On 2/26/19 9:42 AM, Ilya Maximets wrote:
On 26.02.2019 11:13, Liu, Changpeng wrote:
-----Original Message-----
From: Ilya Maximets [mailto:i.maxim...@samsung.com]
Sent: Tuesday, February 26, 2019 3:39 PM
To: Liu, Changpeng <changpeng....@intel.com>; dev@dpdk.org
Cc: Stojaczyk, Dariusz <dariusz.stojac...@intel.com>;
maxime.coque...@redhat.com; Bie, Tiwei <tiwei....@intel.com>; Wang,
Zhihong <zhihong.w...@intel.com>; Jason Wang <jasow...@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.maxim...@samsung.com]
Sent: Monday, February 25, 2019 9:20 PM
To: Liu, Changpeng <changpeng....@intel.com>; dev@dpdk.org
Cc: Stojaczyk, Dariusz <dariusz.stojac...@intel.com>;
maxime.coque...@redhat.com; Bie, Tiwei <tiwei....@intel.com>; Wang,
Zhihong <zhihong.w...@intel.com>; Jason Wang <jasow...@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.
+1
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 ?
I would prefer it to be implemented in SPDK directly as a pre_handler
callback, as I don't foresee a need for it for other backends, and it
would avoid breaking the API.
It would imply fixing the beginning of vhost_user_msg_handler() to
accept requests > VHOST_USER_MAX and add necessary check before doing
the debug logs.
With above change we would also be able to remove VHOST_CRYPTO requests
from vhost_user.c, and we could then work on moving vhost-net bits
out of this file too.
Regards,
Maxime
