sync_region(struct vhost_dev *dev,
>>      uint64_t end = MIN(mlast, rlast);
>>      vhost_log_chunk_t *from = dev->log + start / VHOST_LOG_CHUNK;
>>      vhost_log_chunk_t *to = dev->log + end / VHOST_LOG_CHUNK + 1;
>> -    uint64_t addr = (start / VHOST_LOG_CHUNK) * VHOST_LOG_CHUNK;
>> +    uint64_t addr = 0;
>>  
>>      if (end < start) {
>>          return;
>
> Sorry, scratch that last one, sorry.
> This should be the right thing, I think: on top of
> 'vhost: memory sync fixes'.
>
> diff --git a/hw/vhost.c b/hw/vhost.c
> index dbf6b46..72c0095 100644
> --- a/hw/vhost.c
> +++ b/hw/vhost.c
> @@ -53,9 +53,10 @@ static void vhost_dev_sync_region(struct vhost_dev *dev,
>          log = __sync_fetch_and_and(from, 0);
>          while ((bit = sizeof(log) > sizeof(int) ?
>                  ffsll(log) : ffs(log))) {
> -            ram_addr_t ram_addr;
> +            hwaddr ram_addr;
>              bit -= 1;
> -            ram_addr = section->offset_within_region + addr + bit * 
> VHOST_LOG_PAGE;
> +            ram_addr = addr + bit * VHOST_LOG_PAGE -
> +                section->mr->offset_within_address_space;

should be section->offset_within_address_space
>              memory_region_set_dirty(section->mr, ram_addr, VHOST_LOG_PAGE);
>              log &= ~(0x1ull << bit);
>          }
>
>

Still can reproduce. An interesting thing is after I chage the
section->offset_within_address_space to section->mr->ram_addr[1]. I
can't reproduce the issue. I haven't read all the codes, but it looks
like something is wrong with the valueof
section->offset_within_address_space? Thanks

[1]
diff --git a/hw/vhost.c b/hw/vhost.c
index 8d41fdb..785e68e 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 = addr + bit * VHOST_LOG_PAGE - section->mr->ram_addr;
             memory_region_set_dirty(section->mr, ram_addr, VHOST_LOG_PAGE);
             log &= ~(0x1ull << bit);
         }