[v1] vdpa: Warn if MTU configured is too low

[PATCH v1] vdpa: Warn if MTU configured is too low

Posted by Eli Cohen 4 years, 1 month ago

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>
---
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 */
+#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))
+		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");
@@ -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

Re: [PATCH v1] vdpa: Warn if MTU configured is too low

Posted by Michael S. Tsirkin 4 years, 1 month ago

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@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

RE: [PATCH v1] vdpa: Warn if MTU configured is too low

Posted by Eli Cohen 4 years, 1 month ago

> -----Original Message-----
> From: Michael S. Tsirkin <mst@redhat.com>
> Sent: Thursday, May 12, 2022 8:57 AM
> To: Eli Cohen <elic@nvidia.com>
> Cc: jasowang@redhat.com; virtualization@lists.linux-foundation.org; linux-kernel@vger.kernel.org; si-wei.liu@oracle.com
> Subject: Re: [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@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.

Sure

> 
> > +#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)?

Will modify

> 
> 
> >  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"
> 
Will change
> 
> > @@ -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

Re: [PATCH v1] vdpa: Warn if MTU configured is too low

Posted by Jason Wang 4 years, 1 month ago

On Wed, May 11, 2022 at 6:56 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>
> ---
> 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 */
> +#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))
> +               NL_SET_ERR_MSG_MOD(info->extack, "MTU is below recommended value\n");

Can this function be used for warning? I have a quick cscope that
tells me it's probably used only for error.

Will it be better if we fail only when the device supports VERSION_1?

Thanks

>         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
>

RE: [PATCH v1] vdpa: Warn if MTU configured is too low

Posted by Eli Cohen 4 years, 1 month ago

> -----Original Message-----
> From: Jason Wang <jasowang@redhat.com>
> Sent: Thursday, May 12, 2022 7:17 AM
> 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 v1] vdpa: Warn if MTU configured is too low
> 
> On Wed, May 11, 2022 at 6:56 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>
> > ---
> > 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 */
> > +#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))
> > +               NL_SET_ERR_MSG_MOD(info->extack, "MTU is below recommended value\n");
> 
> Can this function be used for warning? I have a quick cscope that
> tells me it's probably used only for error.

Here's what I get:
# vdpa dev add name vdpa-a mgmtdev auxiliary/mlx5_core.sf.1 mtu 1279
Warning: vdpa: MTU is below recommended value

The vdpa device is created fine.

> 
> Will it be better if we fail only when the device supports VERSION_1?
> 

Why?

> Thanks
> 
> >         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
> >