* Dr. David Alan Gilbert (git) (dgilb...@redhat.com) wrote: > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> > > Hi, > This is a RFC/WIP series that enables postcopy migration > with shared memory to a vhost-user process. > It's based off current-head + Juan's load_cleanup series, and > Alexey's bitmap series (v4). It's very lightly tested and seems > to work, but it's quite rough.
Marc-André asked if I had a git with it all applied; so here we are: https://github.com/dagrh/qemu/commits/vhost g...@github.com:dagrh/qemu.git on the vhost branch Dave > I've modified the vhost-user-bridge (aka vhub) in qemu's tests/ to > use the new feature, since this is about the simplest > client around. > > Structure: > > The basic idea is that near the start of postcopy, the client > opens its own userfaultfd fd and sends that back to QEMU over > the socket it's already using for VHUST_USER_* commands. > Then when VHOST_USER_SET_MEM_TABLE arrives it registers the > areas with userfaultfd and sends the mapped addresses back to QEMU. > > QEMU then reads the clients UFD in it's fault thread and issues > requests back to the source as needed. > QEMU also issues 'WAKE' ioctls on the UFD to let the client know > that the page has arrived and can carry on. > > A new feature (VHOST_USER_PROTOCOL_F_POSTCOPY) is added so that > the QEMU knows the client can talk postcopy. > Three new messages (VHOST_USER_POSTCOPY_{ADVISE/LISTEN/END}) are > added to guide the process along. > > Current known issues: > I've not tested it with hugepages yet; and I suspect the madvises > will need tweaking for it. > > The qemu gets to see the base addresses that the client has its > regions mapped at; that's not great for security > > Take care of deadlocking; any thread in the client that > accesses a userfault protected page can stall. > > There's a nasty hack of a lock around the set_mem_table message. > > I've not looked at the recent IOMMU code. > > Some cleanup and a lot of corner cases need thinking about. > > There are probably plenty of unknown issues as well. > > Test setup: > I'm running on one host at the moment, with the guest > scping a large file from the host as it migrates. > The setup is based on one I found in the vhost-user setups. > You'll need a recent kernel for the shared memory support > in userfaultfd, and userfault isn't that happy if a process > using shared memory core's - so make sure you have the > latest fixes. > > SESS=vhost > ulimit -c unlimited > tmux -L $SESS new-session -d > tmux -L $SESS set-option -g history-limit 30000 > # Start a router using the system qemu > tmux -L $SESS new-window -n router ./x86_64-softmmu/qemu-system-x86_64 -M > none -nographic -net socket,vlan=0,udp=loca > lhost:4444,localaddr=localhost:5555 -net > socket,vlan=0,udp=localhost:4445,localaddr=localhost:5556 -net user,vlan=0 > tmux -L $SESS set-option -g set-remain-on-exit on > # Start source vhost bridge > tmux -L $SESS new-window -n srcvhostbr "./tests/vhost-user-bridge -u > /tmp/vubrsrc.sock 2>src-vub-log" > sleep 0.5 > tmux -L $SESS new-window -n source "./x86_64-softmmu/qemu-system-x86_64 > -enable-kvm -m 8G -smp 2 -object memory-backe > nd-file,id=mem,size=8G,mem-path=/dev/shm,share=on -numa node,memdev=mem > -mem-prealloc -chardev socket,id=char0,path=/ > tmp/vubrsrc.sock -netdev type=vhost-user,id=mynet1,chardev=char0,vhostforce > -device virtio-net-pci,netdev=mynet1 my.qcow2 -net none -vnc :0 -monitor > stdio -trace events=/root/trace-file 2>src-qemu-log " > # Start dest vhost bridge > tmux -L $SESS new-window -n destvhostbr "./tests/vhost-user-bridge -u > /tmp/vubrdst.sock -l 127.0.0.1:4445 -r 127.0.0. > 1:5556 2>dst-vub-log" > sleep 0.5 > tmux -L $SESS new-window -n dest "./x86_64-softmmu/qemu-system-x86_64 > -enable-kvm -m 8G -smp 2 -object memory-backend > -file,id=mem,size=8G,mem-path=/dev/shm,share=on -numa node,memdev=mem > -mem-prealloc -chardev socket,id=char0,path=/tm > p/vubrdst.sock -netdev type=vhost-user,id=mynet1,chardev=char0,vhostforce > -device virtio-net-pci,netdev=mynet1 my.qcow2 -net none -vnc :1 -monitor > stdio -incoming tcp::8888 -trace events=/root/trace-file 2>dst-qemu-log" > tmux -L $SESS send-keys -t source "migrate_set_capability postcopy-ram on > tmux -L $SESS send-keys -t source "migrate_set_speed 20M > tmux -L $SESS send-keys -t dest "migrate_set_capability postcopy-ram on > > then once booted: > tmux -L vhost send-keys -t source 'migrate -d tcp:0:8888^M' > tmux -L vhost send-keys -t source 'migrate_start_postcopy^M' > (Note those ^M's are actual ctrl-M's i.e. ctrl-v ctrl-M) > > > Dave > > Dr. David Alan Gilbert (29): > RAMBlock/migration: Add migration flags > migrate: Update ram_block_discard_range for shared > qemu_ram_block_host_offset > migration/ram: ramblock_recv_bitmap_test_byte_offset > postcopy: use UFFDIO_ZEROPAGE only when available > postcopy: Add notifier chain > postcopy: Add vhost-user flag for postcopy and check it > vhost-user: Add 'VHOST_USER_POSTCOPY_ADVISE' message > vhub: Support sending fds back to qemu > vhub: Open userfaultfd > postcopy: Allow registering of fd handler > vhost+postcopy: Register shared ufd with postcopy > vhost+postcopy: Transmit 'listen' to client > vhost+postcopy: Register new regions with the ufd > vhost+postcopy: Send address back to qemu > vhost+postcopy: Stash RAMBlock and offset > vhost+postcopy: Send requests to source for shared pages > vhost+postcopy: Resolve client address > postcopy: wake shared > postcopy: postcopy_notify_shared_wake > vhost+postcopy: Add vhost waker > vhost+postcopy: Call wakeups > vub+postcopy: madvises > vhost+postcopy: Lock around set_mem_table > vhu: enable = false on get_vring_base > vhost: Add VHOST_USER_POSTCOPY_END message > vhost+postcopy: Wire up POSTCOPY_END notify > postcopy: Allow shared memory > vhost-user: Claim support for postcopy > > contrib/libvhost-user/libvhost-user.c | 178 ++++++++++++++++- > contrib/libvhost-user/libvhost-user.h | 8 + > exec.c | 44 +++-- > hw/virtio/trace-events | 13 ++ > hw/virtio/vhost-user.c | 293 +++++++++++++++++++++++++++- > include/exec/cpu-common.h | 3 + > include/exec/ram_addr.h | 2 + > migration/migration.c | 3 + > migration/migration.h | 8 + > migration/postcopy-ram.c | 357 > +++++++++++++++++++++++++++------- > migration/postcopy-ram.h | 69 +++++++ > migration/ram.c | 5 + > migration/ram.h | 1 + > migration/savevm.c | 13 ++ > migration/trace-events | 6 + > trace-events | 3 + > vl.c | 4 +- > 17 files changed, 926 insertions(+), 84 deletions(-) > > -- > 2.13.0 > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK