Michael S. Tsirkin
2022-May-12 05:57 UTC
[PATCH v1] vdpa: Warn if MTU configured is too low
On Wed, May 11, 2022 at 01:56:42PM +0300, Eli Cohen wrote:> Following the recommendation in virio spec 1.1, a device offering > VIRTIO_NET_F_MTU should set the mtu to at least 1280 bytes. > > Print a warning if this recommendation is not met. > > Signed-off-by: Eli Cohen <elic at nvidia.com> > --- > v0 -> v1: > chage pr_warn to netlink warning to userspace > > drivers/vdpa/vdpa.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c > index 91f4c13c7c7c..0fb4a615f267 100644 > --- a/drivers/vdpa/vdpa.c > +++ b/drivers/vdpa/vdpa.c > @@ -583,6 +583,9 @@ vdpa_nl_cmd_mgmtdev_get_dumpit(struct sk_buff *msg, struct netlink_callback *cb) > BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MTU) | \ > BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MAX_VQP)) > > +/* Recommended virtio spec 1.1 section 5.1.4.1 */I'd add name of section here too.> +#define VIRTIO_MIN_PREFERRED_MTU 1280 > +Preferred is kind of confusing here. I guess you are trying to say it's not mandatory but I don't think this conveys this information. Recommended (matching text below)?> static int vdpa_nl_cmd_dev_add_set_doit(struct sk_buff *skb, struct genl_info *info) > { > struct vdpa_dev_set_config config = {}; > @@ -634,6 +637,10 @@ static int vdpa_nl_cmd_dev_add_set_doit(struct sk_buff *skb, struct genl_info *i > err = PTR_ERR(mdev); > goto err; > } > + if ((mdev->supported_features & BIT_ULL(VIRTIO_NET_F_MTU)) && > + (config.mask & BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MTU) && > + config.net.mtu < VIRTIO_MIN_PREFERRED_MTU)) > + NL_SET_ERR_MSG_MOD(info->extack, "MTU is below recommended value\n"); > if ((config.mask & mdev->config_attr_mask) != config.mask) { > NL_SET_ERR_MSG_MOD(info->extack, > "All provided attributes are not supported");Pity we can't include the actual value here, but oh well. At least let's include the recommended value, we can do that: "MTU is below recommended value of " __stringify(VIRTIO_MIN_PREFERRED_MTU) "\n"> @@ -1135,7 +1142,7 @@ static const struct nla_policy vdpa_nl_policy[VDPA_ATTR_MAX + 1] = { > [VDPA_ATTR_DEV_NAME] = { .type = NLA_STRING }, > [VDPA_ATTR_DEV_NET_CFG_MACADDR] = NLA_POLICY_ETH_ADDR, > /* virtio spec 1.1 section 5.1.4.1 for valid MTU range */ > - [VDPA_ATTR_DEV_NET_CFG_MTU] = NLA_POLICY_MIN(NLA_U16, 68), > + [VDPA_ATTR_DEV_NET_CFG_MTU] = NLA_POLICY_MIN(NLA_U16, ETH_MIN_MTU), > }; > > static const struct genl_ops vdpa_nl_ops[] = { > -- > 2.35.1