Re: [PATCH 19/24] vhost-user: introduce vhost-user API

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Feb 02, 2024 at 03:11:46PM +0100, Laurent Vivier wrote:
> Add vhost_user.c and vhost_user.h that define the functions needed
> to implement vhost-user backend.
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  Makefile     |    4 +-
>  passt.c      |    2 +
>  passt.h      |    8 +
>  tap.c        |    2 +-
>  tap.h        |    3 +
>  vhost_user.c | 1050 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  vhost_user.h |  139 +++++++
>  7 files changed, 1205 insertions(+), 3 deletions(-)
>  create mode 100644 vhost_user.c
>  create mode 100644 vhost_user.h
> 
> diff --git a/Makefile b/Makefile
> index ae1daa6b2b50..2016b071ddf2 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -47,7 +47,7 @@ FLAGS += -DDUAL_STACK_SOCKETS=$(DUAL_STACK_SOCKETS)
>  PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c flow.c icmp.c \
>  	igmp.c isolation.c lineread.c log.c mld.c ndp.c netlink.c packet.c \
>  	passt.c pasta.c pcap.c pif.c port_fwd.c tap.c tcp.c tcp_splice.c \
> -	tcp_buf.c udp.c util.c iov.c ip.c virtio.c
> +	tcp_buf.c udp.c util.c iov.c ip.c virtio.c vhost_user.c
>  QRAP_SRCS = qrap.c
>  SRCS = $(PASST_SRCS) $(QRAP_SRCS)
>  
> @@ -57,7 +57,7 @@ PASST_HEADERS = arch.h arp.h checksum.h conf.h dhcp.h dhcpv6.h flow.h \
>  	flow_table.h icmp.h inany.h isolation.h lineread.h log.h ndp.h \
>  	netlink.h packet.h passt.h pasta.h pcap.h pif.h port_fwd.h siphash.h \
>  	tap.h tcp.h tcp_conn.h tcp_splice.h tcp_buf.h tcp_internal.h udp.h \
> -	util.h iov.h ip.h virtio.h
> +	util.h iov.h ip.h virtio.h vhost_user.h
>  HEADERS = $(PASST_HEADERS) seccomp.h
>  
>  C := \#include <linux/tcp.h>\nstruct tcp_info x = { .tcpi_snd_wnd = 0 };
> diff --git a/passt.c b/passt.c
> index 5056a49dec95..95034d73381f 100644
> --- a/passt.c
> +++ b/passt.c
> @@ -72,6 +72,8 @@ char *epoll_type_str[] = {
>  	[EPOLL_TYPE_TAP_PASTA]	= "/dev/net/tun device",
>  	[EPOLL_TYPE_TAP_PASST]	= "connected qemu socket",
>  	[EPOLL_TYPE_TAP_LISTEN]	= "listening qemu socket",
> +	[EPOLL_TYPE_VHOST_CMD]	= "vhost-user command socket",
> +	[EPOLL_TYPE_VHOST_KICK]	= "vhost-user kick socket",
>  };
>  static_assert(ARRAY_SIZE(epoll_type_str) == EPOLL_NUM_TYPES,
>  	      "epoll_type_str[] doesn't match enum epoll_type");
> diff --git a/passt.h b/passt.h
> index a9e8f15af0e1..6ed1d0b19e82 100644
> --- a/passt.h
> +++ b/passt.h
> @@ -42,6 +42,7 @@ union epoll_ref;
>  #include "port_fwd.h"
>  #include "tcp.h"
>  #include "udp.h"
> +#include "vhost_user.h"
>  
>  /**
>   * enum epoll_type - Different types of fds we poll over
> @@ -71,6 +72,10 @@ enum epoll_type {
>  	EPOLL_TYPE_TAP_PASST,
>  	/* socket listening for qemu socket connections */
>  	EPOLL_TYPE_TAP_LISTEN,
> +	/* vhost-user command socket */
> +	EPOLL_TYPE_VHOST_CMD,
> +	/* vhost-user kick event socket */
> +	EPOLL_TYPE_VHOST_KICK,
>  
>  	EPOLL_NUM_TYPES,
>  };
> @@ -303,6 +308,9 @@ struct ctx {
>  
>  	int low_wmem;
>  	int low_rmem;
> +
> +	/* vhost-user */
> +	struct VuDev vdev;
>  };
>  
>  void proto_update_l2_buf(const unsigned char *eth_d,
> diff --git a/tap.c b/tap.c
> index ebe52247ad87..936206e53637 100644
> --- a/tap.c
> +++ b/tap.c
> @@ -954,7 +954,7 @@ void packet_add_all_do(struct ctx *c, ssize_t len, char *p,
>   * tap_sock_reset() - Handle closing or failure of connect AF_UNIX socket
>   * @c:		Execution context
>   */
> -static void tap_sock_reset(struct ctx *c)
> +void tap_sock_reset(struct ctx *c)
>  {
>  	if (c->one_off) {
>  		info("Client closed connection, exiting");
> diff --git a/tap.h b/tap.h
> index 7157ef37ee6e..ee839d4f09dc 100644
> --- a/tap.h
> +++ b/tap.h
> @@ -81,12 +81,15 @@ void tap_handler_pasta(struct ctx *c, uint32_t events,
>  		       const struct timespec *now);
>  void tap_handler_passt(struct ctx *c, uint32_t events,
>  		       const struct timespec *now);
> +void tap_sock_reset(struct ctx *c);
>  void tap_sock_init(struct ctx *c);
>  void pool_flush_all(void);
>  void tap_handler_all(struct ctx *c, const struct timespec *now);
>  
>  void packet_add_do(struct pool *p, size_t len, const char *start,
>  		   const char *func, int line);
> +void packet_add_all_do(struct ctx *c, ssize_t len, char *p,
> +		       const char *func, int line);

This looks like it should be a fixup for the earlier patch which
introduced the macro below.

>  #define packet_add_all(p, len, start)					\
>  	packet_add_all_do(p, len, start, __func__, __LINE__)
>  
> diff --git a/vhost_user.c b/vhost_user.c
> new file mode 100644
> index 000000000000..2acd72398e3a
> --- /dev/null
> +++ b/vhost_user.c
> @@ -0,0 +1,1050 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +
> +/* some parts from QEMU subprojects/libvhost-user/libvhost-user.c */
> +
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <stdint.h>
> +#include <stddef.h>
> +#include <string.h>
> +#include <assert.h>
> +#include <stdbool.h>
> +#include <inttypes.h>
> +#include <time.h>
> +#include <net/ethernet.h>
> +#include <netinet/in.h>
> +#include <sys/epoll.h>
> +#include <sys/eventfd.h>
> +#include <sys/mman.h>
> +#include <linux/vhost_types.h>
> +#include <linux/virtio_net.h>
> +
> +#include "util.h"
> +#include "passt.h"
> +#include "tap.h"
> +#include "vhost_user.h"
> +
> +#define VHOST_USER_VERSION 1
> +
> +static unsigned char buffer[65536][VHOST_USER_MAX_QUEUES];
> +
> +void vu_print_capabilities(void)
> +{
> +	printf("{\n");
> +	printf("  \"type\": \"net\"\n");
> +	printf("}\n");
> +	exit(EXIT_SUCCESS);

It's not clear to me what we need this for.

> +}
> +
> +static const char *
> +vu_request_to_string(unsigned int req)
> +{
> +#define REQ(req) [req] = #req
> +	static const char *vu_request_str[] = {
> +		REQ(VHOST_USER_NONE),
> +		REQ(VHOST_USER_GET_FEATURES),
> +		REQ(VHOST_USER_SET_FEATURES),
> +		REQ(VHOST_USER_SET_OWNER),
> +		REQ(VHOST_USER_RESET_OWNER),
> +		REQ(VHOST_USER_SET_MEM_TABLE),
> +		REQ(VHOST_USER_SET_LOG_BASE),
> +		REQ(VHOST_USER_SET_LOG_FD),
> +		REQ(VHOST_USER_SET_VRING_NUM),
> +		REQ(VHOST_USER_SET_VRING_ADDR),
> +		REQ(VHOST_USER_SET_VRING_BASE),
> +		REQ(VHOST_USER_GET_VRING_BASE),
> +		REQ(VHOST_USER_SET_VRING_KICK),
> +		REQ(VHOST_USER_SET_VRING_CALL),
> +		REQ(VHOST_USER_SET_VRING_ERR),
> +		REQ(VHOST_USER_GET_PROTOCOL_FEATURES),
> +		REQ(VHOST_USER_SET_PROTOCOL_FEATURES),
> +		REQ(VHOST_USER_GET_QUEUE_NUM),
> +		REQ(VHOST_USER_SET_VRING_ENABLE),
> +		REQ(VHOST_USER_SEND_RARP),
> +		REQ(VHOST_USER_NET_SET_MTU),
> +		REQ(VHOST_USER_SET_BACKEND_REQ_FD),
> +		REQ(VHOST_USER_IOTLB_MSG),
> +		REQ(VHOST_USER_SET_VRING_ENDIAN),
> +		REQ(VHOST_USER_GET_CONFIG),
> +		REQ(VHOST_USER_SET_CONFIG),
> +		REQ(VHOST_USER_POSTCOPY_ADVISE),
> +		REQ(VHOST_USER_POSTCOPY_LISTEN),
> +		REQ(VHOST_USER_POSTCOPY_END),
> +		REQ(VHOST_USER_GET_INFLIGHT_FD),
> +		REQ(VHOST_USER_SET_INFLIGHT_FD),
> +		REQ(VHOST_USER_GPU_SET_SOCKET),
> +		REQ(VHOST_USER_VRING_KICK),
> +		REQ(VHOST_USER_GET_MAX_MEM_SLOTS),
> +		REQ(VHOST_USER_ADD_MEM_REG),
> +		REQ(VHOST_USER_REM_MEM_REG),
> +		REQ(VHOST_USER_MAX),
> +	};
> +#undef REQ
> +
> +	if (req < VHOST_USER_MAX) {
> +		return vu_request_str[req];
> +	} else {
> +		return "unknown";
> +	}
> +}
> +
> +/* Translate qemu virtual address to our virtual address.  */

The meaning of this comment in its new context is rather unclear.

> +static void *qva_to_va(VuDev *dev, uint64_t qemu_addr)
> +{
> +	unsigned int i;
> +
> +	/* Find matching memory region.  */
> +	for (i = 0; i < dev->nregions; i++) {
> +		VuDevRegion *r = &dev->regions[i];
> +
> +		if ((qemu_addr >= r->qva) && (qemu_addr < (r->qva + r->size))) {
> +			return (void *)(uintptr_t)
> +			(qemu_addr - r->qva + r->mmap_addr + r->mmap_offset);
> +		}
> +	}
> +
> +	return NULL;
> +}
> +
> +static void
> +vmsg_close_fds(VhostUserMsg *vmsg)
> +{
> +	int i;
> +
> +	for (i = 0; i < vmsg->fd_num; i++)
> +		close(vmsg->fds[i]);
> +}
> +
> +static void vu_remove_watch(VuDev *vdev, int fd)
> +{
> +	struct ctx *c = (struct ctx *) ((char *)vdev - offsetof(struct ctx, vdev));
> +
> +	epoll_ctl(c->epollfd, EPOLL_CTL_DEL, fd, NULL);
> +}
> +
> +/* Set reply payload.u64 and clear request flags and fd_num */
> +static void vmsg_set_reply_u64(struct VhostUserMsg *vmsg, uint64_t val)
> +{
> +	vmsg->hdr.flags = 0; /* defaults will be set by vu_send_reply() */
> +	vmsg->hdr.size = sizeof(vmsg->payload.u64);
> +	vmsg->payload.u64 = val;
> +	vmsg->fd_num = 0;
> +}
> +
> +static ssize_t vu_message_read_default(VuDev *dev, int conn_fd, struct VhostUserMsg *vmsg)

This only appears to return 0, 1 or a negative errno, which makes
ssize_t an odd choice.

> +{
> +	char control[CMSG_SPACE(VHOST_MEMORY_BASELINE_NREGIONS *
> +		     sizeof(int))] = { 0 };
> +	struct iovec iov = {
> +		.iov_base = (char *)vmsg,
> +		.iov_len = VHOST_USER_HDR_SIZE,
> +	};
> +	struct msghdr msg = {
> +		.msg_iov = &iov,
> +		.msg_iovlen = 1,
> +		.msg_control = control,
> +		.msg_controllen = sizeof(control),
> +	};
> +	size_t fd_size;
> +	struct cmsghdr *cmsg;
> +	ssize_t ret, sz_payload;
> +
> +	ret = recvmsg(conn_fd, &msg, MSG_DONTWAIT);
> +	if (ret < 0) {
> +		if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
> +			return 0;
> +		vu_panic(dev, "Error while recvmsg: %s", strerror(errno));
> +		goto out;
> +	}
> +
> +	vmsg->fd_num = 0;
> +	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
> +	     cmsg = CMSG_NXTHDR(&msg, cmsg)) {
> +		if (cmsg->cmsg_level == SOL_SOCKET &&
> +		    cmsg->cmsg_type == SCM_RIGHTS) {
> +			fd_size = cmsg->cmsg_len - CMSG_LEN(0);
> +			vmsg->fd_num = fd_size / sizeof(int);
> +			memcpy(vmsg->fds, CMSG_DATA(cmsg), fd_size);
> +			break;
> +		}
> +	}
> +
> +	sz_payload = vmsg->hdr.size;
> +	if ((size_t)sz_payload > sizeof(vmsg->payload)) {
> +		vu_panic(dev,
> +			 "Error: too big message request: %d, size: vmsg->size: %zd, "
> +			 "while sizeof(vmsg->payload) = %zu",
> +			 vmsg->hdr.request, sz_payload, sizeof(vmsg->payload));
> +		goto out;
> +	}
> +
> +	if (sz_payload) {
> +		do {
> +			ret = recv(conn_fd, &vmsg->payload, sz_payload, 0);
> +		} while (ret < 0 && (errno == EINTR || errno == EAGAIN));
> +
> +		if (ret < sz_payload) {
> +			vu_panic(dev, "Error while reading: %s", strerror(errno));
> +			goto out;
> +		}
> +	}
> +
> +	return 1;
> +out:
> +	vmsg_close_fds(vmsg);
> +
> +	return -ECONNRESET;
> +}
> +
> +static int vu_message_write(VuDev *dev, int conn_fd, struct VhostUserMsg *vmsg)
> +{
> +	int rc;
> +	uint8_t *p = (uint8_t *)vmsg;
> +	char control[CMSG_SPACE(VHOST_MEMORY_BASELINE_NREGIONS * sizeof(int))] = { 0 };
> +	struct iovec iov = {
> +		.iov_base = (char *)vmsg,
> +		.iov_len = VHOST_USER_HDR_SIZE,
> +	};
> +	struct msghdr msg = {
> +		.msg_iov = &iov,
> +		.msg_iovlen = 1,
> +		.msg_control = control,
> +	};
> +	struct cmsghdr *cmsg;
> +
> +	memset(control, 0, sizeof(control));

Redudant with the initializer AFAICT.

> +	assert(vmsg->fd_num <= VHOST_MEMORY_BASELINE_NREGIONS);
> +	if (vmsg->fd_num > 0) {
> +		size_t fdsize = vmsg->fd_num * sizeof(int);
> +		msg.msg_controllen = CMSG_SPACE(fdsize);
> +		cmsg = CMSG_FIRSTHDR(&msg);
> +		cmsg->cmsg_len = CMSG_LEN(fdsize);
> +		cmsg->cmsg_level = SOL_SOCKET;
> +		cmsg->cmsg_type = SCM_RIGHTS;
> +		memcpy(CMSG_DATA(cmsg), vmsg->fds, fdsize);
> +	} else {
> +		msg.msg_controllen = 0;
> +	}
> +
> +	do {
> +		rc = sendmsg(conn_fd, &msg, 0);
> +	} while (rc < 0 && (errno == EINTR || errno == EAGAIN));

Hrm.. if this first sendmsg() returns a (non EINTER, non EGAIN) error,
couldn't the sending of the payload clobber rc before we actually
handle it and print an error?

> +	if (vmsg->hdr.size) {
> +		do {
> +			if (vmsg->data) {
> +				rc = write(conn_fd, vmsg->data, vmsg->hdr.size);
> +			} else {
> +				rc = write(conn_fd, p + VHOST_USER_HDR_SIZE, vmsg->hdr.size);
> +			}
> +		} while (rc < 0 && (errno == EINTR || errno == EAGAIN));
> +	}
> +
> +	if (rc <= 0) {
> +		vu_panic(dev, "Error while writing: %s", strerror(errno));
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
> +static int vu_send_reply(VuDev *dev, int conn_fd, struct VhostUserMsg *msg)
> +{
> +	msg->hdr.flags &= ~VHOST_USER_VERSION_MASK;
> +	msg->hdr.flags |= VHOST_USER_VERSION;
> +	msg->hdr.flags |= VHOST_USER_REPLY_MASK;
> +
> +	return vu_message_write(dev, conn_fd, msg);
> +}
> +
> +static bool vu_get_features_exec(struct VhostUserMsg *msg)
> +{
> +	uint64_t features =
> +		1ULL << VIRTIO_F_VERSION_1 |
> +		1ULL << VIRTIO_NET_F_MRG_RXBUF |
> +		1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
> +
> +	vmsg_set_reply_u64(msg, features);
> +
> +	debug("Sending back to guest u64: 0x%016"PRIx64, msg->payload.u64);
> +
> +	return true;
> +}
> +
> +static void
> +vu_set_enable_all_rings(VuDev *vdev, bool enabled)
> +{
> +	uint16_t i;
> +
> +	for (i = 0; i < VHOST_USER_MAX_QUEUES; i++) {
> +		vdev->vq[i].enable = enabled;
> +	}
> +}
> +
> +static bool
> +vu_set_features_exec(VuDev *vdev, struct VhostUserMsg *msg)
> +{
> +	debug("u64: 0x%016"PRIx64, msg->payload.u64);

I think a lot of these debug messages need some looking over to make
sure they're actually clear if you don't already know they're related
to vhost-user.

> +
> +	vdev->features = msg->payload.u64;
> +	if (!vu_has_feature(vdev, VIRTIO_F_VERSION_1)) {
> +		/*
> +		 * We only support devices conforming to VIRTIO 1.0 or
> +		 * later
> +		 */
> +		vu_panic(vdev, "virtio legacy devices aren't supported by passt");
> +		return false;
> +	}
> +
> +	if (!vu_has_feature(vdev, VHOST_USER_F_PROTOCOL_FEATURES)) {
> +		vu_set_enable_all_rings(vdev, true);
> +	}
> +
> +	/* virtio-net features */
> +
> +	if (vu_has_feature(vdev, VIRTIO_F_VERSION_1) ||

Won't this always be true given the test above?

> +	    vu_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF)) {
> +		vdev->hdrlen = sizeof(struct virtio_net_hdr_mrg_rxbuf);
> +	} else {
> +		vdev->hdrlen = sizeof(struct virtio_net_hdr);
> +	}
> +
> +	return false;
> +}
> +
> +static bool
> +vu_set_owner_exec(void)
> +{
> +	return false;
> +}
> +
> +static bool map_ring(VuDev *vdev, VuVirtq *vq)
> +{
> +	vq->vring.desc = qva_to_va(vdev, vq->vra.desc_user_addr);
> +	vq->vring.used = qva_to_va(vdev, vq->vra.used_user_addr);
> +	vq->vring.avail = qva_to_va(vdev, vq->vra.avail_user_addr);
> +
> +	debug("Setting virtq addresses:");
> +	debug("    vring_desc  at %p", (void *)vq->vring.desc);
> +	debug("    vring_used  at %p", (void *)vq->vring.used);
> +	debug("    vring_avail at %p", (void *)vq->vring.avail);
> +
> +	return !(vq->vring.desc && vq->vring.used && vq->vring.avail);
> +}
> +
> +/*
> + * #syscalls:passt mmap munmap
> + */
> +
> +static bool vu_set_mem_table_exec(VuDev *vdev,
> +				  struct VhostUserMsg *msg)
> +{
> +	unsigned int i;
> +	struct VhostUserMemory m = msg->payload.memory, *memory = &m;
> +
> +	for (i = 0; i < vdev->nregions; i++) {
> +		VuDevRegion *r = &vdev->regions[i];
> +		void *m = (void *) (uintptr_t) r->mmap_addr;
> +
> +		if (m)
> +			munmap(m, r->size + r->mmap_offset);
> +	}
> +	vdev->nregions = memory->nregions;
> +
> +	debug("Nregions: %u", memory->nregions);
> +	for (i = 0; i < vdev->nregions; i++) {
> +		void *mmap_addr;
> +		VhostUserMemory_region *msg_region = &memory->regions[i];
> +		VuDevRegion *dev_region = &vdev->regions[i];
> +
> +		debug("Region %d", i);
> +		debug("    guest_phys_addr: 0x%016"PRIx64,
> +		      msg_region->guest_phys_addr);
> +		debug("    memory_size:     0x%016"PRIx64,
> +		      msg_region->memory_size);
> +		debug("    userspace_addr   0x%016"PRIx64,
> +		      msg_region->userspace_addr);
> +		debug("    mmap_offset      0x%016"PRIx64,
> +		      msg_region->mmap_offset);
> +
> +		dev_region->gpa = msg_region->guest_phys_addr;
> +		dev_region->size = msg_region->memory_size;
> +		dev_region->qva = msg_region->userspace_addr;
> +		dev_region->mmap_offset = msg_region->mmap_offset;
> +
> +		/* We don't use offset argument of mmap() since the
> +		 * mapped address has to be page aligned, and we use huge
> +		 * pages.  */

Is that accurate in the new context?

> +		mmap_addr = mmap(0, dev_region->size + dev_region->mmap_offset,
> +				 PROT_READ | PROT_WRITE, MAP_SHARED | MAP_NORESERVE,
> +				 msg->fds[i], 0);
> +
> +		if (mmap_addr == MAP_FAILED) {
> +			vu_panic(vdev, "region mmap error: %s", strerror(errno));
> +		} else {
> +			dev_region->mmap_addr = (uint64_t)(uintptr_t)mmap_addr;
> +			debug("    mmap_addr:       0x%016"PRIx64,
> +			      dev_region->mmap_addr);
> +		}
> +
> +		close(msg->fds[i]);
> +	}
> +
> +	for (i = 0; i < VHOST_USER_MAX_QUEUES; i++) {
> +		if (vdev->vq[i].vring.desc) {
> +			if (map_ring(vdev, &vdev->vq[i])) {
> +				vu_panic(vdev, "remapping queue %d during setmemtable", i);
> +			}
> +		}
> +	}
> +
> +	return false;
> +}
> +
> +static bool vu_set_vring_num_exec(VuDev *vdev,
> +				  struct VhostUserMsg *msg)
> +{
> +	unsigned int index = msg->payload.state.index;
> +	unsigned int num = msg->payload.state.num;
> +
> +	debug("State.index: %u", index);
> +	debug("State.num:   %u", num);
> +	vdev->vq[index].vring.num = num;
> +
> +	return false;
> +}
> +
> +static bool vu_set_vring_addr_exec(VuDev *vdev,
> +				   struct VhostUserMsg *msg)
> +{
> +	struct vhost_vring_addr addr = msg->payload.addr, *vra = &addr;
> +	unsigned int index = vra->index;
> +	VuVirtq *vq = &vdev->vq[index];
> +
> +	debug("vhost_vring_addr:");
> +	debug("    index:  %d", vra->index);
> +	debug("    flags:  %d", vra->flags);
> +	debug("    desc_user_addr:   0x%016" PRIx64, (uint64_t)vra->desc_user_addr);
> +	debug("    used_user_addr:   0x%016" PRIx64, (uint64_t)vra->used_user_addr);
> +	debug("    avail_user_addr:  0x%016" PRIx64, (uint64_t)vra->avail_user_addr);
> +	debug("    log_guest_addr:   0x%016" PRIx64, (uint64_t)vra->log_guest_addr);
> +
> +	vq->vra = *vra;
> +	vq->vring.flags = vra->flags;
> +	vq->vring.log_guest_addr = vra->log_guest_addr;
> +
> +	if (map_ring(vdev, vq)) {
> +		vu_panic(vdev, "Invalid vring_addr message");
> +		return false;
> +	}
> +
> +	vq->used_idx = le16toh(vq->vring.used->idx);
> +
> +	if (vq->last_avail_idx != vq->used_idx) {
> +		debug("Last avail index != used index: %u != %u",
> +		      vq->last_avail_idx, vq->used_idx);
> +	}
> +
> +	return false;
> +}
> +
> +static bool vu_set_vring_base_exec(VuDev *vdev,
> +				   struct VhostUserMsg *msg)
> +{
> +	unsigned int index = msg->payload.state.index;
> +	unsigned int num = msg->payload.state.num;
> +
> +	debug("State.index: %u", index);
> +	debug("State.num:   %u", num);
> +	vdev->vq[index].shadow_avail_idx = vdev->vq[index].last_avail_idx = num;
> +
> +	return false;
> +}
> +
> +static bool vu_get_vring_base_exec(VuDev *vdev,
> +				   struct VhostUserMsg *msg)
> +{
> +	unsigned int index = msg->payload.state.index;
> +
> +	debug("State.index: %u", index);
> +	msg->payload.state.num = vdev->vq[index].last_avail_idx;
> +	msg->hdr.size = sizeof(msg->payload.state);
> +
> +	vdev->vq[index].started = false;
> +
> +	if (vdev->vq[index].call_fd != -1) {
> +		close(vdev->vq[index].call_fd);
> +		vdev->vq[index].call_fd = -1;
> +	}
> +	if (vdev->vq[index].kick_fd != -1) {
> +		vu_remove_watch(vdev,  vdev->vq[index].kick_fd);
> +		close(vdev->vq[index].kick_fd);
> +		vdev->vq[index].kick_fd = -1;
> +	}
> +
> +	return true;
> +}
> +
> +static void vu_set_watch(VuDev *vdev, int fd)
> +{
> +	struct ctx *c = (struct ctx *) ((char *)vdev - offsetof(struct ctx, vdev));
> +	union epoll_ref ref = { .type = EPOLL_TYPE_VHOST_KICK, .fd = fd };
> +	struct epoll_event ev = { 0 };
> +
> +	ev.data.u64 = ref.u64;
> +	ev.events = EPOLLIN;
> +	epoll_ctl(c->epollfd, EPOLL_CTL_ADD, fd, &ev);
> +}
> +
> +int vu_send(const struct ctx *c, const void *buf, size_t size)
> +{
> +	VuDev *vdev = (VuDev *)&c->vdev;
> +	size_t hdrlen = vdev->hdrlen;
> +	VuVirtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
> +	unsigned int indexes[VIRTQUEUE_MAX_SIZE];
> +	size_t lens[VIRTQUEUE_MAX_SIZE];
> +	size_t offset;
> +	int i, j;
> +	__virtio16 *num_buffers_ptr;
> +
> +	debug("vu_send size %zu hdrlen %zu", size, hdrlen);
> +
> +	if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) {
> +		err("Got packet, but no available descriptors on RX virtq.");

The message doesn't seem to quite match the condition.

> +		return 0;
> +	}
> +
> +	offset = 0;
> +	i = 0;
> +	num_buffers_ptr = NULL;
> +	while (offset < size) {
> +		VuVirtqElement *elem;
> +		size_t len;
> +		int total;
> +
> +		total = 0;
> +
> +		if (i == VIRTQUEUE_MAX_SIZE) {
> +			err("virtio-net unexpected long buffer chain");
> +			goto err;
> +		}
> +
> +		elem = vu_queue_pop(vdev, vq, sizeof(VuVirtqElement),
> +				    buffer[VHOST_USER_RX_QUEUE]);
> +		if (!elem) {
> +			if (!vdev->broken) {
> +				eventfd_t kick_data;
> +				ssize_t rc;
> +				int status;
> +
> +				/* wait the kernel to put new entries in the queue */
> +
> +				status = fcntl(vq->kick_fd, F_GETFL);
> +				if (status != -1) {
> +					fcntl(vq->kick_fd, F_SETFL, status & ~O_NONBLOCK);
> +					rc =  eventfd_read(vq->kick_fd, &kick_data);

Is it safe for us to block here?

> +					fcntl(vq->kick_fd, F_SETFL, status);
> +					if (rc != -1)
> +						continue;
> +				}
> +			}
> +			if (i) {
> +				err("virtio-net unexpected empty queue: "
> +				    "i %d mergeable %d offset %zd, size %zd, "
> +				    "features 0x%" PRIx64,
> +				    i, vu_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF),
> +				    offset, size, vdev->features);
> +			}
> +			offset = -1;
> +			goto err;
> +		}
> +
> +		if (elem->in_num < 1) {
> +			err("virtio-net receive queue contains no in buffers");
> +			vu_queue_detach_element(vdev, vq, elem->index, 0);
> +			offset = -1;
> +			goto err;
> +		}
> +
> +		if (i == 0) {
> +			struct virtio_net_hdr hdr = {
> +				.flags = VIRTIO_NET_HDR_F_DATA_VALID,
> +				.gso_type = VIRTIO_NET_HDR_GSO_NONE,
> +			};
> +
> +			ASSERT(offset == 0);
> +			ASSERT(elem->in_sg[0].iov_len >= hdrlen);
> +
> +			len = iov_from_buf(elem->in_sg, elem->in_num, 0, &hdr, sizeof hdr);
> +
> +			num_buffers_ptr = (__virtio16 *)((char *)elem->in_sg[0].iov_base +
> +							 len);
> +
> +			total += hdrlen;
> +		}
> +
> +		len = iov_from_buf(elem->in_sg, elem->in_num, total, (char *)buf + offset,
> +				   size - offset);
> +
> +		total += len;
> +		offset += len;
> +
> +		/* If buffers can't be merged, at this point we
> +		 * must have consumed the complete packet.
> +		 * Otherwise, drop it.
> +		 */
> +		if (!vu_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF) && offset < size) {
> +			vu_queue_unpop(vdev, vq, elem->index, total);
> +			goto err;
> +		}
> +
> +		indexes[i] = elem->index;
> +		lens[i] = total;
> +		i++;
> +	}
> +
> +	if (num_buffers_ptr && vu_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF)) {
> +		*num_buffers_ptr = htole16(i);
> +	}
> +
> +	for (j = 0; j < i; j++) {
> +		debug("filling total %zd idx %d", lens[j], j);
> +		vu_queue_fill_by_index(vdev, vq, indexes[j], lens[j], j);
> +	}
> +
> +	vu_queue_flush(vdev, vq, i);
> +	vu_queue_notify(vdev, vq);
> +
> +	debug("sent %zu", offset);
> +
> +	return offset;
> +err:
> +	for (j = 0; j < i; j++) {
> +		vu_queue_detach_element(vdev, vq, indexes[j], lens[j]);
> +	}
> +
> +	return offset;
> +}
> +
> +size_t tap_send_frames_vu(const struct ctx *c, const struct iovec *iov, size_t n)
> +{
> +	size_t i;
> +	int ret;
> +
> +	debug("tap_send_frames_vu n %zd", n);
> +
> +	for (i = 0; i < n; i++) {
> +		ret = vu_send(c, iov[i].iov_base, iov[i].iov_len);
> +		if (ret < 0)
> +			break;
> +	}
> +	debug("count %zd", i);
> +	return i;
> +}
> +
> +static void vu_handle_tx(VuDev *vdev, int index)
> +{
> +	struct ctx *c = (struct ctx *) ((char *)vdev - offsetof(struct ctx, vdev));
> +	VuVirtq *vq = &vdev->vq[index];
> +	int hdrlen = vdev->hdrlen;
> +	struct timespec now;
> +	char *p;
> +	size_t n;
> +
> +	if (index % 2 != VHOST_USER_TX_QUEUE) {
> +		debug("index %d is not an TX queue", index);

When would this situation arise?  It seems like it ought to be
something stronger than a debug() - either a fatal error in the setup
or an ASSERT().

> +		return;
> +	}
> +
> +	clock_gettime(CLOCK_MONOTONIC, &now);

If I'm looking ahead at the next patches to see how this is called
correctly, I think you can avoid this gettime() call by passing a
'now' value down from the mail epoll loop (the other tap handlers
already take one).

> +	p = pkt_buf;
> +
> +	pool_flush_all();
> +
> +	while (1) {
> +		VuVirtqElement *elem;
> +		unsigned int out_num;
> +		struct iovec sg[VIRTQUEUE_MAX_SIZE], *out_sg;
> +
> +		ASSERT(index == VHOST_USER_TX_QUEUE);

Hrm.. and isn't this redundant with the check at the start of the function?

> +		elem = vu_queue_pop(vdev, vq, sizeof(VuVirtqElement), buffer[index]);
> +		if (!elem) {
> +			break;
> +		}
> +
> +		out_num = elem->out_num;
> +		out_sg = elem->out_sg;
> +		if (out_num < 1) {
> +			debug("virtio-net header not in first element");
> +			break;
> +		}
> +
> +		if (hdrlen) {
> +			unsigned sg_num;
> +
> +			sg_num = iov_copy(sg, ARRAY_SIZE(sg), out_sg, out_num,
> +					  hdrlen, -1);
> +			out_num = sg_num;
> +			out_sg = sg;
> +		}
> +
> +		n = iov_to_buf(out_sg, out_num, 0, p, TAP_BUF_FILL);
> +
> +		packet_add_all(c, n, p);
> +
> +		p += n;
> +
> +		vu_queue_push(vdev, vq, elem, 0);
> +		vu_queue_notify(vdev, vq);
> +	}
> +	tap_handler_all(c, &now);
> +}
> +
> +void vu_kick_cb(struct ctx *c, union epoll_ref ref)
> +{
> +	VuDev *vdev = &c->vdev;
> +	eventfd_t kick_data;
> +	ssize_t rc;
> +	int index;
> +
> +	for (index = 0; index < VHOST_USER_MAX_QUEUES; index++)
> +		if (c->vdev.vq[index].kick_fd == ref.fd)
> +			break;
> +
> +	if (index == VHOST_USER_MAX_QUEUES)
> +		return;
> +
> +	rc =  eventfd_read(ref.fd, &kick_data);
> +	if (rc == -1) {
> +		vu_panic(vdev, "kick eventfd_read(): %s", strerror(errno));
> +		vu_remove_watch(vdev, ref.fd);
> +	} else {
> +		debug("Got kick_data: %016"PRIx64" idx:%d",
> +		      kick_data, index);
> +		if (index % 2 == VHOST_USER_TX_QUEUE)

.. and here we seem to have a third check for the same thing.

> +			vu_handle_tx(vdev, index);
> +	}
> +}
> +
> +static bool vu_check_queue_msg_file(VuDev *vdev, struct VhostUserMsg *msg)
> +{
> +	int index = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
> +	bool nofd = msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK;
> +
> +	if (index >= VHOST_USER_MAX_QUEUES) {
> +		vmsg_close_fds(msg);
> +		vu_panic(vdev, "Invalid queue index: %u", index);
> +		return false;
> +	}
> +
> +	if (nofd) {
> +		vmsg_close_fds(msg);
> +		return true;
> +	}
> +
> +	if (msg->fd_num != 1) {
> +		vmsg_close_fds(msg);
> +		vu_panic(vdev, "Invalid fds in request: %d", msg->hdr.request);
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
> +static bool vu_set_vring_kick_exec(VuDev *vdev,
> +				   struct VhostUserMsg *msg)
> +{
> +	int index = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
> +	bool nofd = msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK;
> +
> +	debug("u64: 0x%016"PRIx64, msg->payload.u64);
> +
> +	if (!vu_check_queue_msg_file(vdev, msg))
> +		return false;
> +
> +	if (vdev->vq[index].kick_fd != -1) {
> +		vu_remove_watch(vdev, vdev->vq[index].kick_fd);
> +		close(vdev->vq[index].kick_fd);
> +		vdev->vq[index].kick_fd = -1;
> +	}
> +
> +	vdev->vq[index].kick_fd = nofd ? -1 : msg->fds[0];
> +	debug("Got kick_fd: %d for vq: %d", vdev->vq[index].kick_fd, index);
> +
> +	vdev->vq[index].started = true;
> +
> +	if (vdev->vq[index].kick_fd != -1 && index % 2 == VHOST_USER_TX_QUEUE) {
> +		vu_set_watch(vdev, vdev->vq[index].kick_fd);
> +		debug("Waiting for kicks on fd: %d for vq: %d",
> +		      vdev->vq[index].kick_fd, index);
> +	}
> +
> +	return false;
> +}
> +
> +static bool vu_set_vring_call_exec(VuDev *vdev,
> +				   struct VhostUserMsg *msg)
> +{
> +	int index = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
> +	bool nofd = msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK;
> +
> +	debug("u64: 0x%016"PRIx64, msg->payload.u64);
> +
> +	if (!vu_check_queue_msg_file(vdev, msg))
> +		return false;
> +
> +	if (vdev->vq[index].call_fd != -1) {
> +		close(vdev->vq[index].call_fd);
> +		vdev->vq[index].call_fd = -1;
> +	}
> +
> +	vdev->vq[index].call_fd = nofd ? -1 : msg->fds[0];
> +
> +	/* in case of I/O hang after reconnecting */
> +	if (vdev->vq[index].call_fd != -1) {
> +		eventfd_write(msg->fds[0], 1);
> +	}
> +
> +	debug("Got call_fd: %d for vq: %d", vdev->vq[index].call_fd, index);
> +
> +	return false;
> +}
> +
> +static bool vu_set_vring_err_exec(VuDev *vdev,
> +				  struct VhostUserMsg *msg)
> +{
> +	int index = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
> +	bool nofd = msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK;
> +
> +	debug("u64: 0x%016"PRIx64, msg->payload.u64);
> +
> +	if (!vu_check_queue_msg_file(vdev, msg))
> +		return false;
> +
> +	if (vdev->vq[index].err_fd != -1) {
> +		close(vdev->vq[index].err_fd);
> +		vdev->vq[index].err_fd = -1;
> +	}
> +
> +	vdev->vq[index].err_fd = nofd ? -1 : msg->fds[0];
> +
> +	return false;
> +}
> +
> +static bool vu_get_protocol_features_exec(struct VhostUserMsg *msg)
> +{
> +	uint64_t features = 1ULL << VHOST_USER_PROTOCOL_F_REPLY_ACK;
> +
> +	vmsg_set_reply_u64(msg, features);
> +
> +	return true;
> +}
> +
> +static bool vu_set_protocol_features_exec(VuDev *vdev, struct VhostUserMsg *msg)
> +{
> +	uint64_t features = msg->payload.u64;
> +
> +	debug("u64: 0x%016"PRIx64, features);
> +
> +	vdev->protocol_features = msg->payload.u64;
> +
> +	if (vu_has_protocol_feature(vdev,
> +				    VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS) &&
> +	    (!vu_has_protocol_feature(vdev, VHOST_USER_PROTOCOL_F_BACKEND_REQ) ||
> +	     !vu_has_protocol_feature(vdev, VHOST_USER_PROTOCOL_F_REPLY_ACK))) {
> +		/*
> +		 * The use case for using messages for kick/call is simulation, to make
> +		 * the kick and call synchronous. To actually get that behaviour, both
> +		 * of the other features are required.
> +		 * Theoretically, one could use only kick messages, or do them without
> +		 * having F_REPLY_ACK, but too many (possibly pending) messages on the
> +		 * socket will eventually cause the master to hang, to avoid this in
> +		 * scenarios where not desired enforce that the settings are in a way
> +		 * that actually enables the simulation case.
> +		 */
> +		vu_panic(vdev,
> +			 "F_IN_BAND_NOTIFICATIONS requires F_BACKEND_REQ && F_REPLY_ACK");
> +		return false;
> +	}
> +
> +	return false;
> +}
> +
> +
> +static bool vu_get_queue_num_exec(struct VhostUserMsg *msg)
> +{
> +	vmsg_set_reply_u64(msg, VHOST_USER_MAX_QUEUES);
> +	return true;
> +}
> +
> +static bool vu_set_vring_enable_exec(VuDev *vdev, struct VhostUserMsg *msg)
> +{
> +	unsigned int index = msg->payload.state.index;
> +	unsigned int enable = msg->payload.state.num;
> +
> +	debug("State.index:  %u", index);
> +	debug("State.enable: %u", enable);
> +
> +	if (index >= VHOST_USER_MAX_QUEUES) {
> +		vu_panic(vdev, "Invalid vring_enable index: %u", index);
> +		return false;
> +	}
> +
> +	vdev->vq[index].enable = enable;
> +	return false;
> +}
> +
> +void vu_init(struct ctx *c)
> +{
> +	int i;
> +
> +	c->vdev.hdrlen = 0;
> +	for (i = 0; i < VHOST_USER_MAX_QUEUES; i++)
> +		c->vdev.vq[i] = (VuVirtq){
> +			.call_fd = -1,
> +			.kick_fd = -1,
> +			.err_fd = -1,
> +			.notification = true,
> +		};
> +}
> +
> +static void vu_cleanup(VuDev *vdev)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < VHOST_USER_MAX_QUEUES; i++) {
> +		VuVirtq *vq = &vdev->vq[i];
> +
> +		vq->started = false;
> +		vq->notification = true;
> +
> +		if (vq->call_fd != -1) {
> +			close(vq->call_fd);
> +			vq->call_fd = -1;
> +		}
> +		if (vq->err_fd != -1) {
> +			close(vq->err_fd);
> +			vq->err_fd = -1;
> +		}
> +		if (vq->kick_fd != -1) {
> +			vu_remove_watch(vdev,  vq->kick_fd);
> +			close(vq->kick_fd);
> +			vq->kick_fd = -1;
> +		}
> +
> +		vq->vring.desc = 0;
> +		vq->vring.used = 0;
> +		vq->vring.avail = 0;
> +	}
> +	vdev->hdrlen = 0;
> +
> +	for (i = 0; i < vdev->nregions; i++) {
> +		VuDevRegion *r = &vdev->regions[i];
> +		void *m = (void *) (uintptr_t) r->mmap_addr;
> +
> +		if (m)
> +			munmap(m, r->size + r->mmap_offset);
> +	}
> +	vdev->nregions = 0;
> +}
> +
> +/**
> + * tap_handler_vu() - Packet handler for vhost-user
> + * @c:		Execution context
> + * @events:	epoll events
> + */
> +void tap_handler_vu(struct ctx *c, uint32_t events)
> +{
> +	VuDev *dev = &c->vdev;
> +	struct VhostUserMsg msg = { 0 };
> +	bool need_reply, reply_requested;
> +	int ret;
> +
> +	if (events & (EPOLLRDHUP | EPOLLHUP | EPOLLERR)) {
> +		tap_sock_reset(c);
> +		return;
> +	}
> +
> +
> +	ret = vu_message_read_default(dev, c->fd_tap, &msg);
> +	if (ret <= 0) {
> +		if (errno != EINTR && errno != EAGAIN && errno != EWOULDBLOCK)
> +			tap_sock_reset(c);
> +		return;
> +	}
> +	debug("================ Vhost user message ================");
> +	debug("Request: %s (%d)", vu_request_to_string(msg.hdr.request),
> +		msg.hdr.request);
> +	debug("Flags:   0x%x", msg.hdr.flags);
> +	debug("Size:    %u", msg.hdr.size);
> +
> +	need_reply = msg.hdr.flags & VHOST_USER_NEED_REPLY_MASK;
> +	switch (msg.hdr.request) {
> +	case VHOST_USER_GET_FEATURES:
> +		reply_requested = vu_get_features_exec(&msg);
> +		break;
> +	case VHOST_USER_SET_FEATURES:
> +		reply_requested = vu_set_features_exec(dev, &msg);
> +		break;
> +	case VHOST_USER_GET_PROTOCOL_FEATURES:
> +		reply_requested = vu_get_protocol_features_exec(&msg);
> +		break;
> +	case VHOST_USER_SET_PROTOCOL_FEATURES:
> +		reply_requested = vu_set_protocol_features_exec(dev, &msg);
> +		break;
> +	case VHOST_USER_GET_QUEUE_NUM:
> +		reply_requested = vu_get_queue_num_exec(&msg);
> +		break;
> +	case VHOST_USER_SET_OWNER:
> +		reply_requested = vu_set_owner_exec();
> +		break;
> +	case VHOST_USER_SET_MEM_TABLE:
> +		reply_requested = vu_set_mem_table_exec(dev, &msg);
> +		break;
> +	case VHOST_USER_SET_VRING_NUM:
> +		reply_requested = vu_set_vring_num_exec(dev, &msg);
> +		break;
> +	case VHOST_USER_SET_VRING_ADDR:
> +		reply_requested = vu_set_vring_addr_exec(dev, &msg);
> +		break;
> +	case VHOST_USER_SET_VRING_BASE:
> +		reply_requested = vu_set_vring_base_exec(dev, &msg);
> +		break;
> +	case VHOST_USER_GET_VRING_BASE:
> +		reply_requested = vu_get_vring_base_exec(dev, &msg);
> +		break;
> +	case VHOST_USER_SET_VRING_KICK:
> +		reply_requested = vu_set_vring_kick_exec(dev, &msg);
> +		break;
> +	case VHOST_USER_SET_VRING_CALL:
> +		reply_requested = vu_set_vring_call_exec(dev, &msg);
> +		break;
> +	case VHOST_USER_SET_VRING_ERR:
> +		reply_requested = vu_set_vring_err_exec(dev, &msg);
> +		break;
> +	case VHOST_USER_SET_VRING_ENABLE:
> +		reply_requested = vu_set_vring_enable_exec(dev, &msg);
> +		break;
> +	case VHOST_USER_NONE:
> +		vu_cleanup(dev);
> +		return;
> +	default:
> +		vu_panic(dev, "Unhandled request: %d", msg.hdr.request);
> +		return;
> +	}
> +
> +	if (!reply_requested && need_reply) {
> +		msg.payload.u64 = 0;
> +		msg.hdr.flags = 0;
> +		msg.hdr.size = sizeof(msg.payload.u64);
> +		msg.fd_num = 0;
> +		reply_requested = true;
> +	}
> +
> +	if (reply_requested)
> +		ret = vu_send_reply(dev, c->fd_tap, &msg);
> +	free(msg.data);
> +}
> diff --git a/vhost_user.h b/vhost_user.h
> new file mode 100644
> index 000000000000..25f0b617ab40
> --- /dev/null
> +++ b/vhost_user.h
> @@ -0,0 +1,139 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +
> +/* some parts from subprojects/libvhost-user/libvhost-user.h */
> +
> +#ifndef VHOST_USER_H
> +#define VHOST_USER_H
> +
> +#include "virtio.h"
> +#include "iov.h"
> +
> +#define VHOST_USER_F_PROTOCOL_FEATURES 30
> +
> +#define VHOST_MEMORY_BASELINE_NREGIONS 8
> +
> +enum vhost_user_protocol_feature {
> +	VHOST_USER_PROTOCOL_F_MQ = 0,
> +	VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
> +	VHOST_USER_PROTOCOL_F_RARP = 2,
> +	VHOST_USER_PROTOCOL_F_REPLY_ACK = 3,
> +	VHOST_USER_PROTOCOL_F_NET_MTU = 4,
> +	VHOST_USER_PROTOCOL_F_BACKEND_REQ = 5,
> +	VHOST_USER_PROTOCOL_F_CROSS_ENDIAN = 6,
> +	VHOST_USER_PROTOCOL_F_CRYPTO_SESSION = 7,
> +	VHOST_USER_PROTOCOL_F_PAGEFAULT = 8,
> +	VHOST_USER_PROTOCOL_F_CONFIG = 9,
> +	VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD = 10,
> +	VHOST_USER_PROTOCOL_F_HOST_NOTIFIER = 11,
> +	VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD = 12,
> +	VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS = 14,
> +	VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS = 15,
> +
> +	VHOST_USER_PROTOCOL_F_MAX
> +};
> +
> +enum vhost_user_request {
> +	VHOST_USER_NONE = 0,
> +	VHOST_USER_GET_FEATURES = 1,
> +	VHOST_USER_SET_FEATURES = 2,
> +	VHOST_USER_SET_OWNER = 3,
> +	VHOST_USER_RESET_OWNER = 4,
> +	VHOST_USER_SET_MEM_TABLE = 5,
> +	VHOST_USER_SET_LOG_BASE = 6,
> +	VHOST_USER_SET_LOG_FD = 7,
> +	VHOST_USER_SET_VRING_NUM = 8,
> +	VHOST_USER_SET_VRING_ADDR = 9,
> +	VHOST_USER_SET_VRING_BASE = 10,
> +	VHOST_USER_GET_VRING_BASE = 11,
> +	VHOST_USER_SET_VRING_KICK = 12,
> +	VHOST_USER_SET_VRING_CALL = 13,
> +	VHOST_USER_SET_VRING_ERR = 14,
> +	VHOST_USER_GET_PROTOCOL_FEATURES = 15,
> +	VHOST_USER_SET_PROTOCOL_FEATURES = 16,
> +	VHOST_USER_GET_QUEUE_NUM = 17,
> +	VHOST_USER_SET_VRING_ENABLE = 18,
> +	VHOST_USER_SEND_RARP = 19,
> +	VHOST_USER_NET_SET_MTU = 20,
> +	VHOST_USER_SET_BACKEND_REQ_FD = 21,
> +	VHOST_USER_IOTLB_MSG = 22,
> +	VHOST_USER_SET_VRING_ENDIAN = 23,
> +	VHOST_USER_GET_CONFIG = 24,
> +	VHOST_USER_SET_CONFIG = 25,
> +	VHOST_USER_CREATE_CRYPTO_SESSION = 26,
> +	VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
> +	VHOST_USER_POSTCOPY_ADVISE  = 28,
> +	VHOST_USER_POSTCOPY_LISTEN  = 29,
> +	VHOST_USER_POSTCOPY_END     = 30,
> +	VHOST_USER_GET_INFLIGHT_FD = 31,
> +	VHOST_USER_SET_INFLIGHT_FD = 32,
> +	VHOST_USER_GPU_SET_SOCKET = 33,
> +	VHOST_USER_VRING_KICK = 35,
> +	VHOST_USER_GET_MAX_MEM_SLOTS = 36,
> +	VHOST_USER_ADD_MEM_REG = 37,
> +	VHOST_USER_REM_MEM_REG = 38,
> +	VHOST_USER_MAX
> +};
> +
> +typedef struct {
> +	enum vhost_user_request request;
> +
> +#define VHOST_USER_VERSION_MASK     0x3
> +#define VHOST_USER_REPLY_MASK       (0x1 << 2)
> +#define VHOST_USER_NEED_REPLY_MASK  (0x1 << 3)
> +	uint32_t flags;
> +	uint32_t size; /* the following payload size */
> +} __attribute__ ((__packed__)) vhost_user_header;
> +
> +typedef struct VhostUserMemory_region {
> +	uint64_t guest_phys_addr;
> +	uint64_t memory_size;
> +	uint64_t userspace_addr;
> +	uint64_t mmap_offset;
> +} VhostUserMemory_region;
> +
> +struct VhostUserMemory {
> +	uint32_t nregions;
> +	uint32_t padding;
> +	struct VhostUserMemory_region regions[VHOST_MEMORY_BASELINE_NREGIONS];
> +};
> +
> +typedef union {
> +#define VHOST_USER_VRING_IDX_MASK   0xff
> +#define VHOST_USER_VRING_NOFD_MASK  (0x1 << 8)
> +	uint64_t u64;
> +	struct vhost_vring_state state;
> +	struct vhost_vring_addr addr;
> +	struct VhostUserMemory memory;
> +} vhost_user_payload;
> +
> +typedef struct VhostUserMsg {
> +	vhost_user_header hdr;
> +	vhost_user_payload payload;
> +
> +	int fds[VHOST_MEMORY_BASELINE_NREGIONS];
> +	int fd_num;
> +	uint8_t *data;
> +} __attribute__ ((__packed__)) VhostUserMsg;
> +#define VHOST_USER_HDR_SIZE sizeof(vhost_user_header)
> +
> +#define VHOST_USER_RX_QUEUE 0
> +#define VHOST_USER_TX_QUEUE 1
> +
> +static inline bool vu_queue_enabled(VuVirtq *vq)
> +{
> +	return vq->enable;
> +}
> +
> +static inline bool vu_queue_started(const VuVirtq *vq)
> +{
> +	return vq->started;
> +}
> +
> +size_t tap_send_frames_vu(const struct ctx *c, const struct iovec *iov,
> +			  size_t n);
> +int vu_send(const struct ctx *c, const void *data, size_t len);
> +void vu_print_capabilities(void);
> +void vu_init(struct ctx *c);
> +void vu_kick_cb(struct ctx *c, union epoll_ref ref);
> +void tap_handler_vu(struct ctx *c, uint32_t events);
> +#endif /* VHOST_USER_H */

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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