Hyper-V Sockets (hv_sock) supplies a byte-stream based communication mechanism between the host and the guest. It's somewhat like TCP over VMBus, but the transportation layer (VMBus) is much simpler than IP.
With Hyper-V Sockets, applications between the host and the guest can talk to each other directly by the traditional BSD-style socket APIs. Hyper-V Sockets is only available on new Windows hosts, like Windows Server 2016. More info is in this article "Make your own integration services": https://msdn.microsoft.com/en-us/virtualization/hyperv_on_windows/develop/make_mgmt_service The patch implements the necessary support in the guest side by introducing a new socket address family AF_HYPERV. You can also get the patch by (commit 84146dfb): https://github.com/dcui/linux/commits/decui/hv_sock/net-next/20160721_v18 Note: the VMBus driver side's supporting patches have been in the mainline tree. I know the kernel has already had a VM Sockets driver (AF_VSOCK) based on VMware VMCI (net/vmw_vsock/, drivers/misc/vmw_vmci), and KVM is proposing AF_VSOCK of virtio version: http://marc.info/?l=linux-netdev&m=145952064004765&w=2 However, though Hyper-V Sockets may seem conceptually similar to AF_VOSCK, there are differences in the transportation layer, and IMO these make the direct code reusing impractical: 1. In AF_VSOCK, the endpoint type is: <u32 ContextID, u32 Port>, but in AF_HYPERV, the endpoint type is: <GUID VM_ID, GUID ServiceID>. Here GUID is 128-bit. 2. AF_VSOCK supports SOCK_DGRAM, while AF_HYPERV doesn't. 3. AF_VSOCK supports some special sock opts, like SO_VM_SOCKETS_BUFFER_SIZE, SO_VM_SOCKETS_BUFFER_MIN/MAX_SIZE and SO_VM_SOCKETS_CONNECT_TIMEOUT. These are meaningless to AF_HYPERV. 4. Some AF_VSOCK's VMCI transportation ops are meanless to AF_HYPERV/VMBus, like .notify_recv_init .notify_recv_pre_block .notify_recv_pre_dequeue .notify_recv_post_dequeue .notify_send_init .notify_send_pre_block .notify_send_pre_enqueue .notify_send_post_enqueue etc. So I think we'd better introduce a new address family: AF_HYPERV. Please review the patch. Looking forward to your comments, especially comments from David. :-) Changes since v1: - updated "[PATCH 6/7] hvsock: introduce Hyper-V VM Sockets feature" - added __init and __exit for the module init/exit functions - net/hv_sock/Kconfig: "default m" -> "default m if HYPERV" - MODULE_LICENSE: "Dual MIT/GPL" -> "Dual BSD/GPL" Changes since v2: - fixed various coding issue pointed out by David Miller - fixed indentation issues - removed pr_debug in net/hv_sock/af_hvsock.c - used reverse-Chrismas-tree style for local variables. - EXPORT_SYMBOL -> EXPORT_SYMBOL_GPL Changes since v3: - fixed a few coding issue pointed by Vitaly Kuznetsov and Dan Carpenter - fixed the ret value in vmbus_recvpacket_hvsock on error - fixed the style of multi-line comment: vmbus_get_hvsock_rw_status() Changes since v4 (https://lkml.org/lkml/2015/7/28/404): - addressed all the comments about V4. - treat the hvsock offers/channels as special VMBus devices - add a mechanism to pass hvsock events to the hvsock driver - fixed some corner cases with proper locking when a connection is closed - rebased to the latest Greg's tree Changes since v5 (https://lkml.org/lkml/2015/12/24/103): - addressed the coding style issues (Vitaly Kuznetsov & David Miller, thanks!) - used a better coding for the per-channel rescind callback (Thank Vitaly!) - avoided the introduction of new VMBUS driver APIs vmbus_sendpacket_hvsock() and vmbus_recvpacket_hvsock() and used vmbus_sendpacket()/vmbus_recvpacket() in the higher level (i.e., the vmsock driver). Thank Vitaly! Changes since v6 (http://lkml.iu.edu/hypermail/linux/kernel/1601.3/01813.html) - only a few minor changes of coding style and comments Changes since v7 - a few minor changes of coding style: thanks, Joe Perches! - added some lines of comments about GUID/UUID before the struct sockaddr_hv. Changes since v8 - removed the unnecessary __packed for some definitions: thanks, David! - hvsock_open_connection: use offer.u.pipe.user_def[0] to know the connection and reorganized the function direction - reorganized the code according to suggestions from Cathy Avery: split big functions into small ones, set .setsockopt and getsockopt to sock_no_setsockopt/sock_no_getsockopt - inline'd some small list helper functions Changes since v9 - minimized struct hvsock_sock by making the send/recv buffers pointers. the buffers are allocated by kmalloc() in __hvsock_create() now. - minimized the sizes of the send/recv buffers and the vmbus ringbuffers. Changes since v10 1) add module params: send_ring_page, recv_ring_page. They can be used to enlarge the ringbuffer size to get better performance, e.g., # modprobe hv_sock recv_ring_page=16 send_ring_page=16 By default, recv_ring_page is 3 and send_ring_page is 2. 2) add module param max_socket_number (the default is 1024). A user can enlarge the number to create more than 1024 hv_sock sockets. By default, 1024 sockets take about 1024 * (3+2+1+1) * 4KB = 28M bytes. (Here 1+1 means 1 page for send/recv buffers per connection, respectively.) 3) implement the TODO in hvsock_shutdown(). 4) fix a bug in hvsock_close_connection(): I remove "sk->sk_socket->state = SS_UNCONNECTED;" -- actually this line is not really useful. For a connection triggered by a host app's connect(), sk->sk_socket remains NULL before the connection is accepted by the server app (in Linux VM): see hvsock_accept() -> hvsock_accept_wait() -> sock_graft(connected, newsock). If the host app exits before the server app's accept() returns, the host can send a rescind-message to close the connection and later in the Linux VM's message handler i.e. vmbus_onoffer_rescind()), Linux will get a NULL de-referencing crash. 5) fix a bug in hvsock_open_connection() I move the vmbus_set_chn_rescind_callback() to a later place, because when vmbus_open() fails, hvsock_close_connection() can do nothing and we count on vmbus_onoffer_rescind() -> vmbus_device_unregister() to clean up the device. 6) some stylistic modificiation. Changes since v11: 1) remove the module params as David suggested. 2) use 5 exact pages for VMBus send/recv rings, respectively. The host side's design of the feature requires 5 exact pages for recv/send rings respectively -- this is suboptimal considering memory consumption, however unluckily we have to live with it, before the host comes up with a new design in the future. :-( 3) remove the per-connection static send/recv buffers Instead, we allocate and free the buffers dynamically only when we recv/send data. This means: when a connection is idle, no memory is consumed as recv/send buffers at all. Dexuan Cui (1): hv_sock: introduce Hyper-V Sockets Changes since v12: return ENOMEM on buffer alllocation failure Actually "man read/write" says "Other errors may occur, depending on the object connected to fd". "man send/recv" indeed lists ENOMEM. Considering AF_HYPERV is a new socket type, ENOMEM seems OK here. In the long run, I think we should add a new API in the VMBus driver, allowing data copy from VMBus ringbuffer into user mode buffer directly. This way, we can even eliminate this temporary buffer. Changes since v13: fix some coding style issues pointed out by David. Changes since v14: Just some stylistic changes addressing comments from Joe Perches and Olaf Hering -- thank you! - add a GPL blurb. - define a new macro PAGE_SIZE_4K and use it to replace PAGE_SIZE - change sk_to_hvsock/hvsock_to_sk() from macros to inline functions - remove a not-very-useful pr_err() - fix some typos in comment and coding style issues. Changes since v15: Made stylistic changes addressing comments from Vitaly Kuznetsov. Thank you very much for the detailed comments, Vitaly! Changes since v16: - PAGE_SIZE -> PAGE_SIZE_4K - allow regular users to use the socket Thank you Michal Kubecek for the suggestions! Changes since v17: Just some tiny updates to address some spurious compiler warnings: "xxx may be used uninitialized in this function". Dexuan Cui (1): hv_sock: introduce Hyper-V Sockets MAINTAINERS | 2 + include/linux/hyperv.h | 13 + include/linux/socket.h | 4 +- include/net/af_hvsock.h | 78 +++ include/uapi/linux/hyperv.h | 23 + net/Kconfig | 1 + net/Makefile | 1 + net/hv_sock/Kconfig | 10 + net/hv_sock/Makefile | 3 + net/hv_sock/af_hvsock.c | 1507 +++++++++++++++++++++++++++++++++++++++++++ 10 files changed, 1641 insertions(+), 1 deletion(-) create mode 100644 include/net/af_hvsock.h create mode 100644 net/hv_sock/Kconfig create mode 100644 net/hv_sock/Makefile create mode 100644 net/hv_sock/af_hvsock.c -- 2.1.0
