From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40005) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZETTb-0002JG-1r for qemu-devel@nongnu.org; Sun, 12 Jul 2015 22:28:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZETTX-0002RX-R8 for qemu-devel@nongnu.org; Sun, 12 Jul 2015 22:28:14 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:11796) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZETTX-0002QZ-45 for qemu-devel@nongnu.org; Sun, 12 Jul 2015 22:28:11 -0400 Message-ID: <55A3221C.6090307@huawei.com> Date: Mon, 13 Jul 2015 10:27:40 +0800 From: Linhaifeng MIME-Version: 1.0 References: <1435310564-9418-1-git-send-email-thibaut.collet@6wind.com> <1435310564-9418-2-git-send-email-thibaut.collet@6wind.com> <559FC31E.10600@redhat.com> In-Reply-To: <559FC31E.10600@redhat.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v4 1/1] vhost user: add support of live migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , Thibaut Collet , mst@redhat.com, stefanha@redhat.com, jasowang@redhat.com, qemu-devel@nongnu.org On 2015/7/10 21:05, Paolo Bonzini wrote: > > On 26/06/2015 11:22, Thibaut Collet wrote: >> Some vhost client/backend are able to support live migration. >> To provide this service the following features must be added: >> 1. Add the VIRTIO_NET_F_GUEST_ANNOUNCE capability to vhost-net when netdev >> backend is vhost-user. >> 2. Provide a nop receive callback to vhost-user. This callback is for RARP >> packets automatically send by qemu_announce_self after a migration. >> These packets are useless for vhost user and just discarded. > When a packet is received by vhost-user, the vhost-user writes the > packet in guest memory. QEMU must then copy that page of guest memory > from source to destination; it uses a dirty bitmap for this purpose. > > How does vhost-user do this? I can see this patch providing enough > support for *non*live migration. However, it cannot be enough for live > migration unless I'm missing something obvious. > > Paolo Agree. vhost-user should mmap the log memory and mark dirty pages when send or receive packets. >> Signed-off-by: Thibaut Collet >> --- >> hw/net/vhost_net.c | 2 ++ >> net/vhost-user.c | 21 +++++++++++++++++++-- >> 2 files changed, 21 insertions(+), 2 deletions(-) >> >> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c >> index 9bd360b..668c422 100644 >> --- a/hw/net/vhost_net.c >> +++ b/hw/net/vhost_net.c >> @@ -85,6 +85,8 @@ static const int user_feature_bits[] = { >> VIRTIO_NET_F_CTRL_MAC_ADDR, >> VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, >> >> + VIRTIO_NET_F_GUEST_ANNOUNCE, >> + >> VIRTIO_NET_F_MQ, >> >> VHOST_INVALID_FEATURE_BIT >> diff --git a/net/vhost-user.c b/net/vhost-user.c >> index b51bc04..20778a1 100644 >> --- a/net/vhost-user.c >> +++ b/net/vhost-user.c >> @@ -65,6 +65,24 @@ static void vhost_user_stop(VhostUserState *s) >> s->vhost_net = 0; >> } >> >> +static ssize_t vhost_user_receive(NetClientState *nc, const uint8_t *buf, >> + size_t size) >> +{ >> + /* A live migration is done. Display an error if the packet is not a RARP. >> + * RARP are just discarded: guest is already notified of live migration >> + * by the virtio-net NIC or by the vhost-user backend */ >> + if (size != 60) { >> + static int display_trace = 1; >> + >> + if (display_trace) { >> + fprintf(stderr,"Vhost user receives unexpected packets\n"); >> + fflush(stderr); >> + display_trace = 0; >> + } >> + } >> + return size; >> +} >> + >> static void vhost_user_cleanup(NetClientState *nc) >> { >> VhostUserState *s = DO_UPCAST(VhostUserState, nc, nc); >> @@ -90,6 +108,7 @@ static bool vhost_user_has_ufo(NetClientState *nc) >> static NetClientInfo net_vhost_user_info = { >> .type = NET_CLIENT_OPTIONS_KIND_VHOST_USER, >> .size = sizeof(VhostUserState), >> + .receive = vhost_user_receive, >> .cleanup = vhost_user_cleanup, >> .has_vnet_hdr = vhost_user_has_vnet_hdr, >> .has_ufo = vhost_user_has_ufo, >> @@ -146,8 +165,6 @@ static int net_vhost_user_init(NetClientState *peer, const char *device, >> >> s = DO_UPCAST(VhostUserState, nc, nc); >> >> - /* We don't provide a receive callback */ >> - s->nc.receive_disabled = 1; >> s->chr = chr; >> s->nc.queue_index = i; >> >> > >