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

On 8/16/2022 2:15 AM, Si-Wei Liu wrote:

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

quoted

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 <redacted>
---
  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.

OK, will fix it in V2

-Siwei

quoted

VDPA_ATTR_DEV_QUEUE_INDEX,              /* u32 */
      VDPA_ATTR_DEV_VENDOR_ATTR_NAME,        /* string */