On Thu, Dec 06, 2018 at 09:57:22PM +0800, Jason Wang wrote: > > On 2018/12/6 下午2:35, elohi...@gmail.com wrote: > > From: Xie Yongji <xieyon...@baidu.com> > > > > This patchset is aimed at supporting qemu to reconnect > > vhost-user-blk backend after vhost-user-blk backend crash or > > restart. > > > > The patch 1 tries to implenment the sync connection for > > "reconnect socket". > > > > The patch 2 introduces a new message VHOST_USER_SET_VRING_INFLIGHT > > to support offering shared memory to backend to record > > its inflight I/O. > > > > The patch 3,4 are the corresponding libvhost-user patches of > > patch 2. Make libvhost-user support VHOST_USER_SET_VRING_INFLIGHT. > > > > The patch 5 supports vhost-user-blk to reconnect backend when > > connection closed. > > > > The patch 6 tells qemu that we support reconnecting now. > > > > To use it, we could start qemu with: > > > > qemu-system-x86_64 \ > > -chardev socket,id=char0,path=/path/vhost.socket,reconnect=1,wait \ > > -device vhost-user-blk-pci,chardev=char0 \ > > > > and start vhost-user-blk backend with: > > > > vhost-user-blk -b /path/file -s /path/vhost.socket > > > > Then we can restart vhost-user-blk at any time during VM running. > > > I wonder whether or not it's better to handle this at the level of virtio > protocol itself instead of vhost-user level. E.g expose last_avail_idx to > driver might be sufficient? > > Another possible issue is, looks like you need to deal with different kinds > of ring layouts e.g packed virtqueues. > > Thanks
I'm not sure I understand your comments here. All these would be guest-visible extensions. Possible for sure but how is this related to a patch supporting transparent reconnects? > > > > > Xie Yongji (6): > > char-socket: Enable "wait" option for client mode > > vhost-user: Add shared memory to record inflight I/O > > libvhost-user: Introduce vu_queue_map_desc() > > libvhost-user: Support recording inflight I/O in shared memory > > vhost-user-blk: Add support for reconnecting backend > > contrib/vhost-user-blk: enable inflight I/O recording > > > > chardev/char-socket.c | 5 +- > > contrib/libvhost-user/libvhost-user.c | 215 ++++++++++++++++++++---- > > contrib/libvhost-user/libvhost-user.h | 19 +++ > > contrib/vhost-user-blk/vhost-user-blk.c | 3 +- > > hw/block/vhost-user-blk.c | 169 +++++++++++++++++-- > > hw/virtio/vhost-user.c | 69 ++++++++ > > hw/virtio/vhost.c | 8 + > > include/hw/virtio/vhost-backend.h | 4 + > > include/hw/virtio/vhost-user-blk.h | 4 + > > include/hw/virtio/vhost-user.h | 8 + > > 10 files changed, 452 insertions(+), 52 deletions(-) > >
