Re: [PATCH v2 4/4] vdpa: Support reading device features

On Mon, Feb 21, 2022 at 12:18:03PM +0800, Jason Wang wrote:

在 2022/2/17 下午8:30, Eli Cohen 写道:

quoted

When showing the available management devices, check if
VDPA_ATTR_DEV_SUPPORTED_FEATURES feature is available and print the
supported features for a management device.

Examples:
$ vdpa mgmtdev show
auxiliary/mlx5_core.sf.1:
   supported_classes net
   max_supported_vqs 257
   dev_features CSUM GUEST_CSUM MTU HOST_TSO4 HOST_TSO6 STATUS CTRL_VQ MQ \
                CTRL_MAC_ADDR VERSION_1 ACCESS_PLATFORM

$ vdpa -jp mgmtdev show
{
     "mgmtdev": {
         "auxiliary/mlx5_core.sf.1": {
             "supported_classes": [ "net" ],
             "max_supported_vqs": 257,
             "dev_features": [
"CSUM","GUEST_CSUM","MTU","HOST_TSO4","HOST_TSO6","STATUS","CTRL_VQ","MQ",\
"CTRL_MAC_ADDR","VERSION_1","ACCESS_PLATFORM" ]
         }
     }
}

Reviewed-by: Si-Wei Liu <redacted>
Signed-off-by: Eli Cohen <redacted>
---
  vdpa/include/uapi/linux/vdpa.h |  1 +
  vdpa/vdpa.c                    | 14 +++++++++++++-
  2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/vdpa/include/uapi/linux/vdpa.h b/vdpa/include/uapi/linux/vdpa.h
index a3ebf4d4d9b8..96ccbf305d14 100644
--- a/vdpa/include/uapi/linux/vdpa.h
+++ b/vdpa/include/uapi/linux/vdpa.h

@@ -42,6 +42,7 @@ enum vdpa_attr {
  	VDPA_ATTR_DEV_NEGOTIATED_FEATURES,	/* u64 */
  	VDPA_ATTR_DEV_MGMTDEV_MAX_VQS,          /* u32 */
+	VDPA_ATTR_DEV_SUPPORTED_FEATURES,	/* u64 */
  	/* new attributes must be added above here */
  	VDPA_ATTR_MAX,

diff --git a/vdpa/vdpa.c b/vdpa/vdpa.c
index 78736b1422b6..bdc366880ab9 100644
--- a/vdpa/vdpa.c
+++ b/vdpa/vdpa.c

@@ -84,6 +84,7 @@ static const enum mnl_attr_data_type vdpa_policy[VDPA_ATTR_MAX + 1] = {
  	[VDPA_ATTR_DEV_MAX_VQ_SIZE] = MNL_TYPE_U16,
  	[VDPA_ATTR_DEV_NEGOTIATED_FEATURES] = MNL_TYPE_U64,
  	[VDPA_ATTR_DEV_MGMTDEV_MAX_VQS] = MNL_TYPE_U32,
+	[VDPA_ATTR_DEV_SUPPORTED_FEATURES] = MNL_TYPE_U64,
  };
  static int attr_cb(const struct nlattr *attr, void *data)

@@ -494,13 +495,14 @@ static void print_features(struct vdpa *vdpa, uint64_t features, bool mgmtdevf,
  static void pr_out_mgmtdev_show(struct vdpa *vdpa, const struct nlmsghdr *nlh,
  				struct nlattr **tb)
  {
+	uint64_t classes = 0;
  	const char *class;
  	unsigned int i;
  	pr_out_handle_start(vdpa, tb);
  	if (tb[VDPA_ATTR_MGMTDEV_SUPPORTED_CLASSES]) {
-		uint64_t classes = mnl_attr_get_u64(tb[VDPA_ATTR_MGMTDEV_SUPPORTED_CLASSES]);
+		classes = mnl_attr_get_u64(tb[VDPA_ATTR_MGMTDEV_SUPPORTED_CLASSES]);
  		pr_out_array_start(vdpa, "supported_classes");
  		for (i = 1; i < 64; i++) {

@@ -522,6 +524,16 @@ static void pr_out_mgmtdev_show(struct vdpa *vdpa, const struct nlmsghdr *nlh,
  		print_uint(PRINT_ANY, "max_supported_vqs", "  max_supported_vqs %d", num_vqs);
  	}
+	if (tb[VDPA_ATTR_DEV_SUPPORTED_FEATURES]) {
+		uint64_t features;
+
+		features  = mnl_attr_get_u64(tb[VDPA_ATTR_DEV_SUPPORTED_FEATURES]);
+		if (classes & BIT(VIRTIO_ID_NET))
+			print_features(vdpa, features, true, VIRTIO_ID_NET);
+		else
+			print_features(vdpa, features, true, 0);

I wonder what happens if we try to read a virtio_blk device consider:

static const char * const *dev_to_feature_str[] = {
        [VIRTIO_ID_NET] = net_feature_strs,
};

In that case we will print bit_xx for each non general bit.

Thanks

quoted

+	}
+
  	pr_out_handle_end(vdpa);
  }