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

[Michael S. Tsirkin]

On Mon, Feb 25, 2013 at 02:11:44PM +0800, Jason Wang wrote:
> On 02/25/2013 01:57 PM, Jason Wang wrote:
> > 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
> 
> It's ok since we need offset inside the region as the second parameter
> of memory_region_set_dirty().
> >
> > [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);
> >          }
> >
> >


OK I think now I get it.
The following should be the real thing.


diff --git a/hw/vhost.c b/hw/vhost.c
index dbf6b46..2d8ead8 100644
--- a/hw/vhost.c
+++ b/hw/vhost.c
@@ -53,10 +53,14 @@ 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 page_addr;
+            hwaddr section_offset;
+            hwaddr mr_offset;
             bit -= 1;
-            ram_addr = section->offset_within_region + addr + bit * 
VHOST_LOG_PAGE;
-            memory_region_set_dirty(section->mr, ram_addr, VHOST_LOG_PAGE);
+            page_addr = addr + bit * VHOST_LOG_PAGE;
+            section_offset = ram_addr - section->offset_within_address_space;
+            mr_offset = section_offset + section->offset_within_region;
+            memory_region_set_dirty(section->mr, mr_offset, VHOST_LOG_PAGE);
             log &= ~(0x1ull << bit);
         }
         addr += VHOST_LOG_CHUNK;