From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51604) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XMnkW-0007zf-NR for qemu-devel@nongnu.org; Wed, 27 Aug 2014 20:39:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XMnkS-0005D1-9b for qemu-devel@nongnu.org; Wed, 27 Aug 2014 20:39:36 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:62983) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XMnkR-0005Cr-Ly for qemu-devel@nongnu.org; Wed, 27 Aug 2014 20:39:32 -0400 Message-ID: <53FE7A21.9090503@huawei.com> Date: Thu, 28 Aug 2014 08:38:57 +0800 From: zhanghailiang MIME-Version: 1.0 References: <1409040377-12088-1-git-send-email-zhang.zhanghailiang@huawei.com> <20140827115321.GB16850@redhat.com> <20140827115949.GA17119@redhat.com> In-Reply-To: <20140827115949.GA17119@redhat.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH V4] net: Forbid dealing with packets when VM is not running List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: aliguori@amazon.com, jasowang@redhat.com, luonengjun@huawei.com, peter.huangpeng@huawei.com, qemu-devel@nongnu.org, stefanha@redhat.com On 2014/8/27 19:59, Michael S. Tsirkin wrote: > On Wed, Aug 27, 2014 at 01:53:21PM +0200, Michael S. Tsirkin wrote: >> On Tue, Aug 26, 2014 at 04:06:17PM +0800, zhanghailiang wrote: >>> For all NICs(except virtio-net) emulated by qemu, >>> Such as e1000, rtl8139, pcnet and ne2k_pci, >>> Qemu can still receive packets when VM is not running. >>> >>> If this happened in *migration's* last PAUSE VM stage, but >>> before the end of the migration, the new receiving packets will possibly dirty >>> parts of RAM which has been cached in *iovec*(will be sent asynchronously) and >>> dirty parts of new RAM which will be missed. >>> This will lead serious network fault in VM. >>> >>> To avoid this, we forbid receiving packets in generic net code when >>> VM is not running. >>> >>> Bug reproduction steps: >>> (1) Start a VM which configured at least one NIC >>> (2) In VM, open several Terminal and do *Ping IP -i 0.1* >>> (3) Migrate the VM repeatedly between two Hosts >>> And the *PING* command in VM will very likely fail with message: >>> 'Destination HOST Unreachable', the NIC in VM will stay unavailable unless you >>> run 'service network restart' >>> >>> Signed-off-by: zhanghailiang >> >> Reviewed-by: Michael S. Tsirkin > > Please add: > Cc: qemu-stable@nongnu.org > > when applying this. > > Thanks! > OK! Thanks. > >>> --- >>> v4: >>> - The action of flush queued packets is unnecessary, remove this. >>> (Thanks for the help of Jason Wang and Stefan). >>> >>> v3: >>> - change the 'vmstate' to 'vm_running' >>> >>> v2: >>> - remove the superfluous check of nc->received_disabled >>> --- >>> >>> net/net.c | 7 +++++++ >>> 1 file changed, 7 insertions(+) >>> >>> diff --git a/net/net.c b/net/net.c >>> index 6d930ea..4cb92c0 100644 >>> --- a/net/net.c >>> +++ b/net/net.c >>> @@ -41,6 +41,7 @@ >>> #include "qapi-visit.h" >>> #include "qapi/opts-visitor.h" >>> #include "qapi/dealloc-visitor.h" >>> +#include "sysemu/sysemu.h" >>> >>> /* Net bridge is currently not supported for W32. */ >>> #if !defined(_WIN32) >>> @@ -452,6 +453,12 @@ void qemu_set_vnet_hdr_len(NetClientState *nc, int len) >>> >>> int qemu_can_send_packet(NetClientState *sender) >>> { >>> + int vm_running = runstate_is_running(); >>> + >>> + if (!vm_running) { >>> + return 0; >>> + } >>> + >>> if (!sender->peer) { >>> return 1; >>> } >>> -- >>> 1.7.12.4 >>> > > . >