Re: [dpdk-dev] [PATCH v2 1/6] vhost: handle VHOST_USER_SET_LOG_BASE request

["Xie, Huawei" <huawei.xie@intel.com>]

On 12/17/2015 11:11 AM, Yuanhan Liu wrote:
> VHOST_USER_SET_LOG_BASE request is used to tell the backend (dpdk
> vhost-user) where we should log dirty pages, and how big the log
> buffer is.
>
> This request introduces a new payload:
>
>     typedef struct VhostUserLog {
>             uint64_t mmap_size;
>             uint64_t mmap_offset;
>     } VhostUserLog;
>
> Also, a fd is delivered from QEMU by ancillary data.
>
> With those info given, an area of memory is mmaped, assigned
> to dev->log_base, for logging dirty pages.
>
> Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
> Signed-off-by: Victor Kaplansky <victork@redhat.com
> ---
>
> v2: workaround mmap issue when offset is not zero
> ---
>  lib/librte_vhost/rte_virtio_net.h             |  4 ++-
>  lib/librte_vhost/vhost_user/vhost-net-user.c  |  7 ++--
>  lib/librte_vhost/vhost_user/vhost-net-user.h  |  6 ++++
>  lib/librte_vhost/vhost_user/virtio-net-user.c | 48 +++++++++++++++++++++++++++
>  lib/librte_vhost/vhost_user/virtio-net-user.h |  1 +
>  5 files changed, 63 insertions(+), 3 deletions(-)
>
> diff --git a/lib/librte_vhost/rte_virtio_net.h b/lib/librte_vhost/rte_virtio_net.h
> index 10dcb90..8acee02 100644
> --- a/lib/librte_vhost/rte_virtio_net.h
> +++ b/lib/librte_vhost/rte_virtio_net.h
> @@ -129,7 +129,9 @@ struct virtio_net {
>  	char			ifname[IF_NAME_SZ];	/**< Name of the tap device or socket path. */
>  	uint32_t		virt_qp_nb;	/**< number of queue pair we have allocated */
>  	void			*priv;		/**< private context */
> -	uint64_t		reserved[64];	/**< Reserve some spaces for future extension. */
> +	uint64_t		log_size;	/**< Size of log area */
> +	uint64_t		log_base;	/**< Where dirty pages are logged */
> +	uint64_t		reserved[62];	/**< Reserve some spaces for future extension. */
>  	struct vhost_virtqueue	*virtqueue[VHOST_MAX_QUEUE_PAIRS * 2];	/**< Contains all virtqueue information. */
>  } __rte_cache_aligned;
>  
> diff --git a/lib/librte_vhost/vhost_user/vhost-net-user.c b/lib/librte_vhost/vhost_user/vhost-net-user.c
> index 8b7a448..32ad6f6 100644
> --- a/lib/librte_vhost/vhost_user/vhost-net-user.c
> +++ b/lib/librte_vhost/vhost_user/vhost-net-user.c
> @@ -388,9 +388,12 @@ vserver_message_handler(int connfd, void *dat, int *remove)
>  		break;
>  
>  	case VHOST_USER_SET_LOG_BASE:
> -		RTE_LOG(INFO, VHOST_CONFIG, "not implemented.\n");
> -		break;
> +		user_set_log_base(ctx, &msg);
>  
> +		/* it needs a reply */
> +		msg.size = sizeof(msg.payload.u64);
> +		send_vhost_message(connfd, &msg);
> +		break;
>  	case VHOST_USER_SET_LOG_FD:
>  		close(msg.fds[0]);
>  		RTE_LOG(INFO, VHOST_CONFIG, "not implemented.\n");
> diff --git a/lib/librte_vhost/vhost_user/vhost-net-user.h b/lib/librte_vhost/vhost_user/vhost-net-user.h
> index 38637cc..6d252a3 100644
> --- a/lib/librte_vhost/vhost_user/vhost-net-user.h
> +++ b/lib/librte_vhost/vhost_user/vhost-net-user.h
> @@ -83,6 +83,11 @@ typedef struct VhostUserMemory {
>  	VhostUserMemoryRegion regions[VHOST_MEMORY_MAX_NREGIONS];
>  } VhostUserMemory;
>  
> +typedef struct VhostUserLog {
> +	uint64_t mmap_size;
> +	uint64_t mmap_offset;
> +} VhostUserLog;
> +
>  typedef struct VhostUserMsg {
>  	VhostUserRequest request;
>  
> @@ -97,6 +102,7 @@ typedef struct VhostUserMsg {
>  		struct vhost_vring_state state;
>  		struct vhost_vring_addr addr;
>  		VhostUserMemory memory;
> +		VhostUserLog    log;
>  	} payload;
>  	int fds[VHOST_MEMORY_MAX_NREGIONS];
>  } __attribute((packed)) VhostUserMsg;
> diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.c b/lib/librte_vhost/vhost_user/virtio-net-user.c
> index 2934d1c..b77c9b3 100644
> --- a/lib/librte_vhost/vhost_user/virtio-net-user.c
> +++ b/lib/librte_vhost/vhost_user/virtio-net-user.c
> @@ -365,3 +365,51 @@ user_set_protocol_features(struct vhost_device_ctx ctx,
>  
>  	dev->protocol_features = protocol_features;
>  }
> +
> +int
> +user_set_log_base(struct vhost_device_ctx ctx,
> +		 struct VhostUserMsg *msg)
> +{
> +	struct virtio_net *dev;
> +	int fd = msg->fds[0];
> +	uint64_t size, off;
> +	void *addr;
> +
> +	dev = get_device(ctx);
> +	if (!dev)
> +		return -1;
> +
> +	if (fd < 0) {
> +		RTE_LOG(ERR, VHOST_CONFIG, "invalid log fd: %d\n", fd);
> +		return -1;
> +	}
> +
> +	if (msg->size != sizeof(VhostUserLog)) {
> +		RTE_LOG(ERR, VHOST_CONFIG,
> +			"invalid log base msg size: %"PRId32" != %d\n",
> +			msg->size, (int)sizeof(VhostUserLog));
> +		return -1;
> +	}
> +
> +	size = msg->payload.log.mmap_size;
> +	off  = msg->payload.log.mmap_offset;
> +	RTE_LOG(INFO, VHOST_CONFIG,
> +		"log mmap size: %"PRId64", offset: %"PRId64"\n",
> +		size, off);
> +
> +	/*
> +	 * mmap from 0 to workaround a hugepage mmap bug: mmap will be
> +	 * failed when offset is not page size aligned.
> +	 */
s /will be failed/will fail/
mmap will fail when offset is not zero.
Also we only know this workaround is for hugetlbfs. Not sure of other
tmpfs, so mention hugetlbfs here.
> +	addr = mmap(0, size + off, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
> +	if (addr == MAP_FAILED) {
> +		RTE_LOG(ERR, VHOST_CONFIG, "mmap log base failed!\n");
> +		return -1;
> +	}
> +
> +	/* TODO: unmap on stop */
> +	dev->log_base = (uint64_t)(uintptr_t)addr + off;
(uint64_t)(uintptr_t)RTE_PTR_ADD(addr, off)?
> +	dev->log_size = size;
> +
> +	return 0;
> +}
> diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.h b/lib/librte_vhost/vhost_user/virtio-net-user.h
> index b82108d..013cf38 100644
> --- a/lib/librte_vhost/vhost_user/virtio-net-user.h
> +++ b/lib/librte_vhost/vhost_user/virtio-net-user.h
> @@ -49,6 +49,7 @@ void user_set_vring_kick(struct vhost_device_ctx, struct VhostUserMsg *);
>  
>  void user_set_protocol_features(struct vhost_device_ctx ctx,
>  				uint64_t protocol_features);
> +int user_set_log_base(struct vhost_device_ctx ctx, struct VhostUserMsg *);
>  
>  int user_get_vring_base(struct vhost_device_ctx, struct vhost_vring_state *);
>