netdev - Re: [PATCH 1/4] vDPA: allow userspace to query features of a vDPA device

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Date:   Tue, 20 Sep 2022 17:58:33 +0800
From:   "Zhu, Lingshan" <lingshan.zhu@...el.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     mst <mst@...hat.com>,
        virtualization <virtualization@...ts.linux-foundation.org>,
        netdev <netdev@...r.kernel.org>, kvm <kvm@...r.kernel.org>
Subject: Re: [PATCH 1/4] vDPA: allow userspace to query features of a vDPA
 device



On 9/20/2022 10:02 AM, Jason Wang wrote:
> On Fri, Sep 9, 2022 at 5:05 PM Zhu Lingshan <lingshan.zhu@...el.com> wrote:
>> This commit adds a new vDPA netlink attribution
>> VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES. Userspace can query
>> features of vDPA devices through this new attr.
>>
>> This commit invokes vdpa_config_ops.get_config() than
>> vdpa_get_config_unlocked() to read the device config
>> spcae, so no raeces in vdpa_set_features_unlocked()
>>
>> Signed-off-by: Zhu Lingshan <lingshan.zhu@...el.com>
> It's better to share the userspace code as well.
OK, will share it in V2.
>
>> ---
>>   drivers/vdpa/vdpa.c       | 19 ++++++++++++++-----
>>   include/uapi/linux/vdpa.h |  4 ++++
>>   2 files changed, 18 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
>> index c06c02704461..798a02c7aa94 100644
>> --- a/drivers/vdpa/vdpa.c
>> +++ b/drivers/vdpa/vdpa.c
>> @@ -491,6 +491,8 @@ static int vdpa_mgmtdev_fill(const struct vdpa_mgmt_dev *mdev, struct sk_buff *m
>>                  err = -EMSGSIZE;
>>                  goto msg_err;
>>          }
>> +
>> +       /* report features of a vDPA management device through VDPA_ATTR_DEV_SUPPORTED_FEATURES */
> The code explains itself, there's no need for the comment.
these comments are required in other discussions
>
>>          if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_SUPPORTED_FEATURES,
>>                                mdev->supported_features, VDPA_ATTR_PAD)) {
>>                  err = -EMSGSIZE;
>> @@ -815,10 +817,10 @@ static int vdpa_dev_net_mq_config_fill(struct vdpa_device *vdev,
>>   static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *msg)
>>   {
>>          struct virtio_net_config config = {};
>> -       u64 features;
>> +       u64 features_device, features_driver;
>>          u16 val_u16;
>>
>> -       vdpa_get_config_unlocked(vdev, 0, &config, sizeof(config));
>> +       vdev->config->get_config(vdev, 0, &config, sizeof(config));
>>
>>          if (nla_put(msg, VDPA_ATTR_DEV_NET_CFG_MACADDR, sizeof(config.mac),
>>                      config.mac))
>> @@ -832,12 +834,19 @@ static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *ms
>>          if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, val_u16))
>>                  return -EMSGSIZE;
>>
>> -       features = vdev->config->get_driver_features(vdev);
>> -       if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES, features,
>> +       features_driver = vdev->config->get_driver_features(vdev);
>> +       if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES, features_driver,
>> +                             VDPA_ATTR_PAD))
>> +               return -EMSGSIZE;
>> +
>> +       features_device = vdev->config->get_device_features(vdev);
>> +
>> +       /* report features of a vDPA device through VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES */
>> +       if (nla_put_u64_64bit(msg, VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES, features_device,
>>                                VDPA_ATTR_PAD))
>>                  return -EMSGSIZE;
>>
>> -       return vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
>> +       return vdpa_dev_net_mq_config_fill(vdev, msg, features_driver, &config);
>>   }
>>
>>   static int
>> diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h
>> index 25c55cab3d7c..97531b52dcbe 100644
>> --- a/include/uapi/linux/vdpa.h
>> +++ b/include/uapi/linux/vdpa.h
>> @@ -46,12 +46,16 @@ enum vdpa_attr {
>>
>>          VDPA_ATTR_DEV_NEGOTIATED_FEATURES,      /* u64 */
>>          VDPA_ATTR_DEV_MGMTDEV_MAX_VQS,          /* u32 */
>> +       /* features of a vDPA management device */
>>          VDPA_ATTR_DEV_SUPPORTED_FEATURES,       /* u64 */
>>
>>          VDPA_ATTR_DEV_QUEUE_INDEX,              /* u32 */
>>          VDPA_ATTR_DEV_VENDOR_ATTR_NAME,         /* string */
>>          VDPA_ATTR_DEV_VENDOR_ATTR_VALUE,        /* u64 */
>>
>> +       /* features of a vDPA device, e.g., /dev/vhost-vdpa0 */
>> +       VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES,  /* u64 */
> What's the difference between this and VDPA_ATTR_DEV_SUPPORTED_FEATURES?
This is to report a vDPA device features, and 
VDPA_ATTR_DEV_SUPPORTED_FEATURES
is used for reporting the management device features, we have a long 
discussion
on this before.
>
> Thanks
>
>> +
>>          /* new attributes must be added above here */
>>          VDPA_ATTR_MAX,
>>   };
>> --
>> 2.31.1
>>