Messages in this thread | | | From | Eli Cohen <> | Subject | RE: [PATCH] vdpa: Warn if MTU configured is too low | Date | Wed, 11 May 2022 10:53:40 +0000 |
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> -----Original Message----- > From: Jason Wang <jasowang@redhat.com> > Sent: Wednesday, May 11, 2022 1:19 PM > To: Eli Cohen <elic@nvidia.com> > Cc: mst <mst@redhat.com>; virtualization <virtualization@lists.linux-foundation.org>; linux-kernel <linux-kernel@vger.kernel.org>; Si- > Wei Liu <si-wei.liu@oracle.com> > Subject: Re: [PATCH] vdpa: Warn if MTU configured is too low > > On Wed, May 11, 2022 at 6:02 PM Eli Cohen <elic@nvidia.com> wrote: > > > > > From: Jason Wang <jasowang@redhat.com> > > > Sent: Wednesday, May 11, 2022 12:34 PM > > > To: Eli Cohen <elic@nvidia.com> > > > Cc: mst <mst@redhat.com>; virtualization <virtualization@lists.linux-foundation.org>; linux-kernel <linux-kernel@vger.kernel.org>; Si- > > > Wei Liu <si-wei.liu@oracle.com> > > > Subject: Re: [PATCH] vdpa: Warn if MTU configured is too low > > > > > > On Wed, May 11, 2022 at 4:48 PM Eli Cohen <elic@nvidia.com> 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@nvidia.com> > > > > > > I wonder why it's a must? > > > > It's definitely not a must but I thought if the spec says "should" it deserves a warning > > Right. > > > but we can drop this if you think the warning is not in place. > > I remember netlink has an extra log buffer, I wonder if it's better to > warn there? >
You mean use NL_SET_ERR_MSG_MOD(info->extack, "MTU is below recommended value\n") ? dmesg stays clean but the user gets a warning
> > > > > > > > > --- > > > > 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..961168fe9094 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 */ > > > > +#define VIRTIO_MIN_PREFERRED_MTU 1280 > > > > + > > > > 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)) > > > > > > Should be <= ? > > > > I don't think so. If it equals 1280 you don't want to warn. > > Yes, you're right. > > Thanks > > > > > > > > > Thanks > > > > > > > + pr_warn("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"); > > > > @@ -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 > > > > > >
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