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

[Michael S. Tsirkin]

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);
 }