Re: [PATCH 1/2] vDPA: allow userspace to query features of a vDPA device

[Si-Wei Liu]

On 8/15/2022 2:26 AM, Zhu Lingshan 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.

Signed-off-by: Zhu Lingshan <lingshan....@intel.com>
---
  drivers/vdpa/vdpa.c       | 17 +++++++++++++----
  include/uapi/linux/vdpa.h |  3 +++
  2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index c06c02704461..efb55a06e961 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 */
        if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_SUPPORTED_FEATURES,
                              mdev->supported_features, VDPA_ATTR_PAD)) {
                err = -EMSGSIZE;
@@ -815,7 +817,7 @@ 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));

@@ -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..d171b92ef522 100644
--- a/include/uapi/linux/vdpa.h
+++ b/include/uapi/linux/vdpa.h
@@ -46,7 +46,10 @@ 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 */
+       /* features of a vDPA device, e.g., /dev/vhost-vdpa0 */
+       VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES,  /* u64 */

Append to the end, please. Otherwise it breaks userspace ABI.

-Siwei

VDPA_ATTR_DEV_QUEUE_INDEX, /* u32 */

        VDPA_ATTR_DEV_VENDOR_ATTR_NAME,         /* string */

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