Re: [dpdk-dev] [PATCH v7 04/10] vhost: add two new messages to support a shared buffer

[Tiwei Bie <tiwei.bie@intel.com>]

On Fri, Sep 20, 2019 at 08:00:56PM +0800, Jin Yu wrote:
> This patch introduces two new messages VHOST_USER_GET_INFLIGHT_FD
> and VHOST_USER_SET_INFLIGHT_FD to support transferring a shared
> buffer between qemu and backend.
> 
> Signed-off-by: Lin Li <lilin24@baidu.com>
> Signed-off-by: Xun Ni <nixun@baidu.com>
> Signed-off-by: Yu Zhang <zhangyu31@baidu.com>
> Signed-off-by: Jin Yu <jin.yu@intel.com>
> ---
>  lib/librte_vhost/vhost.h      |   7 +
>  lib/librte_vhost/vhost_user.c | 260 +++++++++++++++++++++++++++++++++-
>  lib/librte_vhost/vhost_user.h |   4 +-
>  3 files changed, 269 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 884befa85..d67ba849a 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -286,6 +286,12 @@ struct guest_page {
>  	uint64_t size;
>  };
>  
> +struct inflight_mem_info {
> +	int		fd;
> +	void		*addr;
> +	uint64_t	size;
> +};
> +
>  /**
>   * Device structure contains all configuration information relating
>   * to the device.
> @@ -303,6 +309,7 @@ struct virtio_net {
>  	uint32_t		nr_vring;
>  	int			dequeue_zero_copy;
>  	struct vhost_virtqueue	*virtqueue[VHOST_MAX_QUEUE_PAIRS * 2];
> +	struct inflight_mem_info *inflight_info;
>  #define IF_NAME_SZ (PATH_MAX > IFNAMSIZ ? PATH_MAX : IFNAMSIZ)
>  	char			ifname[IF_NAME_SZ];
>  	uint64_t		log_size;
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index c9e29ece8..66582a30f 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -37,6 +37,10 @@
>  #ifdef RTE_LIBRTE_VHOST_POSTCOPY
>  #include <linux/userfaultfd.h>
>  #endif
> +#ifdef F_ADD_SEALS /* if file sealing is supported, so is memfd */
> +#include <linux/memfd.h>
> +#define MEMFD_SUPPORTED
> +#endif
>  
>  #include <rte_common.h>
>  #include <rte_malloc.h>
> @@ -49,6 +53,15 @@
>  #define VIRTIO_MIN_MTU 68
>  #define VIRTIO_MAX_MTU 65535
>  
> +#define INFLIGHT_ALIGNMENT	64
> +#define INFLIGHT_VERSION	0xabcd

Why the version is 0xabcd? Shouldn't it be 1?

https://git.qemu.org/?p=qemu.git;a=blob;f=docs/interop/vhost-user.rst;h=7827b710aa0a223f6f184b229f4b5ced6420b638;hb=HEAD#l551
https://git.qemu.org/?p=qemu.git;a=blob;f=docs/interop/vhost-user.rst;h=7827b710aa0a223f6f184b229f4b5ced6420b638;hb=HEAD#l658

> +#define VIRTQUEUE_MAX_SIZE	1024
> +
> +#define CLOEXEC		0x0001U
> +
> +#define ALIGN_DOWN(n, m) ((n) / (m) * (m))
> +#define ALIGN_UP(n, m) ALIGN_DOWN((n) + (m) - 1, (m))
> +
>  static const char *vhost_message_str[VHOST_USER_MAX] = {
>  	[VHOST_USER_NONE] = "VHOST_USER_NONE",
>  	[VHOST_USER_GET_FEATURES] = "VHOST_USER_GET_FEATURES",
> @@ -78,6 +91,8 @@ static const char *vhost_message_str[VHOST_USER_MAX] = {
>  	[VHOST_USER_POSTCOPY_ADVISE]  = "VHOST_USER_POSTCOPY_ADVISE",
>  	[VHOST_USER_POSTCOPY_LISTEN]  = "VHOST_USER_POSTCOPY_LISTEN",
>  	[VHOST_USER_POSTCOPY_END]  = "VHOST_USER_POSTCOPY_END",
> +	[VHOST_USER_GET_INFLIGHT_FD] = "VHOST_USER_GET_INFLIGHT_FD",
> +	[VHOST_USER_SET_INFLIGHT_FD] = "VHOST_USER_SET_INFLIGHT_FD",
>  };
>  
>  static int send_vhost_reply(int sockfd, struct VhostUserMsg *msg);
> @@ -160,6 +175,21 @@ vhost_backend_cleanup(struct virtio_net *dev)
>  		dev->log_addr = 0;
>  	}
>  
> +	if (dev->inflight_info->addr) {
> +		munmap(dev->inflight_info->addr, dev->inflight_info->size);
> +		dev->inflight_info->addr = NULL;
> +	}
> +
> +	if (dev->inflight_info->fd > 0) {
> +		close(dev->inflight_info->fd);
> +		dev->inflight_info->fd = -1;
> +	}
> +
> +	if (dev->inflight_info) {
> +		free(dev->inflight_info);
> +		dev->inflight_info = NULL;
> +	}

You should check dev->inflight_info first before dereferencing it.

> +
>  	if (dev->slave_req_fd >= 0) {
>  		close(dev->slave_req_fd);
>  		dev->slave_req_fd = -1;
> @@ -1165,6 +1195,233 @@ virtio_is_ready(struct virtio_net *dev)
>  	return 1;
>  }
>  
> +static int
> +mem_create(const char *name, unsigned int flags)
> +{
> +#ifdef MEMFD_SUPPORTED
> +	return memfd_create(name, flags);
> +#else
> +	RTE_LOG(ERR, VHOST_CONFIG,
> +		"doesn't support memfd--name:%s and flag:%x\n",
> +		name, flags);

You probably don't want to always print an error when
memfd isn't available.

> +	return -1;
> +#endif
> +}
> +
> +static void *
> +inflight_mem_alloc(const char *name, size_t size, int *fd)
> +{
> +	void *ptr;
> +	int mfd = -1;
> +	char fname[20] = "/tmp/memfd-XXXXXX";
> +
> +	*fd = -1;
> +	mfd = mem_create(name, CLOEXEC);
> +	if (mfd != -1) {
> +		if (ftruncate(mfd, size) == -1) {
> +			RTE_LOG(ERR, VHOST_CONFIG,
> +				"ftruncate fail for alloc inflight buffer\n");
> +			close(mfd);
> +			return NULL;
> +		}
> +	} else {
> +		mfd = mkstemp(fname);
> +		unlink(fname);
> +
> +		if (mfd == -1) {
> +			RTE_LOG(ERR, VHOST_CONFIG,
> +				"mkstemp fail for alloc inflight buffer\n");
> +			return NULL;
> +		}
> +
> +		if (ftruncate(mfd, size) == -1) {
> +			RTE_LOG(ERR, VHOST_CONFIG,
> +				"ftruncate fail for alloc inflight buffer\n");
> +			close(mfd);
> +			return NULL;
> +		}
> +	}
> +
> +	ptr = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, mfd, 0);
> +	if (ptr == MAP_FAILED) {
> +		RTE_LOG(ERR, VHOST_CONFIG,
> +			"mmap fail for alloc inflight buffer\n");
> +		close(mfd);
> +		return NULL;
> +	}
> +
> +	*fd = mfd;
> +	return ptr;
> +}
> +
> +static uint32_t
> +get_pervq_shm_size_split(uint16_t queue_size)
> +{
> +	return ALIGN_UP(sizeof(struct rte_vhost_inflight_desc_split) *
> +			queue_size + sizeof(uint64_t) + sizeof(uint16_t) * 4,
> +			INFLIGHT_ALIGNMENT);
> +}
> +
> +static uint32_t
> +get_pervq_shm_size_packed(uint16_t queue_size)
> +{
> +	return ALIGN_UP(sizeof(struct rte_vhost_inflight_desc_packed) *
> +			queue_size + sizeof(uint64_t) + sizeof(uint16_t) * 6 +
> +			sizeof(uint8_t) * 9, INFLIGHT_ALIGNMENT);
> +}
> +
> +static int
> +vhost_user_get_inflight_fd(struct virtio_net **pdev,
> +				     VhostUserMsg *msg,
> +				     int main_fd __rte_unused)
> +{
> +	int fd, i, j;
> +	uint64_t pervq_inflight_size, mmap_size;
> +	void *addr;
> +	uint16_t num_queues, queue_size;
> +	struct virtio_net *dev = *pdev;
> +	struct rte_vhost_inflight_info_packed *inflight_packed = NULL;
> +
> +	if (msg->size != sizeof(msg->payload.inflight)) {
> +		RTE_LOG(ERR, VHOST_CONFIG,
> +			"Invalid get_inflight_fd message size is %d",
> +			msg->size);
> +		return RTE_VHOST_MSG_RESULT_ERR;
> +	}
> +
> +	dev->inflight_info = calloc(1, sizeof(struct inflight_mem_info));

You need to check whether dev->inflight_info has been allocated,
otherwise memory may leak.

> +	if (!dev->inflight_info) {
> +		RTE_LOG(ERR, VHOST_CONFIG,
> +			"Failed to alloc dev inflight area");
> +		return RTE_VHOST_MSG_RESULT_ERR;
> +	}
> +
> +	num_queues = msg->payload.inflight.num_queues;
> +	queue_size = msg->payload.inflight.queue_size;
> +
> +	RTE_LOG(INFO, VHOST_CONFIG, "get_inflight_fd num_queues: %u\n",
> +		msg->payload.inflight.num_queues);
> +	RTE_LOG(INFO, VHOST_CONFIG, "get_inflight_fd queue_size: %u\n",
> +		msg->payload.inflight.queue_size);
> +
> +	if (vq_is_packed(dev))
> +		pervq_inflight_size = get_pervq_shm_size_packed(queue_size);
> +	else
> +		pervq_inflight_size = get_pervq_shm_size_split(queue_size);
> +
> +	mmap_size = num_queues * pervq_inflight_size;
> +	addr = inflight_mem_alloc("vhost-inflight", mmap_size, &fd);
> +	if (!addr) {
> +		RTE_LOG(ERR, VHOST_CONFIG,
> +			"Failed to alloc vhost inflight area");
> +			msg->payload.inflight.mmap_size = 0;
> +		return RTE_VHOST_MSG_RESULT_ERR;
> +	}
> +	memset(addr, 0, mmap_size);
> +
> +	dev->inflight_info->addr = addr;
> +	dev->inflight_info->size = msg->payload.inflight.mmap_size = mmap_size;
> +	dev->inflight_info->fd = msg->fds[0] = fd;
> +	msg->payload.inflight.mmap_offset = 0;
> +	msg->fd_num = 1;
> +
> +	if (vq_is_packed(dev)) {
> +		for (i = 0; i < num_queues; i++) {
> +			inflight_packed =
> +				(struct rte_vhost_inflight_info_packed *)addr;
> +			inflight_packed->used_wrap_counter = 1;
> +			inflight_packed->old_used_wrap_counter = 1;
> +			for (j = 0; j < queue_size; j++)
> +				inflight_packed->desc[j].next = j + 1;
> +			addr = (void *)((char *)addr + pervq_inflight_size);
> +		}
> +	}
> +
> +	RTE_LOG(INFO, VHOST_CONFIG,
> +		"send inflight mmap_size: %"PRIu64"\n",
> +		msg->payload.inflight.mmap_size);
> +	RTE_LOG(INFO, VHOST_CONFIG,
> +		"send inflight mmap_offset: %"PRIu64"\n",
> +		msg->payload.inflight.mmap_offset);
> +	RTE_LOG(INFO, VHOST_CONFIG,
> +		"send inflight fd: %d\n", msg->fds[0]);
> +
> +	return RTE_VHOST_MSG_RESULT_REPLY;
> +}
> +
> +static int
> +vhost_user_set_inflight_fd(struct virtio_net **pdev, VhostUserMsg *msg,
> +		int main_fd __rte_unused)
> +{
> +	int fd;
> +	uint64_t mmap_size, mmap_offset;
> +	uint16_t num_queues, queue_size;
> +	uint32_t pervq_inflight_size;
> +	void *addr;
> +	struct virtio_net *dev = *pdev;
> +
> +	fd = msg->fds[0];
> +	if (msg->size != sizeof(msg->payload.inflight) || fd < 0) {
> +		RTE_LOG(ERR, VHOST_CONFIG,
> +			"Invalid set_inflight_fd message size is %d,fd is %d\n",
> +			msg->size, fd);
> +		return RTE_VHOST_MSG_RESULT_ERR;
> +	}
> +
> +	mmap_size = msg->payload.inflight.mmap_size;
> +	mmap_offset = msg->payload.inflight.mmap_offset;
> +	num_queues = msg->payload.inflight.num_queues;
> +	queue_size = msg->payload.inflight.queue_size;
> +
> +	if (vq_is_packed(dev))
> +		pervq_inflight_size = get_pervq_shm_size_packed(queue_size);
> +	else
> +		pervq_inflight_size = get_pervq_shm_size_split(queue_size);
> +
> +	RTE_LOG(INFO, VHOST_CONFIG,
> +		"set_inflight_fd mmap_size: %"PRIu64"\n", mmap_size);
> +	RTE_LOG(INFO, VHOST_CONFIG,
> +		"set_inflight_fd mmap_offset: %"PRIu64"\n", mmap_offset);
> +	RTE_LOG(INFO, VHOST_CONFIG,
> +		"set_inflight_fd num_queues: %u\n", num_queues);
> +	RTE_LOG(INFO, VHOST_CONFIG,
> +		"set_inflight_fd queue_size: %u\n", queue_size);
> +	RTE_LOG(INFO, VHOST_CONFIG,
> +		"set_inflight_fd fd: %d\n", fd);
> +	RTE_LOG(INFO, VHOST_CONFIG,
> +		"set_inflight_fd pervq_inflight_size: %d\n",
> +		pervq_inflight_size);
> +
> +	if (!dev->inflight_info) {
> +		dev->inflight_info = calloc(1,
> +					    sizeof(struct inflight_mem_info));
> +		if (dev->inflight_info == NULL) {
> +			RTE_LOG(ERR, VHOST_CONFIG,
> +				"Failed to alloc dev inflight area");
> +			return RTE_VHOST_MSG_RESULT_ERR;
> +		}
> +	}
> +
> +	if (dev->inflight_info->addr)
> +		munmap(dev->inflight_info->addr, dev->inflight_info->size);

dev->inflight_info->addr won't be zeroed when below mmap() fails.

> +
> +	addr = mmap(0, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED,
> +			fd, mmap_offset);
> +	if (addr == MAP_FAILED) {
> +		RTE_LOG(ERR, VHOST_CONFIG, "failed to mmap share memory.\n");
> +		return RTE_VHOST_MSG_RESULT_ERR;
> +	}
> +
> +	if (dev->inflight_info->fd)
> +		close(dev->inflight_info->fd);
> +
> +	dev->inflight_info->fd = fd;
> +	dev->inflight_info->addr = addr;
> +	dev->inflight_info->size = mmap_size;
> +
> +	return RTE_VHOST_MSG_RESULT_OK;
> +}
> +
>  static int
>  vhost_user_set_vring_call(struct virtio_net **pdev, struct VhostUserMsg *msg,
>  			int main_fd __rte_unused)
> @@ -1762,9 +2019,10 @@ static vhost_message_handler_t vhost_message_handlers[VHOST_USER_MAX] = {
>  	[VHOST_USER_POSTCOPY_ADVISE] = vhost_user_set_postcopy_advise,
>  	[VHOST_USER_POSTCOPY_LISTEN] = vhost_user_set_postcopy_listen,
>  	[VHOST_USER_POSTCOPY_END] = vhost_user_postcopy_end,
> +	[VHOST_USER_GET_INFLIGHT_FD] = vhost_user_get_inflight_fd,
> +	[VHOST_USER_SET_INFLIGHT_FD] = vhost_user_set_inflight_fd,
>  };
>  
> -
>  /* return bytes# of read on success or negative val on failure. */
>  static int
>  read_vhost_message(int sockfd, struct VhostUserMsg *msg)
> diff --git a/lib/librte_vhost/vhost_user.h b/lib/librte_vhost/vhost_user.h
> index 17a1d7bca..6563f7315 100644
> --- a/lib/librte_vhost/vhost_user.h
> +++ b/lib/librte_vhost/vhost_user.h
> @@ -54,7 +54,9 @@ typedef enum VhostUserRequest {
>  	VHOST_USER_POSTCOPY_ADVISE = 28,
>  	VHOST_USER_POSTCOPY_LISTEN = 29,
>  	VHOST_USER_POSTCOPY_END = 30,
> -	VHOST_USER_MAX = 31
> +	VHOST_USER_GET_INFLIGHT_FD = 31,
> +	VHOST_USER_SET_INFLIGHT_FD = 32,
> +	VHOST_USER_MAX = 33
>  } VhostUserRequest;
>  
>  typedef enum VhostUserSlaveRequest {
> -- 
> 2.17.2
>