On 2020/5/18 上午11:09, Wang, Xiao W wrote:
Hi,
Comments inline.
Best Regards,
Xiao
-----Original Message-----
From: Jason Wang<[email protected]>
Sent: Friday, May 15, 2020 6:09 PM
To: Wang, Xiao W<[email protected]>; Maxime Coquelin
<[email protected]>; Ye, Xiaolong<[email protected]>;
[email protected];[email protected];[email protected];
[email protected];[email protected]
Cc:[email protected]; Xu, Rosen<[email protected]>
Subject: Re: [PATCH 3/9] vdpa/ifc: add support to vDPA queue enable
On 2020/5/15 下午5:42, Wang, Xiao W wrote:
Hi,
Best Regards,
Xiao
-----Original Message-----
From: Jason Wang<[email protected]>
Sent: Friday, May 15, 2020 5:09 PM
To: Maxime Coquelin<[email protected]>; Ye, Xiaolong
<[email protected]>;[email protected];[email protected];
[email protected]; Wang, Xiao W<[email protected]>;
[email protected];[email protected]
Cc:[email protected]
Subject: Re: [PATCH 3/9] vdpa/ifc: add support to vDPA queue enable
On 2020/5/14 下午4:02, Maxime Coquelin wrote:
This patch adds support to enabling and disabling
vrings on a per-vring granularity.
Signed-off-by: Maxime Coquelin <[email protected]
<mailto:[email protected]>>
A question here, I see in qemu peer_attach() may try to generate
VHOST_USER_SET_VRING_ENABLE, but just from the name I think it should
behave as queue_enable defined in virtio specification which is
explicitly under the control of guest?
(Note, in Cindy's vDPA series, we must invent new vhost_ops to differ
from this one).
From my view, common_cfg.enable reg is used for registering a queue to
hypervisor&vhost, but not ENABLE.
Well, what's your definition of "enable" in this context?
"Enable a queue" means traffic can pass through this queue.
Spec said:
queue_enable
The driver uses this to selectively prevent the device from
executing requests from this virtqueue. 1 - enabled; 0 - disabled.
This means, if queue_enable is not set to 1, device can not execute
request for this specific virtqueue.
For queue enabling in virtio MQ case, there're 2 steps needed:
1. select a queue and write 1 to common_cfg.enable reg
Note that:
1) queue_enable doesn't mean you can disable a queue by writing zero to
that (which is not allowed by the spec)
2) queue_enable is not specific to MQ, you need write 1 to all the
queues that will be used by this driver
3) it's not allowed to write 1 to queue_enable after DRIVER_OK
2. send control vq message VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET
If no step2, by default there's only 1 queue pair enabled.
Yes, and if you read the git history. This command is invented by me :)
Thanks
