On 10/24/2022 7:24 PM, Jason Wang wrote:
On Tue, Oct 25, 2022 at 3:14 AM Si-Wei Liu <si-wei.liu@oracle.com> wrote:



On 10/24/2022 1:40 AM, Jason Wang wrote:

On Sat, Oct 22, 2022 at 7:49 AM Si-Wei Liu <si-wei.liu@oracle.com> wrote:

Live migration of vdpa would typically require re-instate vdpa
device with an idential set of configs on the destination node,
same way as how source node created the device in the first
place. In order to save orchestration software from memorizing
and keeping track of vdpa config, it will be helpful if the vdpa
tool provides the aids for exporting the initial configs as-is,
the way how vdpa device was created. The "vdpa dev show" command
seems to be the right vehicle for that. It is unlike the "vdpa dev
config show" command output which usually goes with the live value
in the device config space, and is not quite reliable subject to
the dynamics of feature negotiation or possible change by the
driver to the config space.

Examples:

1) Create vDPA by default without any config attribute

$ vdpa dev add mgmtdev pci/0000:41:04.2 name vdpa0
$ vdpa dev show vdpa0
vdpa0: type network mgmtdev pci/0000:41:04.2 vendor_id 5555 max_vqs 9 max_vq_size 256
$ vdpa dev -jp show vdpa0
{
     "dev": {
         "vdpa0": {
             "type": "network",
             "mgmtdev": "pci/0000:41:04.2",
             "vendor_id": 5555,
             "max_vqs": 9,
             "max_vq_size": 256,
         }
     }
}

2) Create vDPA with config attribute(s) specified

$ vdpa dev add mgmtdev pci/0000:41:04.2 name vdpa0 \
     mac e4:11:c6:d3:45:f0 max_vq_pairs 4
$ vdpa dev show
vdpa0: type network mgmtdev pci/0000:41:04.2 vendor_id 5555 max_vqs 9 max_vq_size 256
   initial_config: mac e4:11:c6:d3:45:f0 max_vq_pairs 4
$ vdpa dev -jp show
{
     "dev": {
         "vdpa0": {
             "type": "network",
             "mgmtdev": "pci/0000:41:04.2",
             "vendor_id": 5555,
             "max_vqs": 9,
             "max_vq_size": 256,
             "initial_config": {
                 "mac": "e4:11:c6:d3:45:f0",
                 "max_vq_pairs": 4
             }
         }
     }
}

Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
---
  drivers/vdpa/vdpa.c | 39 +++++++++++++++++++++++++++++++++++++++
  1 file changed, 39 insertions(+)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index bebded6..bfb8f54 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -677,6 +677,41 @@ static int vdpa_nl_cmd_dev_del_set_doit(struct sk_buff *skb, struct genl_info *i
  }

  static int
+vdpa_dev_initcfg_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 device_id)
+{
+       struct vdpa_dev_set_config *cfg = &vdev->init_cfg;
+       int err = -EMSGSIZE;
+
+       if (!cfg->mask)
+               return 0;
+
+       switch (device_id) {
+       case VIRTIO_ID_NET:
+               if ((cfg->mask & BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MACADDR)) != 0 &&
+                   nla_put(msg, VDPA_ATTR_DEV_NET_CFG_MACADDR,
+                           sizeof(cfg->net.mac), cfg->net.mac))
+                       return err;
+               if ((cfg->mask & BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MTU)) != 0 &&
+                   nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, cfg->net.mtu))
+                       return err;
+               if ((cfg->mask & BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MAX_VQP)) != 0 &&
+                   nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MAX_VQP,
+                               cfg->net.max_vq_pairs))
+                       return err;
+               break;
+       default:
+               break;
+       }
+
+       if ((cfg->mask & BIT_ULL(VDPA_ATTR_DEV_FEATURES)) != 0 &&
+           nla_put_u64_64bit(msg, VDPA_ATTR_DEV_FEATURES,
+                             cfg->device_features, VDPA_ATTR_PAD))
+               return err;

A question: If any of those above attributes were not provisioned,
should we show the ones that are inherited from the parent?

A simple answer would be yes, but the long answer is that I am not sure
if there's any for the moment - there's no  default value for mtu, mac,
and max_vqp that can be inherited from the parent (max_vqp by default
being 1 is spec defined, not something inherited from the parent).

Note that it is by default from driver level that if _F_MQ is not
negotiated. But I think we are talking about something different that
is out of the spec here, what if:

vDPA inherit _F_MQ but mqx_vqp is not provisioned via netlink.

Or is it not allowed?
My understanding is that this is not allowed any more since the introduction of max_vqp attribute. Noted, currently we don't have a way for vendor driver to report the default value for mqx_vqp, if not otherwise specified in the CLI. Without getting the default value reported in 'vdpa mgmtdev show' level, it'd just confuse mgmt software even more.

  At least some time in the past, mlx5 were
enabled with MQ with 8 queue pairs by default.
That was the situation when there's no max_vqp attribute support from vdpa netlink API level. I think now every driver honors the vdpa core disposition to get a single queue pair if max_vqp config is missing.  And the mlx5_vdpa driver with 8 queue pairs in the wild days is just irrelevant to be manageable by mgmt software, regardless of live migration.


And
the device_features if inherited is displayed at 'vdpa dev config show'
output. Can you remind me of a good example for inherited value that we
may want to show here?

Some other cases:

1) MTU: there should be something that the device needs to report if
_F_MTU is negotiated even if it is not provisioned from netlink.
I am not sure I understand the ask here. Noted the QEMU argument has to offer host_mtu=X with the maximum MTU value for guest to use (and applied as the initial MTU config during virtio-net probing for Linux driver), and the way to get the parent device MTU and whether that's relevant to vdpa device's MTU is very vendor specific. I think we would need new attribute(s) in the mgmtdev level to support what you want here?

2) device_features: if device_features is not provisioned, we should
still report it via netlink here
Not the way I expected it, but with Lingshan's series to expose fields out of FEATURES_OK, the device_features is now reported through 'vdpa dev config show' regardless being specified or not, if I am not mistaken?

Currently we export the config attributes upon vdpa creation under the "initial_config" key. If we want to expose more default values inherited from mgmtdev, I think we can wrap up these default values under another key "inherited_config" to display in 'vdpa dev show' output. Does it fit what you have in mind?

or do you mean the mgmt can assume it
should be the same as mgmtdev. Anyhow if we don't show device_features
if it is not provisioned, it will complicate the mgmt software.
Yes, as I said earlier, since the device_features attr getting added to the 'vdpa dev config show' command, this divergence started to complicate mgmt software already.

Thanks,
-Siwei

Thanks



Thanks,
-Siwei



Thanks


+
+       return 0;
+}
+
+static int
  vdpa_dev_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, u32 seq,
               int flags, struct netlink_ext_ack *extack)
  {
@@ -715,6 +750,10 @@ static int vdpa_nl_cmd_dev_del_set_doit(struct sk_buff *skb, struct genl_info *i
         if (nla_put_u16(msg, VDPA_ATTR_DEV_MIN_VQ_SIZE, min_vq_size))
                 goto msg_err;

+       err = vdpa_dev_initcfg_fill(vdev, msg, device_id);
+       if (err)
+               goto msg_err;
+
         genlmsg_end(msg, hdr);
         return 0;

--
1.8.3.1