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|
/*
* Hyper-V transport for vsock
*
* Hyper-V Sockets supplies a byte-stream based communication mechanism
* between the host and the VM. This driver implements the necessary
* support in the VM by introducing the new vsock transport.
*
* Copyright (c) 2017, Microsoft Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
*/
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/hyperv.h>
#include <net/sock.h>
#include <net/af_vsock.h>
/* The host side's design of the feature requires 6 exact 4KB 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 better design in the future.
*/
#define PAGE_SIZE_4K 4096
#define RINGBUFFER_HVS_RCV_SIZE (PAGE_SIZE_4K * 6)
#define RINGBUFFER_HVS_SND_SIZE (PAGE_SIZE_4K * 6)
/* The MTU is 16KB per the host side's design */
#define HVS_MTU_SIZE (1024 * 16)
struct vmpipe_proto_header {
u32 pkt_type;
u32 data_size;
};
/* For recv, we use the VMBus in-place packet iterator APIs to directly copy
* data from the ringbuffer into the userspace buffer.
*/
struct hvs_recv_buf {
/* The header before the payload data */
struct vmpipe_proto_header hdr;
/* The payload */
u8 data[HVS_MTU_SIZE];
};
/* We can send up to HVS_MTU_SIZE bytes of payload to the host, but let's use
* a small size, i.e. HVS_SEND_BUF_SIZE, to minimize the dynamically-allocated
* buffer, because tests show there is no significant performance difference.
*
* Note: the buffer can be eliminated in the future when we add new VMBus
* ringbuffer APIs that allow us to directly copy data from userspace buffer
* to VMBus ringbuffer.
*/
#define HVS_SEND_BUF_SIZE (PAGE_SIZE_4K - sizeof(struct vmpipe_proto_header))
struct hvs_send_buf {
/* The header before the payload data */
struct vmpipe_proto_header hdr;
/* The payload */
u8 data[HVS_SEND_BUF_SIZE];
};
#define HVS_HEADER_LEN (sizeof(struct vmpacket_descriptor) + \
sizeof(struct vmpipe_proto_header))
/* See 'prev_indices' in hv_ringbuffer_read(), hv_ringbuffer_write(), and
* __hv_pkt_iter_next().
*/
#define VMBUS_PKT_TRAILER_SIZE (sizeof(u64))
#define HVS_PKT_LEN(payload_len) (HVS_HEADER_LEN + \
ALIGN((payload_len), 8) + \
VMBUS_PKT_TRAILER_SIZE)
union hvs_service_id {
uuid_le srv_id;
struct {
unsigned int svm_port;
unsigned char b[sizeof(uuid_le) - sizeof(unsigned int)];
};
};
/* Per-socket state (accessed via vsk->trans) */
struct hvsock {
struct vsock_sock *vsk;
uuid_le vm_srv_id;
uuid_le host_srv_id;
struct vmbus_channel *chan;
struct vmpacket_descriptor *recv_desc;
/* The length of the payload not delivered to userland yet */
u32 recv_data_len;
/* The offset of the payload */
u32 recv_data_off;
/* Have we sent the zero-length packet (FIN)? */
bool fin_sent;
};
/* In the VM, we support Hyper-V Sockets with AF_VSOCK, and the endpoint is
* <cid, port> (see struct sockaddr_vm). Note: cid is not really used here:
* when we write apps to connect to the host, we can only use VMADDR_CID_ANY
* or VMADDR_CID_HOST (both are equivalent) as the remote cid, and when we
* write apps to bind() & listen() in the VM, we can only use VMADDR_CID_ANY
* as the local cid.
*
* On the host, Hyper-V Sockets are supported by Winsock AF_HYPERV:
* https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/user-
* guide/make-integration-service, and the endpoint is <VmID, ServiceId> with
* the below sockaddr:
*
* struct SOCKADDR_HV
* {
* ADDRESS_FAMILY Family;
* USHORT Reserved;
* GUID VmId;
* GUID ServiceId;
* };
* Note: VmID is not used by Linux VM and actually it isn't transmitted via
* VMBus, because here it's obvious the host and the VM can easily identify
* each other. Though the VmID is useful on the host, especially in the case
* of Windows container, Linux VM doesn't need it at all.
*
* To make use of the AF_VSOCK infrastructure in Linux VM, we have to limit
* the available GUID space of SOCKADDR_HV so that we can create a mapping
* between AF_VSOCK port and SOCKADDR_HV Service GUID. The rule of writing
* Hyper-V Sockets apps on the host and in Linux VM is:
*
****************************************************************************
* The only valid Service GUIDs, from the perspectives of both the host and *
* Linux VM, that can be connected by the other end, must conform to this *
* format: <port>-facb-11e6-bd58-64006a7986d3, and the "port" must be in *
* this range [0, 0x7FFFFFFF]. *
****************************************************************************
*
* When we write apps on the host to connect(), the GUID ServiceID is used.
* When we write apps in Linux VM to connect(), we only need to specify the
* port and the driver will form the GUID and use that to request the host.
*
* From the perspective of Linux VM:
* 1. the local ephemeral port (i.e. the local auto-bound port when we call
* connect() without explicit bind()) is generated by __vsock_bind_stream(),
* and the range is [1024, 0xFFFFFFFF).
* 2. the remote ephemeral port (i.e. the auto-generated remote port for
* a connect request initiated by the host's connect()) is generated by
* hvs_remote_addr_init() and the range is [0x80000000, 0xFFFFFFFF).
*/
#define MAX_LISTEN_PORT ((u32)0x7FFFFFFF)
#define MAX_VM_LISTEN_PORT MAX_LISTEN_PORT
#define MAX_HOST_LISTEN_PORT MAX_LISTEN_PORT
#define MIN_HOST_EPHEMERAL_PORT (MAX_HOST_LISTEN_PORT + 1)
/* 00000000-facb-11e6-bd58-64006a7986d3 */
static const uuid_le srv_id_template =
UUID_LE(0x00000000, 0xfacb, 0x11e6, 0xbd, 0x58,
0x64, 0x00, 0x6a, 0x79, 0x86, 0xd3);
static bool is_valid_srv_id(const uuid_le *id)
{
return !memcmp(&id->b[4], &srv_id_template.b[4], sizeof(uuid_le) - 4);
}
static unsigned int get_port_by_srv_id(const uuid_le *svr_id)
{
return *((unsigned int *)svr_id);
}
static void hvs_addr_init(struct sockaddr_vm *addr, const uuid_le *svr_id)
{
unsigned int port = get_port_by_srv_id(svr_id);
vsock_addr_init(addr, VMADDR_CID_ANY, port);
}
static void hvs_remote_addr_init(struct sockaddr_vm *remote,
struct sockaddr_vm *local)
{
static u32 host_ephemeral_port = MIN_HOST_EPHEMERAL_PORT;
struct sock *sk;
vsock_addr_init(remote, VMADDR_CID_ANY, VMADDR_PORT_ANY);
while (1) {
/* Wrap around ? */
if (host_ephemeral_port < MIN_HOST_EPHEMERAL_PORT ||
host_ephemeral_port == VMADDR_PORT_ANY)
host_ephemeral_port = MIN_HOST_EPHEMERAL_PORT;
remote->svm_port = host_ephemeral_port++;
sk = vsock_find_connected_socket(remote, local);
if (!sk) {
/* Found an available ephemeral port */
return;
}
/* Release refcnt got in vsock_find_connected_socket */
sock_put(sk);
}
}
static void hvs_set_channel_pending_send_size(struct vmbus_channel *chan)
{
set_channel_pending_send_size(chan,
HVS_PKT_LEN(HVS_SEND_BUF_SIZE));
/* See hvs_stream_has_space(): we must make sure the host has seen
* the new pending send size, before we can re-check the writable
* bytes.
*/
virt_mb();
}
static void hvs_clear_channel_pending_send_size(struct vmbus_channel *chan)
{
set_channel_pending_send_size(chan, 0);
/* Ditto */
virt_mb();
}
static bool hvs_channel_readable(struct vmbus_channel *chan)
{
u32 readable = hv_get_bytes_to_read(&chan->inbound);
/* 0-size payload means FIN */
return readable >= HVS_PKT_LEN(0);
}
static int hvs_channel_readable_payload(struct vmbus_channel *chan)
{
u32 readable = hv_get_bytes_to_read(&chan->inbound);
if (readable > HVS_PKT_LEN(0)) {
/* At least we have 1 byte to read. We don't need to return
* the exact readable bytes: see vsock_stream_recvmsg() ->
|