From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54352) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fconr-00035S-Bm for qemu-devel@nongnu.org; Tue, 10 Jul 2018 05:19:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fconq-0002xk-6u for qemu-devel@nongnu.org; Tue, 10 Jul 2018 05:19:23 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:49930 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fconq-0002xa-2Q for qemu-devel@nongnu.org; Tue, 10 Jul 2018 05:19:22 -0400 From: Peter Xu Date: Tue, 10 Jul 2018 17:18:55 +0800 Message-Id: <20180710091902.28780-4-peterx@redhat.com> In-Reply-To: <20180710091902.28780-1-peterx@redhat.com> References: <20180710091902.28780-1-peterx@redhat.com> Subject: [Qemu-devel] [PATCH for-3.0 v2 03/10] migration: fix incorrect bitmap size calculation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: peterx@redhat.com, Juan Quintela , "Dr . David Alan Gilbert" , Balamuruhan S The calculation on size of received bitmap is incorrect for postcopy recovery. Here we wanted to let the size to cover all the valid bits in the bitmap, we should use DIV_ROUND_UP() instead of a division. For example, a RAMBlock with size=4K (which contains only one single 4K page) will have nbits=1, then nbits/8=0, then the real bitmap won't be sent to source at all. Reviewed-by: Dr. David Alan Gilbert Reviewed-by: Juan Quintela Signed-off-by: Peter Xu --- migration/ram.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index 49068e86d3..52dd678092 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -235,7 +235,7 @@ int64_t ramblock_recv_bitmap_send(QEMUFile *file, bitmap_to_le(le_bitmap, block->receivedmap, nbits); /* Size of the bitmap, in bytes */ - size = nbits / 8; + size = DIV_ROUND_UP(nbits, 8); /* * size is always aligned to 8 bytes for 64bit machines, but it @@ -3944,7 +3944,7 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block) int ret = -EINVAL; QEMUFile *file = s->rp_state.from_dst_file; unsigned long *le_bitmap, nbits = block->used_length >> TARGET_PAGE_BITS; - uint64_t local_size = nbits / 8; + uint64_t local_size = DIV_ROUND_UP(nbits, 8); uint64_t size, end_mark; trace_ram_dirty_bitmap_reload_begin(block->idstr); -- 2.17.1