From e1d64c084b2cc7e907b4e64026d8c8dba59116f8 Mon Sep 17 00:00:00 2001 From: zhanghailiang Date: Tue, 26 Aug 2014 16:06:17 +0800 Subject: [PATCH] net: Forbid dealing with packets when VM is not running 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: Jason Wang Reviewed-by: Juan Quintela Reviewed-by: Michael S. Tsirkin Signed-off-by: Stefan Hajnoczi --- net/net.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/net.c b/net/net.c index 6d930ea63b..962c05f6db 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; } -- 2.11.4.GIT