Re: [dpdk-dev] vhost: add virtio configuration space access socket messages

["Liu, Changpeng" <changpeng.liu@intel.com>]

> -----Original Message-----
> From: Ilya Maximets [mailto:i.maximets@samsung.com]
> Sent: Tuesday, February 26, 2019 3:39 PM
> To: Liu, Changpeng <changpeng.liu@intel.com>; dev@dpdk.org
> Cc: Stojaczyk, Dariusz <dariusz.stojaczyk@intel.com>;
> maxime.coquelin@redhat.com; Bie, Tiwei <tiwei.bie@intel.com>; Wang,
> Zhihong <zhihong.wang@intel.com>; Jason Wang <jasowang@redhat.com>
> Subject: Re: vhost: add virtio configuration space access socket messages
> 
> On 26.02.2019 10:01, Liu, Changpeng wrote:
> >
> >
> >> -----Original Message-----
> >> From: Ilya Maximets [mailto:i.maximets@samsung.com]
> >> Sent: Monday, February 25, 2019 9:20 PM
> >> To: Liu, Changpeng <changpeng.liu@intel.com>; dev@dpdk.org
> >> Cc: Stojaczyk, Dariusz <dariusz.stojaczyk@intel.com>;
> >> maxime.coquelin@redhat.com; Bie, Tiwei <tiwei.bie@intel.com>; Wang,
> >> Zhihong <zhihong.wang@intel.com>; Jason Wang <jasowang@redhat.com>
> >> Subject: Re: vhost: add virtio configuration space access socket messages
> >>
> >> On 25.02.2019 10:51, Changpeng Liu wrote:
> >>> This patch adds new vhost user messages GET_CONFIG and SET_CONFIG
> >>> used to get/set virtio device's PCI configuration space.
> >>
> >> Beside the fact that some additional description and reasoning required,
> >> I do not see the usage of this feature. You're defining the flag
> >> VHOST_USER_PROTOCOL_F_CONFIG, but it's never used. So, none of dpdk
> vhost
> >> backends (vdpa, vhost-user) will use this feature.
> >> You, probably, missed adding it to VHOST_USER_PROTOCOL_FEATURES or
> >> VDPA_SUPPORTED_PROTOCOL_FEATURES.
> >>
> >> From the other side, current implementation forces application to properly
> >> implement the get/set_config callbacks. Otherwise, receiving of the messages
> >> will result in RTE_VHOST_MSG_RESULT_ERR and subsequent vhost
> >> disconnection.
> >> This looks strange, because supported protocol features normally enabled by
> >> default. Am I misunderstood something ?
> > QEMU will not send the messages if VHOST_USER_PROTOCOL_F_CONFIG
> wasn't enabled.
> 
> So, you're going to enable it only by explicit call to
> 'rte_vhost_driver_set_features' ?
> 
> In this case I'm assuming that you're implementing your own vhost backend.
> But why you're not using 'dev->extern_ops' and corresponding 'pre_msg_handle'
> or 'post_msg_handle' to handle your GET/SET_CONFIG messages like it does
> 'vhost_crypto' backend ?
The patch was developed one year ago, while DPDK didn't have external ops.
The get_config/set_config was defined for all the virtio devices, so I think it makes
more sense adding here.
> 
> 
> >>
> >> One more thing. According to spec: "vhost-user slave uses zero length of
> >> payload to indicate an error to vhost-user master". However, current version
> >> of 'vhost_user_get_config' replies with size equal to 'sizeof(uint64_t)'.
> > Yeah, can be changed to 0 here, QEMU can process it.
> >>
> >> Best regards, Ilya Maximets.
> >>
> >>> Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
> >>> Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
> >>> ---
> >>>  lib/librte_vhost/rte_vhost.h  |  8 ++++++++
> >>>  lib/librte_vhost/vhost_user.c | 44
> >> +++++++++++++++++++++++++++++++++++++++++++
> >>>  lib/librte_vhost/vhost_user.h | 16 ++++++++++++++++
> >>>  3 files changed, 68 insertions(+)
> >>>
> >>> diff --git a/lib/librte_vhost/rte_vhost.h b/lib/librte_vhost/rte_vhost.h
> >>> index 2753670..ab710ce 100644
> >>> --- a/lib/librte_vhost/rte_vhost.h
> >>> +++ b/lib/librte_vhost/rte_vhost.h
> >>> @@ -63,6 +63,10 @@
> >>>  #define VHOST_USER_PROTOCOL_F_PAGEFAULT 8
> >>>  #endif
> >>>
> >>> +#ifndef VHOST_USER_PROTOCOL_F_CONFIG
> >>> +#define VHOST_USER_PROTOCOL_F_CONFIG 9
> >>> +#endif
> >>> +
> >>>  #ifndef VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD
> >>>  #define VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD 10
> >>>  #endif
> >>> @@ -173,6 +177,10 @@ struct vhost_device_ops {
> >>>
> >>>  	int (*vring_state_changed)(int vid, uint16_t queue_id, int enable);
> >> 	/**< triggered when a vring is enabled or disabled */
> >>>
> >>> +	int (*get_config)(int vid, uint8_t *config, uint32_t config_len>>> +
> 	int (*set_config)(int vid, uint8_t *config, uint32_t offset,
> >>> +			  uint32_t len, uint32_t flags);
> >>> +
> >>>  	/**
> >>>  	 * Features could be changed after the feature negotiation.
> >>>  	 * For example, VHOST_F_LOG_ALL will be set/cleared at the
> >>> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> >>> index b086ad9..8e42734 100644
> >>> --- a/lib/librte_vhost/vhost_user.c
> >>> +++ b/lib/librte_vhost/vhost_user.c
> >>> @@ -73,6 +73,8 @@
> >>>  	[VHOST_USER_NET_SET_MTU]  = "VHOST_USER_NET_SET_MTU",
> >>>  	[VHOST_USER_SET_SLAVE_REQ_FD]  =
> >> "VHOST_USER_SET_SLAVE_REQ_FD",
> >>>  	[VHOST_USER_IOTLB_MSG]  = "VHOST_USER_IOTLB_MSG",
> >>> +	[VHOST_USER_GET_CONFIG] = "VHOST_USER_GET_CONFIG",
> >>> +	[VHOST_USER_SET_CONFIG] = "VHOST_USER_SET_CONFIG",
> >>>  	[VHOST_USER_CRYPTO_CREATE_SESS] =
> >> "VHOST_USER_CRYPTO_CREATE_SESS",
> >>>  	[VHOST_USER_CRYPTO_CLOSE_SESS] =
> >> "VHOST_USER_CRYPTO_CLOSE_SESS",
> >>>  	[VHOST_USER_POSTCOPY_ADVISE]  = "VHOST_USER_POSTCOPY_ADVISE",
> >>> @@ -359,6 +361,46 @@
> >>>  	return RTE_VHOST_MSG_RESULT_OK;
> >>>  }
> >>>
> >>> +static int
> >>> +vhost_user_get_config(struct virtio_net **pdev, struct VhostUserMsg *msg,
> >>> +		      int main_fd __rte_unused)
> >>> +{
> >>> +	struct virtio_net *dev = *pdev;
> >>> +
> >>> +	if (!dev->notify_ops->get_config) {
> >>> +		msg->size = sizeof(uint64_t);
> >>> +		return RTE_VHOST_MSG_RESULT_REPLY;
> >>> +	}
> >>> +
> >>> +	if (dev->notify_ops->get_config(dev->vid,
> >>> +					msg->payload.config.region,
> >>> +					msg->payload.config.size) != 0) {
> >>> +		msg->size = sizeof(uint64_t);
> >>> +	}
> >>> +
> >>> +	return RTE_VHOST_MSG_RESULT_REPLY;
> >>> +}
> >>> +
> >>> +static int
> >>> +vhost_user_set_config(struct virtio_net **pdev, struct VhostUserMsg *msg,
> >>> +		      int main_fd __rte_unused)
> >>> +{
> >>> +	struct virtio_net *dev = *pdev;
> >>> +
> >>> +	if (!dev->notify_ops->set_config)
> >>> +		return RTE_VHOST_MSG_RESULT_ERR;
> >>> +
> >>> +	if (dev->notify_ops->set_config(dev->vid,
> >>> +					msg->payload.config.region,
> >>> +					msg->payload.config.offset,
> >>> +					msg->payload.config.size,
> >>> +					msg->payload.config.flags) != 0) {
> >>> +		return RTE_VHOST_MSG_RESULT_ERR;
> >>> +	}
> >>> +
> >>> +	return RTE_VHOST_MSG_RESULT_OK;
> >>> +}
> >>> +
> >>>  /*
> >>>   * Reallocate virtio_dev and vhost_virtqueue data structure to make them
> on
> >> the
> >>>   * same numa node as the memory of vring descriptor.
> >>> @@ -1725,6 +1767,8 @@ typedef int (*vhost_message_handler_t)(struct
> >> virtio_net **pdev,
> >>>  	[VHOST_USER_NET_SET_MTU] = vhost_user_net_set_mtu,
> >>>  	[VHOST_USER_SET_SLAVE_REQ_FD] = vhost_user_set_req_fd,
> >>>  	[VHOST_USER_IOTLB_MSG] = vhost_user_iotlb_msg,
> >>> +	[VHOST_USER_GET_CONFIG] = vhost_user_get_config,
> >>> +	[VHOST_USER_SET_CONFIG] = vhost_user_set_config,
> >>>  	[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,
> >>> diff --git a/lib/librte_vhost/vhost_user.h b/lib/librte_vhost/vhost_user.h
> >>> index 2a650fe..057cdec 100644
> >>> --- a/lib/librte_vhost/vhost_user.h
> >>> +++ b/lib/librte_vhost/vhost_user.h
> >>> @@ -12,6 +12,11 @@
> >>>
> >>>  /* refer to hw/virtio/vhost-user.c */
> >>>
> >>> +/*
> >>> + * Maximum size of virtio device config space
> >>> + */
> >>> +#define VHOST_USER_MAX_CONFIG_SIZE 256
> >>> +
> >>>  #define VHOST_MEMORY_MAX_NREGIONS 8
> >>>
> >>>  #define VHOST_USER_PROTOCOL_FEATURES	((1ULL <<
> >> VHOST_USER_PROTOCOL_F_MQ) | \
> >>> @@ -49,6 +54,8 @@
> >>>  	VHOST_USER_NET_SET_MTU = 20,
> >>>  	VHOST_USER_SET_SLAVE_REQ_FD = 21,
> >>>  	VHOST_USER_IOTLB_MSG = 22,
> >>> +	VHOST_USER_GET_CONFIG = 24,
> >>> +	VHOST_USER_SET_CONFIG = 25,
> >>>  	VHOST_USER_CRYPTO_CREATE_SESS = 26,
> >>>  	VHOST_USER_CRYPTO_CLOSE_SESS = 27,
> >>>  	VHOST_USER_POSTCOPY_ADVISE = 28,
> >>> @@ -60,6 +67,7 @@
> >>>  typedef enum VhostUserSlaveRequest {
> >>>  	VHOST_USER_SLAVE_NONE = 0,
> >>>  	VHOST_USER_SLAVE_IOTLB_MSG = 1,
> >>> +	VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2,
> >>>  	VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG = 3,
> >>>  	VHOST_USER_SLAVE_MAX
> >>>  } VhostUserSlaveRequest;
> >>> @@ -112,6 +120,13 @@
> >>>  	uint64_t offset;
> >>>  } VhostUserVringArea;
> >>>
> >>> +typedef struct VhostUserConfig {
> >>> +	uint32_t offset;
> >>> +	uint32_t size;
> >>> +	uint32_t flags;
> >>> +	uint8_t region[VHOST_USER_MAX_CONFIG_SIZE];
> >>> +} VhostUserConfig;
> >>> +
> >>>  typedef struct VhostUserMsg {
> >>>  	union {
> >>>  		uint32_t master; /* a VhostUserRequest value */
> >>> @@ -131,6 +146,7 @@
> >>>  		struct vhost_vring_addr addr;
> >>>  		VhostUserMemory memory;
> >>>  		VhostUserLog    log;
> >>> +		VhostUserConfig config;
> >>>  		struct vhost_iotlb_msg iotlb;
> >>>  		VhostUserCryptoSessionParam crypto_session;
> >>>  		VhostUserVringArea area;
> >>>