On 01/03/2018 12:33 PM, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> > > This code has an optimised, word aligned version, and a boring > unaligned version. My commit f70d345 fixed one alignment issue, but > there's another. > > The optimised version operates on 'longs' dealing with (typically) 64 > pages at a time, replacing the whole long by a 0 and counting the bits. > If the Ramblock is less than 64bits in length that long can contain bits > representing two different RAMBlocks, but the code will update the > bmap belinging to the 1st RAMBlock only while having updated the total > dirty page count for both. > > This probably didn't matter prior to 6b6712ef which split the dirty > bitmap by RAMBlock, but now they're separate RAMBlocks we end up > with a count that doesn't match the state in the bitmaps. > > Symptom: > Migration showing a few dirty pages left to be sent constantly > Seen on aarch64 and x86 with x86+ovmf > > Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com> > Reported-by: Wei Huang <w...@redhat.com> > Fixes: 6b6712efccd383b48a909bee0b29e079a57601ec
This solves the failure I saw in the migration test case. Acked-by: Wei Huang <w...@redhat.com> > --- > include/exec/ram_addr.h | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h > index 6cbc02aa0f..7633ef6342 100644 > --- a/include/exec/ram_addr.h > +++ b/include/exec/ram_addr.h > @@ -391,9 +391,10 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock > *rb, > uint64_t num_dirty = 0; > unsigned long *dest = rb->bmap; > > - /* start address is aligned at the start of a word? */ > + /* start address and length is aligned at the start of a word? */ > if (((word * BITS_PER_LONG) << TARGET_PAGE_BITS) == > - (start + rb->offset)) { > + (start + rb->offset) && > + !(length & ((BITS_PER_LONG << TARGET_PAGE_BITS) - 1))) { > int k; > int nr = BITS_TO_LONGS(length >> TARGET_PAGE_BITS); > unsigned long * const *src; >