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

[Ilya Maximets <i.maximets@samsung.com>]

On 26.02.2019 11:13, Liu, Changpeng wrote:
> 
> 
>> -----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.

So, maybe it's time to reconsider the implementation.

> The get_config/set_config was defined for all the virtio devices, so I think it makes
> more sense adding here.

VHOST_USER_*_CRYPTO_SESSION messages are defined for all the virtio devices
too, however they makes sense for vhost_crypto backend only. These messages
(GET/SET_CONFIG) makes sense only when callbacks (get/set_config) are
implemented, so IMHO it's better to implement their handlers along with the
callbacks, i.e. inside the implementation of your vhost backend.

Maxime, Tiwei, what do you think ?

>>
>>
>>>>
>>>> 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;
>>>>>