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

[Michael S. Tsirkin]

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;