[PATCH net v2] i40e: add devlink param to control VF MAC address limit

[PATCH net v2] i40e: add devlink param to control VF MAC address limit

[mheib]

From: Mohammad Heib <mheib@redhat.com>

This patch introduces a new devlink runtime parameter that controls
the maximum number of MAC filters allowed per VF.

The parameter is an integer value. If set to a non-zero number, it is
used as a strict per-VF cap. If left at zero, the driver falls back to
the default limit calculated from the number of allocated VFs and
ports.

This makes the limit policy explicit and configurable by user space,
instead of being only driver internal logic.

Example command to enable per-vf mac limit:
 - devlink dev param set pci/0000:3b:00.0 name max_mac_per_vf \
	value 12 \
	cmode runtime

- Previous discussion about this change:
  https://lore.kernel.org/netdev/20250805134042.2604897-1-dhill@redhat.com

Fixes: cfb1d572c986 ("i40e: Add ensurance of MacVlan resources for every trusted VF")
Signed-off-by: Mohammad Heib <mheib@redhat.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
---
 Documentation/networking/devlink/i40e.rst     | 22 ++++++++
 drivers/net/ethernet/intel/i40e/i40e.h        |  4 ++
 .../net/ethernet/intel/i40e/i40e_devlink.c    | 56 ++++++++++++++++++-
 .../ethernet/intel/i40e/i40e_virtchnl_pf.c    | 25 +++++----
 4 files changed, 95 insertions(+), 12 deletions(-)

diff --git a/Documentation/networking/devlink/i40e.rst b/Documentation/networking/devlink/i40e.rst
index d3cb5bb5197e..f8d5b00bb51d 100644
--- a/Documentation/networking/devlink/i40e.rst
+++ b/Documentation/networking/devlink/i40e.rst
@@ -7,6 +7,28 @@ i40e devlink support
 This document describes the devlink features implemented by the ``i40e``
 device driver.
 
+Parameters
+==========
+
+.. list-table:: Driver specific parameters implemented
+    :widths: 5 5 90
+
+    * - Name
+      - Mode
+      - Description
+    * - ``max_mac_per_vf``
+      - runtime
+      - Controls the maximum number of MAC addresses a VF can use on i40e devices.
+
+        By default (``0``), the driver enforces its internally calculated per-VF
+        MAC filter limit, which is based on the number of allocated VFS.
+
+        If set to a non-zero value, this parameter acts as a strict cap:
+        the driver enforces the maximum of the user-provided value and ignore
+        internally calculated limit.
+
+        The default value is ``0``.
+
 Info versions
 =============
 
diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index 801a57a925da..d2d03db2acec 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -574,6 +574,10 @@ struct i40e_pf {
 	struct i40e_vf *vf;
 	int num_alloc_vfs;	/* actual number of VFs allocated */
 	u32 vf_aq_requests;
+	/* If set to non-zero, the device uses this value
+	 * as maximum number of MAC filters per VF.
+	 */
+	u32 max_mac_per_vf;
 	u32 arq_overflows;	/* Not fatal, possibly indicative of problems */
 	struct ratelimit_state mdd_message_rate_limit;
 	/* DCBx/DCBNL capability for PF that indicates
diff --git a/drivers/net/ethernet/intel/i40e/i40e_devlink.c b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
index cc4e9e2addb7..8532e40b5c7d 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_devlink.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
@@ -5,6 +5,42 @@
 #include "i40e.h"
 #include "i40e_devlink.h"
 
+static int i40e_max_mac_per_vf_set(struct devlink *devlink,
+				   u32 id,
+				   struct devlink_param_gset_ctx *ctx,
+				   struct netlink_ext_ack *extack)
+{
+	struct i40e_pf *pf = devlink_priv(devlink);
+
+	pf->max_mac_per_vf = ctx->val.vu32;
+	return 0;
+}
+
+static int i40e_max_mac_per_vf_get(struct devlink *devlink,
+				   u32 id,
+				   struct devlink_param_gset_ctx *ctx)
+{
+	struct i40e_pf *pf = devlink_priv(devlink);
+
+	ctx->val.vu32 = pf->max_mac_per_vf;
+	return 0;
+}
+
+enum i40e_dl_param_id {
+	I40E_DEVLINK_PARAM_ID_BASE = DEVLINK_PARAM_GENERIC_ID_MAX,
+	I40E_DEVLINK_PARAM_ID_MAX_MAC_PER_VF,
+};
+
+static const struct devlink_param i40e_dl_params[] = {
+	DEVLINK_PARAM_DRIVER(I40E_DEVLINK_PARAM_ID_MAX_MAC_PER_VF,
+			     "max_mac_per_vf",
+			     DEVLINK_PARAM_TYPE_U32,
+			     BIT(DEVLINK_PARAM_CMODE_RUNTIME),
+			     i40e_max_mac_per_vf_get,
+			     i40e_max_mac_per_vf_set,
+			     NULL),
+};
+
 static void i40e_info_get_dsn(struct i40e_pf *pf, char *buf, size_t len)
 {
 	u8 dsn[8];
@@ -165,7 +201,19 @@ void i40e_free_pf(struct i40e_pf *pf)
  **/
 void i40e_devlink_register(struct i40e_pf *pf)
 {
-	devlink_register(priv_to_devlink(pf));
+	int err;
+	struct devlink *dl = priv_to_devlink(pf);
+	struct device *dev = &pf->pdev->dev;
+
+	err = devlink_params_register(dl, i40e_dl_params,
+				      ARRAY_SIZE(i40e_dl_params));
+	if (err) {
+		dev_err(dev,
+			"devlink params register failed with error %d", err);
+	}
+
+	devlink_register(dl);
+
 }
 
 /**
@@ -176,7 +224,11 @@ void i40e_devlink_register(struct i40e_pf *pf)
  **/
 void i40e_devlink_unregister(struct i40e_pf *pf)
 {
-	devlink_unregister(priv_to_devlink(pf));
+	struct devlink *dl = priv_to_devlink(pf);
+
+	devlink_unregister(dl);
+	devlink_params_unregister(dl, i40e_dl_params,
+				  ARRAY_SIZE(i40e_dl_params));
 }
 
 /**
diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
index 081a4526a2f0..e7c0c791eed1 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
@@ -2935,19 +2935,23 @@ static inline int i40e_check_vf_permission(struct i40e_vf *vf,
 		if (!f)
 			++mac_add_cnt;
 	}
-
-	/* If this VF is not privileged, then we can't add more than a limited
-	 * number of addresses.
+	/* Determine the maximum number of MAC addresses this VF may use.
+	 *
+	 * - For untrusted VFs: use a fixed small limit.
+	 *
+	 * - For trusted VFs: limit is calculated by dividing total MAC
+	 *  filter pool across all VFs/ports.
 	 *
-	 * If this VF is trusted, it can use more resources than untrusted.
-	 * However to ensure that every trusted VF has appropriate number of
-	 * resources, divide whole pool of resources per port and then across
-	 * all VFs.
+	 * - User can override this by devlink param "max_mac_per_vf".
+	 *   If set its value is used as a strict cap.
 	 */
-	if (!vf_trusted)
+	if (!vf_trusted) {
 		mac_add_max = I40E_VC_MAX_MAC_ADDR_PER_VF;
-	else
+	} else {
 		mac_add_max = I40E_VC_MAX_MACVLAN_PER_TRUSTED_VF(pf->num_alloc_vfs, hw->num_ports);
+		if (pf->max_mac_per_vf > 0)
+			mac_add_max = pf->max_mac_per_vf;
+	}
 
 	/* VF can replace all its filters in one step, in this case mac_add_max
 	 * will be added as active and another mac_add_max will be in
@@ -2961,7 +2965,8 @@ static inline int i40e_check_vf_permission(struct i40e_vf *vf,
 			return -EPERM;
 		} else {
 			dev_err(&pf->pdev->dev,
-				"Cannot add more MAC addresses, trusted VF exhausted it's resources\n");
+				"Cannot add more MAC addresses: trusted VF reached its maximum allowed limit (%d)\n",
+				mac_add_max);
 			return -EPERM;
 		}
 	}
-- 
2.47.3

Re: [PATCH net v2] i40e: add devlink param to control VF MAC address limit

[Tony Nguyen]

On 8/23/2025 2:49 AM, mheib@redhat.com wrote:
> From: Mohammad Heib <mheib@redhat.com>
> 
> This patch introduces a new devlink runtime parameter that controls
> the maximum number of MAC filters allowed per VF.
> 
> The parameter is an integer value. If set to a non-zero number, it is
> used as a strict per-VF cap. If left at zero, the driver falls back to
> the default limit calculated from the number of allocated VFs and
> ports.
> 
> This makes the limit policy explicit and configurable by user space,
> instead of being only driver internal logic.
> 
> Example command to enable per-vf mac limit:
>   - devlink dev param set pci/0000:3b:00.0 name max_mac_per_vf \
> 	value 12 \
> 	cmode runtime
> 
> - Previous discussion about this change:
>    https://lore.kernel.org/netdev/20250805134042.2604897-1-dhill@redhat.com
> 
> Fixes: cfb1d572c986 ("i40e: Add ensurance of MacVlan resources for every trusted VF")
> Signed-off-by: Mohammad Heib <mheib@redhat.com>
> Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
> ---
>   Documentation/networking/devlink/i40e.rst     | 22 ++++++++
>   drivers/net/ethernet/intel/i40e/i40e.h        |  4 ++
>   .../net/ethernet/intel/i40e/i40e_devlink.c    | 56 ++++++++++++++++++-
>   .../ethernet/intel/i40e/i40e_virtchnl_pf.c    | 25 +++++----
>   4 files changed, 95 insertions(+), 12 deletions(-)
> 
> diff --git a/Documentation/networking/devlink/i40e.rst b/Documentation/networking/devlink/i40e.rst
> index d3cb5bb5197e..f8d5b00bb51d 100644
> --- a/Documentation/networking/devlink/i40e.rst
> +++ b/Documentation/networking/devlink/i40e.rst
> @@ -7,6 +7,28 @@ i40e devlink support
>   This document describes the devlink features implemented by the ``i40e``
>   device driver.
>   
> +Parameters
> +==========
> +
> +.. list-table:: Driver specific parameters implemented
> +    :widths: 5 5 90
> +
> +    * - Name
> +      - Mode
> +      - Description
> +    * - ``max_mac_per_vf``
> +      - runtime
> +      - Controls the maximum number of MAC addresses a VF can use on i40e devices.

Are you intending for this to be for all VFs or only trusted? The 
changes look to be only for trusted VFs, but it's not clear to me from 
the documentation/comments.

> +        By default (``0``), the driver enforces its internally calculated per-VF
> +        MAC filter limit, which is based on the number of allocated VFS.
> +
> +        If set to a non-zero value, this parameter acts as a strict cap:
> +        the driver enforces the maximum of the user-provided value and ignore
> +        internally calculated limit.

The filters are a shared resource. This will allow over-subscription; 
other VFs could be starved
of filters due to this. Since the user/PF is controlling, this is 
probably ok but should be documented. Also, since these are shared, this 
value acts as a theoretical max value, the hardware will start returning 
errors when its limit are reached.

> +        The default value is ``0``.
> +
>   Info versions
>   =============
>   
> diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
> index 801a57a925da..d2d03db2acec 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e.h
> +++ b/drivers/net/ethernet/intel/i40e/i40e.h
> @@ -574,6 +574,10 @@ struct i40e_pf {
>   	struct i40e_vf *vf;
>   	int num_alloc_vfs;	/* actual number of VFs allocated */
>   	u32 vf_aq_requests;
> +	/* If set to non-zero, the device uses this value
> +	 * as maximum number of MAC filters per VF.
> +	 */
> +	u32 max_mac_per_vf;
>   	u32 arq_overflows;	/* Not fatal, possibly indicative of problems */
>   	struct ratelimit_state mdd_message_rate_limit;
>   	/* DCBx/DCBNL capability for PF that indicates
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_devlink.c b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
> index cc4e9e2addb7..8532e40b5c7d 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_devlink.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
> @@ -5,6 +5,42 @@
>   #include "i40e.h"
>   #include "i40e_devlink.h"
>   
> +static int i40e_max_mac_per_vf_set(struct devlink *devlink,
> +				   u32 id,
> +				   struct devlink_param_gset_ctx *ctx,
> +				   struct netlink_ext_ack *extack)
> +{
> +	struct i40e_pf *pf = devlink_priv(devlink);
> +
> +	pf->max_mac_per_vf = ctx->val.vu32;
> +	return 0;
> +}
> +
> +static int i40e_max_mac_per_vf_get(struct devlink *devlink,
> +				   u32 id,
> +				   struct devlink_param_gset_ctx *ctx)
> +{
> +	struct i40e_pf *pf = devlink_priv(devlink);
> +
> +	ctx->val.vu32 = pf->max_mac_per_vf;
> +	return 0;
> +}
> +
> +enum i40e_dl_param_id {
> +	I40E_DEVLINK_PARAM_ID_BASE = DEVLINK_PARAM_GENERIC_ID_MAX,
> +	I40E_DEVLINK_PARAM_ID_MAX_MAC_PER_VF,
> +};
> +
> +static const struct devlink_param i40e_dl_params[] = {
> +	DEVLINK_PARAM_DRIVER(I40E_DEVLINK_PARAM_ID_MAX_MAC_PER_VF,
> +			     "max_mac_per_vf",
> +			     DEVLINK_PARAM_TYPE_U32,
> +			     BIT(DEVLINK_PARAM_CMODE_RUNTIME),
> +			     i40e_max_mac_per_vf_get,
> +			     i40e_max_mac_per_vf_set,
> +			     NULL),
> +};
> +
>   static void i40e_info_get_dsn(struct i40e_pf *pf, char *buf, size_t len)
>   {
>   	u8 dsn[8];
> @@ -165,7 +201,19 @@ void i40e_free_pf(struct i40e_pf *pf)
>    **/
>   void i40e_devlink_register(struct i40e_pf *pf)
>   {
> -	devlink_register(priv_to_devlink(pf));
> +	int err;

RCT; declarations should order from longest to shortest.

> +	struct devlink *dl = priv_to_devlink(pf);
> +	struct device *dev = &pf->pdev->dev;
> +
> +	err = devlink_params_register(dl, i40e_dl_params,
> +				      ARRAY_SIZE(i40e_dl_params));
> +	if (err) {
> +		dev_err(dev,
> +			"devlink params register failed with error %d", err);
> +	}

Braces not needed here.

Thanks,
Tony

Re: [PATCH net v2] i40e: add devlink param to control VF MAC address limit

[mohammad heib]

Hi Tony,


On 8/28/25 12:14 AM, Tony Nguyen wrote:
>
>
> On 8/23/2025 2:49 AM, mheib@redhat.com wrote:
>> From: Mohammad Heib <mheib@redhat.com>
>>
>> This patch introduces a new devlink runtime parameter that controls
>> the maximum number of MAC filters allowed per VF.
>>
>> The parameter is an integer value. If set to a non-zero number, it is
>> used as a strict per-VF cap. If left at zero, the driver falls back to
>> the default limit calculated from the number of allocated VFs and
>> ports.
>>
>> This makes the limit policy explicit and configurable by user space,
>> instead of being only driver internal logic.
>>
>> Example command to enable per-vf mac limit:
>>   - devlink dev param set pci/0000:3b:00.0 name max_mac_per_vf \
>>     value 12 \
>>     cmode runtime
>>
>> - Previous discussion about this change:
>> https://lore.kernel.org/netdev/20250805134042.2604897-1-dhill@redhat.com
>>
>> Fixes: cfb1d572c986 ("i40e: Add ensurance of MacVlan resources for 
>> every trusted VF")
>> Signed-off-by: Mohammad Heib <mheib@redhat.com>
>> Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
>> ---
>>   Documentation/networking/devlink/i40e.rst     | 22 ++++++++
>>   drivers/net/ethernet/intel/i40e/i40e.h        |  4 ++
>>   .../net/ethernet/intel/i40e/i40e_devlink.c    | 56 ++++++++++++++++++-
>>   .../ethernet/intel/i40e/i40e_virtchnl_pf.c    | 25 +++++----
>>   4 files changed, 95 insertions(+), 12 deletions(-)
>>
>> diff --git a/Documentation/networking/devlink/i40e.rst 
>> b/Documentation/networking/devlink/i40e.rst
>> index d3cb5bb5197e..f8d5b00bb51d 100644
>> --- a/Documentation/networking/devlink/i40e.rst
>> +++ b/Documentation/networking/devlink/i40e.rst
>> @@ -7,6 +7,28 @@ i40e devlink support
>>   This document describes the devlink features implemented by the 
>> ``i40e``
>>   device driver.
>>   +Parameters
>> +==========
>> +
>> +.. list-table:: Driver specific parameters implemented
>> +    :widths: 5 5 90
>> +
>> +    * - Name
>> +      - Mode
>> +      - Description
>> +    * - ``max_mac_per_vf``
>> +      - runtime
>> +      - Controls the maximum number of MAC addresses a VF can use on 
>> i40e devices.
>
> Are you intending for this to be for all VFs or only trusted? The 
> changes look to be only for trusted VFs, but it's not clear to me from 
> the documentation/comments.
>
>> +        By default (``0``), the driver enforces its internally 
>> calculated per-VF
>> +        MAC filter limit, which is based on the number of allocated 
>> VFS.
>> +
>> +        If set to a non-zero value, this parameter acts as a strict 
>> cap:
>> +        the driver enforces the maximum of the user-provided value 
>> and ignore
>> +        internally calculated limit.
>
> The filters are a shared resource. This will allow over-subscription; 
> other VFs could be starved
> of filters due to this. Since the user/PF is controlling, this is 
> probably ok but should be documented. Also, since these are shared, 
> this value acts as a theoretical max value, the hardware will start 
> returning errors when its limit are reached.
>
>> +        The default value is ``0``.
>> +
>>   Info versions
>>   =============
>>   diff --git a/drivers/net/ethernet/intel/i40e/i40e.h 
>> b/drivers/net/ethernet/intel/i40e/i40e.h
>> index 801a57a925da..d2d03db2acec 100644
>> --- a/drivers/net/ethernet/intel/i40e/i40e.h
>> +++ b/drivers/net/ethernet/intel/i40e/i40e.h
>> @@ -574,6 +574,10 @@ struct i40e_pf {
>>       struct i40e_vf *vf;
>>       int num_alloc_vfs;    /* actual number of VFs allocated */
>>       u32 vf_aq_requests;
>> +    /* If set to non-zero, the device uses this value
>> +     * as maximum number of MAC filters per VF.
>> +     */
>> +    u32 max_mac_per_vf;
>>       u32 arq_overflows;    /* Not fatal, possibly indicative of 
>> problems */
>>       struct ratelimit_state mdd_message_rate_limit;
>>       /* DCBx/DCBNL capability for PF that indicates
>> diff --git a/drivers/net/ethernet/intel/i40e/i40e_devlink.c 
>> b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
>> index cc4e9e2addb7..8532e40b5c7d 100644
>> --- a/drivers/net/ethernet/intel/i40e/i40e_devlink.c
>> +++ b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
>> @@ -5,6 +5,42 @@
>>   #include "i40e.h"
>>   #include "i40e_devlink.h"
>>   +static int i40e_max_mac_per_vf_set(struct devlink *devlink,
>> +                   u32 id,
>> +                   struct devlink_param_gset_ctx *ctx,
>> +                   struct netlink_ext_ack *extack)
>> +{
>> +    struct i40e_pf *pf = devlink_priv(devlink);
>> +
>> +    pf->max_mac_per_vf = ctx->val.vu32;
>> +    return 0;
>> +}
>> +
>> +static int i40e_max_mac_per_vf_get(struct devlink *devlink,
>> +                   u32 id,
>> +                   struct devlink_param_gset_ctx *ctx)
>> +{
>> +    struct i40e_pf *pf = devlink_priv(devlink);
>> +
>> +    ctx->val.vu32 = pf->max_mac_per_vf;
>> +    return 0;
>> +}
>> +
>> +enum i40e_dl_param_id {
>> +    I40E_DEVLINK_PARAM_ID_BASE = DEVLINK_PARAM_GENERIC_ID_MAX,
>> +    I40E_DEVLINK_PARAM_ID_MAX_MAC_PER_VF,
>> +};
>> +
>> +static const struct devlink_param i40e_dl_params[] = {
>> +    DEVLINK_PARAM_DRIVER(I40E_DEVLINK_PARAM_ID_MAX_MAC_PER_VF,
>> +                 "max_mac_per_vf",
>> +                 DEVLINK_PARAM_TYPE_U32,
>> +                 BIT(DEVLINK_PARAM_CMODE_RUNTIME),
>> +                 i40e_max_mac_per_vf_get,
>> +                 i40e_max_mac_per_vf_set,
>> +                 NULL),
>> +};
>> +
>>   static void i40e_info_get_dsn(struct i40e_pf *pf, char *buf, size_t 
>> len)
>>   {
>>       u8 dsn[8];
>> @@ -165,7 +201,19 @@ void i40e_free_pf(struct i40e_pf *pf)
>>    **/
>>   void i40e_devlink_register(struct i40e_pf *pf)
>>   {
>> -    devlink_register(priv_to_devlink(pf));
>> +    int err;
>
> RCT; declarations should order from longest to shortest.
>
>> +    struct devlink *dl = priv_to_devlink(pf);
>> +    struct device *dev = &pf->pdev->dev;
>> +
>> +    err = devlink_params_register(dl, i40e_dl_params,
>> +                      ARRAY_SIZE(i40e_dl_params));
>> +    if (err) {
>> +        dev_err(dev,
>> +            "devlink params register failed with error %d", err);
>> +    }
>
> Braces not needed here.
>
> Thanks,
> Tony
>

Thank you for your review.
yes agree this need to be more documented i updated the devlink param 
documentation to include your comment.
and fixed the minor code issue all in v3.
thanks.

Re: [PATCH net v2] i40e: add devlink param to control VF MAC address limit

[Jiri Pirko]

Sat, Aug 23, 2025 at 11:49:52AM +0200, mheib@redhat.com wrote:
>From: Mohammad Heib <mheib@redhat.com>
>
>This patch introduces a new devlink runtime parameter that controls
>the maximum number of MAC filters allowed per VF.
>
>The parameter is an integer value. If set to a non-zero number, it is
>used as a strict per-VF cap. If left at zero, the driver falls back to
>the default limit calculated from the number of allocated VFs and
>ports.
>
>This makes the limit policy explicit and configurable by user space,
>instead of being only driver internal logic.
>
>Example command to enable per-vf mac limit:
> - devlink dev param set pci/0000:3b:00.0 name max_mac_per_vf \
>	value 12 \
>	cmode runtime
>
>- Previous discussion about this change:
>  https://lore.kernel.org/netdev/20250805134042.2604897-1-dhill@redhat.com
>
>Fixes: cfb1d572c986 ("i40e: Add ensurance of MacVlan resources for every trusted VF")
>Signed-off-by: Mohammad Heib <mheib@redhat.com>
>Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
>---
> Documentation/networking/devlink/i40e.rst     | 22 ++++++++
> drivers/net/ethernet/intel/i40e/i40e.h        |  4 ++
> .../net/ethernet/intel/i40e/i40e_devlink.c    | 56 ++++++++++++++++++-
> .../ethernet/intel/i40e/i40e_virtchnl_pf.c    | 25 +++++----
> 4 files changed, 95 insertions(+), 12 deletions(-)
>
>diff --git a/Documentation/networking/devlink/i40e.rst b/Documentation/networking/devlink/i40e.rst
>index d3cb5bb5197e..f8d5b00bb51d 100644
>--- a/Documentation/networking/devlink/i40e.rst
>+++ b/Documentation/networking/devlink/i40e.rst
>@@ -7,6 +7,28 @@ i40e devlink support
> This document describes the devlink features implemented by the ``i40e``
> device driver.
> 
>+Parameters
>+==========
>+
>+.. list-table:: Driver specific parameters implemented
>+    :widths: 5 5 90
>+
>+    * - Name
>+      - Mode
>+      - Description
>+    * - ``max_mac_per_vf``
>+      - runtime
>+      - Controls the maximum number of MAC addresses a VF can use on i40e devices.
>+
>+        By default (``0``), the driver enforces its internally calculated per-VF
>+        MAC filter limit, which is based on the number of allocated VFS.
>+
>+        If set to a non-zero value, this parameter acts as a strict cap:
>+        the driver enforces the maximum of the user-provided value and ignore
>+        internally calculated limit.
>+
>+        The default value is ``0``.
>+
> Info versions
> =============
> 
>diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
>index 801a57a925da..d2d03db2acec 100644
>--- a/drivers/net/ethernet/intel/i40e/i40e.h
>+++ b/drivers/net/ethernet/intel/i40e/i40e.h
>@@ -574,6 +574,10 @@ struct i40e_pf {
> 	struct i40e_vf *vf;
> 	int num_alloc_vfs;	/* actual number of VFs allocated */
> 	u32 vf_aq_requests;
>+	/* If set to non-zero, the device uses this value
>+	 * as maximum number of MAC filters per VF.
>+	 */
>+	u32 max_mac_per_vf;
> 	u32 arq_overflows;	/* Not fatal, possibly indicative of problems */
> 	struct ratelimit_state mdd_message_rate_limit;
> 	/* DCBx/DCBNL capability for PF that indicates
>diff --git a/drivers/net/ethernet/intel/i40e/i40e_devlink.c b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
>index cc4e9e2addb7..8532e40b5c7d 100644
>--- a/drivers/net/ethernet/intel/i40e/i40e_devlink.c
>+++ b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
>@@ -5,6 +5,42 @@
> #include "i40e.h"
> #include "i40e_devlink.h"
> 
>+static int i40e_max_mac_per_vf_set(struct devlink *devlink,
>+				   u32 id,
>+				   struct devlink_param_gset_ctx *ctx,
>+				   struct netlink_ext_ack *extack)
>+{
>+	struct i40e_pf *pf = devlink_priv(devlink);
>+
>+	pf->max_mac_per_vf = ctx->val.vu32;
>+	return 0;
>+}
>+
>+static int i40e_max_mac_per_vf_get(struct devlink *devlink,
>+				   u32 id,
>+				   struct devlink_param_gset_ctx *ctx)
>+{
>+	struct i40e_pf *pf = devlink_priv(devlink);
>+
>+	ctx->val.vu32 = pf->max_mac_per_vf;
>+	return 0;
>+}
>+
>+enum i40e_dl_param_id {
>+	I40E_DEVLINK_PARAM_ID_BASE = DEVLINK_PARAM_GENERIC_ID_MAX,
>+	I40E_DEVLINK_PARAM_ID_MAX_MAC_PER_VF,

What's so i40 specific about this? Sounds pretty generic to be.



>+};
>+
>+static const struct devlink_param i40e_dl_params[] = {
>+	DEVLINK_PARAM_DRIVER(I40E_DEVLINK_PARAM_ID_MAX_MAC_PER_VF,
>+			     "max_mac_per_vf",
>+			     DEVLINK_PARAM_TYPE_U32,
>+			     BIT(DEVLINK_PARAM_CMODE_RUNTIME),
>+			     i40e_max_mac_per_vf_get,
>+			     i40e_max_mac_per_vf_set,
>+			     NULL),
>+};
>+
> static void i40e_info_get_dsn(struct i40e_pf *pf, char *buf, size_t len)
> {
> 	u8 dsn[8];
>@@ -165,7 +201,19 @@ void i40e_free_pf(struct i40e_pf *pf)
>  **/
> void i40e_devlink_register(struct i40e_pf *pf)
> {
>-	devlink_register(priv_to_devlink(pf));
>+	int err;
>+	struct devlink *dl = priv_to_devlink(pf);
>+	struct device *dev = &pf->pdev->dev;
>+
>+	err = devlink_params_register(dl, i40e_dl_params,
>+				      ARRAY_SIZE(i40e_dl_params));
>+	if (err) {
>+		dev_err(dev,
>+			"devlink params register failed with error %d", err);
>+	}
>+
>+	devlink_register(dl);
>+
> }
> 
> /**
>@@ -176,7 +224,11 @@ void i40e_devlink_register(struct i40e_pf *pf)
>  **/
> void i40e_devlink_unregister(struct i40e_pf *pf)
> {
>-	devlink_unregister(priv_to_devlink(pf));
>+	struct devlink *dl = priv_to_devlink(pf);
>+
>+	devlink_unregister(dl);
>+	devlink_params_unregister(dl, i40e_dl_params,
>+				  ARRAY_SIZE(i40e_dl_params));
> }
> 
> /**
>diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>index 081a4526a2f0..e7c0c791eed1 100644
>--- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>+++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>@@ -2935,19 +2935,23 @@ static inline int i40e_check_vf_permission(struct i40e_vf *vf,
> 		if (!f)
> 			++mac_add_cnt;
> 	}
>-
>-	/* If this VF is not privileged, then we can't add more than a limited
>-	 * number of addresses.
>+	/* Determine the maximum number of MAC addresses this VF may use.
>+	 *
>+	 * - For untrusted VFs: use a fixed small limit.
>+	 *
>+	 * - For trusted VFs: limit is calculated by dividing total MAC
>+	 *  filter pool across all VFs/ports.
> 	 *
>-	 * If this VF is trusted, it can use more resources than untrusted.
>-	 * However to ensure that every trusted VF has appropriate number of
>-	 * resources, divide whole pool of resources per port and then across
>-	 * all VFs.
>+	 * - User can override this by devlink param "max_mac_per_vf".
>+	 *   If set its value is used as a strict cap.
> 	 */
>-	if (!vf_trusted)
>+	if (!vf_trusted) {
> 		mac_add_max = I40E_VC_MAX_MAC_ADDR_PER_VF;
>-	else
>+	} else {
> 		mac_add_max = I40E_VC_MAX_MACVLAN_PER_TRUSTED_VF(pf->num_alloc_vfs, hw->num_ports);
>+		if (pf->max_mac_per_vf > 0)
>+			mac_add_max = pf->max_mac_per_vf;
>+	}
> 
> 	/* VF can replace all its filters in one step, in this case mac_add_max
> 	 * will be added as active and another mac_add_max will be in
>@@ -2961,7 +2965,8 @@ static inline int i40e_check_vf_permission(struct i40e_vf *vf,
> 			return -EPERM;
> 		} else {
> 			dev_err(&pf->pdev->dev,
>-				"Cannot add more MAC addresses, trusted VF exhausted it's resources\n");
>+				"Cannot add more MAC addresses: trusted VF reached its maximum allowed limit (%d)\n",
>+				mac_add_max);
> 			return -EPERM;
> 		}
> 	}
>-- 
>2.47.3
>

Re: [PATCH net v2] i40e: add devlink param to control VF MAC address limit

[mohammad heib]

Hi Jiri

On 8/28/25 2:43 PM, Jiri Pirko wrote:
> Sat, Aug 23, 2025 at 11:49:52AM +0200, mheib@redhat.com wrote:
>> From: Mohammad Heib <mheib@redhat.com>
>>
>> This patch introduces a new devlink runtime parameter that controls
>> the maximum number of MAC filters allowed per VF.
>>
>> The parameter is an integer value. If set to a non-zero number, it is
>> used as a strict per-VF cap. If left at zero, the driver falls back to
>> the default limit calculated from the number of allocated VFs and
>> ports.
>>
>> This makes the limit policy explicit and configurable by user space,
>> instead of being only driver internal logic.
>>
>> Example command to enable per-vf mac limit:
>> - devlink dev param set pci/0000:3b:00.0 name max_mac_per_vf \
>> 	value 12 \
>> 	cmode runtime
>>
>> - Previous discussion about this change:
>>   https://lore.kernel.org/netdev/20250805134042.2604897-1-dhill@redhat.com
>>
>> Fixes: cfb1d572c986 ("i40e: Add ensurance of MacVlan resources for every trusted VF")
>> Signed-off-by: Mohammad Heib <mheib@redhat.com>
>> Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
>> ---
>> Documentation/networking/devlink/i40e.rst     | 22 ++++++++
>> drivers/net/ethernet/intel/i40e/i40e.h        |  4 ++
>> .../net/ethernet/intel/i40e/i40e_devlink.c    | 56 ++++++++++++++++++-
>> .../ethernet/intel/i40e/i40e_virtchnl_pf.c    | 25 +++++----
>> 4 files changed, 95 insertions(+), 12 deletions(-)
>>
>> diff --git a/Documentation/networking/devlink/i40e.rst b/Documentation/networking/devlink/i40e.rst
>> index d3cb5bb5197e..f8d5b00bb51d 100644
>> --- a/Documentation/networking/devlink/i40e.rst
>> +++ b/Documentation/networking/devlink/i40e.rst
>> @@ -7,6 +7,28 @@ i40e devlink support
>> This document describes the devlink features implemented by the ``i40e``
>> device driver.
>>
>> +Parameters
>> +==========
>> +
>> +.. list-table:: Driver specific parameters implemented
>> +    :widths: 5 5 90
>> +
>> +    * - Name
>> +      - Mode
>> +      - Description
>> +    * - ``max_mac_per_vf``
>> +      - runtime
>> +      - Controls the maximum number of MAC addresses a VF can use on i40e devices.
>> +
>> +        By default (``0``), the driver enforces its internally calculated per-VF
>> +        MAC filter limit, which is based on the number of allocated VFS.
>> +
>> +        If set to a non-zero value, this parameter acts as a strict cap:
>> +        the driver enforces the maximum of the user-provided value and ignore
>> +        internally calculated limit.
>> +
>> +        The default value is ``0``.
>> +
>> Info versions
>> =============
>>
>> diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
>> index 801a57a925da..d2d03db2acec 100644
>> --- a/drivers/net/ethernet/intel/i40e/i40e.h
>> +++ b/drivers/net/ethernet/intel/i40e/i40e.h
>> @@ -574,6 +574,10 @@ struct i40e_pf {
>> 	struct i40e_vf *vf;
>> 	int num_alloc_vfs;	/* actual number of VFs allocated */
>> 	u32 vf_aq_requests;
>> +	/* If set to non-zero, the device uses this value
>> +	 * as maximum number of MAC filters per VF.
>> +	 */
>> +	u32 max_mac_per_vf;
>> 	u32 arq_overflows;	/* Not fatal, possibly indicative of problems */
>> 	struct ratelimit_state mdd_message_rate_limit;
>> 	/* DCBx/DCBNL capability for PF that indicates
>> diff --git a/drivers/net/ethernet/intel/i40e/i40e_devlink.c b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
>> index cc4e9e2addb7..8532e40b5c7d 100644
>> --- a/drivers/net/ethernet/intel/i40e/i40e_devlink.c
>> +++ b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
>> @@ -5,6 +5,42 @@
>> #include "i40e.h"
>> #include "i40e_devlink.h"
>>
>> +static int i40e_max_mac_per_vf_set(struct devlink *devlink,
>> +				   u32 id,
>> +				   struct devlink_param_gset_ctx *ctx,
>> +				   struct netlink_ext_ack *extack)
>> +{
>> +	struct i40e_pf *pf = devlink_priv(devlink);
>> +
>> +	pf->max_mac_per_vf = ctx->val.vu32;
>> +	return 0;
>> +}
>> +
>> +static int i40e_max_mac_per_vf_get(struct devlink *devlink,
>> +				   u32 id,
>> +				   struct devlink_param_gset_ctx *ctx)
>> +{
>> +	struct i40e_pf *pf = devlink_priv(devlink);
>> +
>> +	ctx->val.vu32 = pf->max_mac_per_vf;
>> +	return 0;
>> +}
>> +
>> +enum i40e_dl_param_id {
>> +	I40E_DEVLINK_PARAM_ID_BASE = DEVLINK_PARAM_GENERIC_ID_MAX,
>> +	I40E_DEVLINK_PARAM_ID_MAX_MAC_PER_VF,
> What's so i40 specific about this? Sounds pretty generic to be.
>
>
>
>> +};
>> +
>> +static const struct devlink_param i40e_dl_params[] = {
>> +	DEVLINK_PARAM_DRIVER(I40E_DEVLINK_PARAM_ID_MAX_MAC_PER_VF,
>> +			     "max_mac_per_vf",
>> +			     DEVLINK_PARAM_TYPE_U32,
>> +			     BIT(DEVLINK_PARAM_CMODE_RUNTIME),
>> +			     i40e_max_mac_per_vf_get,
>> +			     i40e_max_mac_per_vf_set,
>> +			     NULL),
>> +};
>> +
>> static void i40e_info_get_dsn(struct i40e_pf *pf, char *buf, size_t len)
>> {
>> 	u8 dsn[8];
>> @@ -165,7 +201,19 @@ void i40e_free_pf(struct i40e_pf *pf)
>>   **/
>> void i40e_devlink_register(struct i40e_pf *pf)
>> {
>> -	devlink_register(priv_to_devlink(pf));
>> +	int err;
>> +	struct devlink *dl = priv_to_devlink(pf);
>> +	struct device *dev = &pf->pdev->dev;
>> +
>> +	err = devlink_params_register(dl, i40e_dl_params,
>> +				      ARRAY_SIZE(i40e_dl_params));
>> +	if (err) {
>> +		dev_err(dev,
>> +			"devlink params register failed with error %d", err);
>> +	}
>> +
>> +	devlink_register(dl);
>> +
>> }
>>
>> /**
>> @@ -176,7 +224,11 @@ void i40e_devlink_register(struct i40e_pf *pf)
>>   **/
>> void i40e_devlink_unregister(struct i40e_pf *pf)
>> {
>> -	devlink_unregister(priv_to_devlink(pf));
>> +	struct devlink *dl = priv_to_devlink(pf);
>> +
>> +	devlink_unregister(dl);
>> +	devlink_params_unregister(dl, i40e_dl_params,
>> +				  ARRAY_SIZE(i40e_dl_params));
>> }
>>
>> /**
>> diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> index 081a4526a2f0..e7c0c791eed1 100644
>> --- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> +++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> @@ -2935,19 +2935,23 @@ static inline int i40e_check_vf_permission(struct i40e_vf *vf,
>> 		if (!f)
>> 			++mac_add_cnt;
>> 	}
>> -
>> -	/* If this VF is not privileged, then we can't add more than a limited
>> -	 * number of addresses.
>> +	/* Determine the maximum number of MAC addresses this VF may use.
>> +	 *
>> +	 * - For untrusted VFs: use a fixed small limit.
>> +	 *
>> +	 * - For trusted VFs: limit is calculated by dividing total MAC
>> +	 *  filter pool across all VFs/ports.
>> 	 *
>> -	 * If this VF is trusted, it can use more resources than untrusted.
>> -	 * However to ensure that every trusted VF has appropriate number of
>> -	 * resources, divide whole pool of resources per port and then across
>> -	 * all VFs.
>> +	 * - User can override this by devlink param "max_mac_per_vf".
>> +	 *   If set its value is used as a strict cap.
>> 	 */
>> -	if (!vf_trusted)
>> +	if (!vf_trusted) {
>> 		mac_add_max = I40E_VC_MAX_MAC_ADDR_PER_VF;
>> -	else
>> +	} else {
>> 		mac_add_max = I40E_VC_MAX_MACVLAN_PER_TRUSTED_VF(pf->num_alloc_vfs, hw->num_ports);
>> +		if (pf->max_mac_per_vf > 0)
>> +			mac_add_max = pf->max_mac_per_vf;
>> +	}
>>
>> 	/* VF can replace all its filters in one step, in this case mac_add_max
>> 	 * will be added as active and another mac_add_max will be in
>> @@ -2961,7 +2965,8 @@ static inline int i40e_check_vf_permission(struct i40e_vf *vf,
>> 			return -EPERM;
>> 		} else {
>> 			dev_err(&pf->pdev->dev,
>> -				"Cannot add more MAC addresses, trusted VF exhausted it's resources\n");
>> +				"Cannot add more MAC addresses: trusted VF reached its maximum allowed limit (%d)\n",
>> +				mac_add_max);
>> 			return -EPERM;
>> 		}
>> 	}
>> -- 
>> 2.47.3
>>
If i understand correctly, you’re asking whether this parameter could be 
added as a generic devlink parameter
rather than a driver-specific one?


if that the case, Yes, it could be made generic, but I initially 
implemented it as driver specific because I was targeting i40e only,
and I thought a generic approach might not be acceptable at this stage


I do plan to extend this to other drivers, as mentioned in the v1 patch 
here:
  - 
https://patchwork.ozlabs.org/project/intel-wired-lan/patch/20250821233930.127420-1-mheib@redhat.com/
For now, i'm pushing hard to get this patch into i40e since it affects a 
customer. Once it's accepted i can extend it
to other drivers and convert it to the generic devlink parameter.


Thanks,

Re: [PATCH net v2] i40e: add devlink param to control VF MAC address limit

[Jiri Pirko]

Thu, Aug 28, 2025 at 02:49:26PM +0200, mheib@redhat.com wrote:
>Hi Jiri
>
>On 8/28/25 2:43 PM, Jiri Pirko wrote:
>> Sat, Aug 23, 2025 at 11:49:52AM +0200, mheib@redhat.com wrote:
>> > From: Mohammad Heib <mheib@redhat.com>
>> > 
>> > This patch introduces a new devlink runtime parameter that controls
>> > the maximum number of MAC filters allowed per VF.
>> > 
>> > The parameter is an integer value. If set to a non-zero number, it is
>> > used as a strict per-VF cap. If left at zero, the driver falls back to
>> > the default limit calculated from the number of allocated VFs and
>> > ports.
>> > 
>> > This makes the limit policy explicit and configurable by user space,
>> > instead of being only driver internal logic.
>> > 
>> > Example command to enable per-vf mac limit:
>> > - devlink dev param set pci/0000:3b:00.0 name max_mac_per_vf \
>> > 	value 12 \
>> > 	cmode runtime
>> > 
>> > - Previous discussion about this change:
>> >   https://lore.kernel.org/netdev/20250805134042.2604897-1-dhill@redhat.com
>> > 
>> > Fixes: cfb1d572c986 ("i40e: Add ensurance of MacVlan resources for every trusted VF")
>> > Signed-off-by: Mohammad Heib <mheib@redhat.com>
>> > Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
>> > ---
>> > Documentation/networking/devlink/i40e.rst     | 22 ++++++++
>> > drivers/net/ethernet/intel/i40e/i40e.h        |  4 ++
>> > .../net/ethernet/intel/i40e/i40e_devlink.c    | 56 ++++++++++++++++++-
>> > .../ethernet/intel/i40e/i40e_virtchnl_pf.c    | 25 +++++----
>> > 4 files changed, 95 insertions(+), 12 deletions(-)
>> > 
>> > diff --git a/Documentation/networking/devlink/i40e.rst b/Documentation/networking/devlink/i40e.rst
>> > index d3cb5bb5197e..f8d5b00bb51d 100644
>> > --- a/Documentation/networking/devlink/i40e.rst
>> > +++ b/Documentation/networking/devlink/i40e.rst
>> > @@ -7,6 +7,28 @@ i40e devlink support
>> > This document describes the devlink features implemented by the ``i40e``
>> > device driver.
>> > 
>> > +Parameters
>> > +==========
>> > +
>> > +.. list-table:: Driver specific parameters implemented
>> > +    :widths: 5 5 90
>> > +
>> > +    * - Name
>> > +      - Mode
>> > +      - Description
>> > +    * - ``max_mac_per_vf``
>> > +      - runtime
>> > +      - Controls the maximum number of MAC addresses a VF can use on i40e devices.
>> > +
>> > +        By default (``0``), the driver enforces its internally calculated per-VF
>> > +        MAC filter limit, which is based on the number of allocated VFS.
>> > +
>> > +        If set to a non-zero value, this parameter acts as a strict cap:
>> > +        the driver enforces the maximum of the user-provided value and ignore
>> > +        internally calculated limit.
>> > +
>> > +        The default value is ``0``.
>> > +
>> > Info versions
>> > =============
>> > 
>> > diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
>> > index 801a57a925da..d2d03db2acec 100644
>> > --- a/drivers/net/ethernet/intel/i40e/i40e.h
>> > +++ b/drivers/net/ethernet/intel/i40e/i40e.h
>> > @@ -574,6 +574,10 @@ struct i40e_pf {
>> > 	struct i40e_vf *vf;
>> > 	int num_alloc_vfs;	/* actual number of VFs allocated */
>> > 	u32 vf_aq_requests;
>> > +	/* If set to non-zero, the device uses this value
>> > +	 * as maximum number of MAC filters per VF.
>> > +	 */
>> > +	u32 max_mac_per_vf;
>> > 	u32 arq_overflows;	/* Not fatal, possibly indicative of problems */
>> > 	struct ratelimit_state mdd_message_rate_limit;
>> > 	/* DCBx/DCBNL capability for PF that indicates
>> > diff --git a/drivers/net/ethernet/intel/i40e/i40e_devlink.c b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
>> > index cc4e9e2addb7..8532e40b5c7d 100644
>> > --- a/drivers/net/ethernet/intel/i40e/i40e_devlink.c
>> > +++ b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
>> > @@ -5,6 +5,42 @@
>> > #include "i40e.h"
>> > #include "i40e_devlink.h"
>> > 
>> > +static int i40e_max_mac_per_vf_set(struct devlink *devlink,
>> > +				   u32 id,
>> > +				   struct devlink_param_gset_ctx *ctx,
>> > +				   struct netlink_ext_ack *extack)
>> > +{
>> > +	struct i40e_pf *pf = devlink_priv(devlink);
>> > +
>> > +	pf->max_mac_per_vf = ctx->val.vu32;
>> > +	return 0;
>> > +}
>> > +
>> > +static int i40e_max_mac_per_vf_get(struct devlink *devlink,
>> > +				   u32 id,
>> > +				   struct devlink_param_gset_ctx *ctx)
>> > +{
>> > +	struct i40e_pf *pf = devlink_priv(devlink);
>> > +
>> > +	ctx->val.vu32 = pf->max_mac_per_vf;
>> > +	return 0;
>> > +}
>> > +
>> > +enum i40e_dl_param_id {
>> > +	I40E_DEVLINK_PARAM_ID_BASE = DEVLINK_PARAM_GENERIC_ID_MAX,
>> > +	I40E_DEVLINK_PARAM_ID_MAX_MAC_PER_VF,
>> What's so i40 specific about this? Sounds pretty generic to be.
>> 
>> 
>> 
>> > +};
>> > +
>> > +static const struct devlink_param i40e_dl_params[] = {
>> > +	DEVLINK_PARAM_DRIVER(I40E_DEVLINK_PARAM_ID_MAX_MAC_PER_VF,
>> > +			     "max_mac_per_vf",
>> > +			     DEVLINK_PARAM_TYPE_U32,
>> > +			     BIT(DEVLINK_PARAM_CMODE_RUNTIME),
>> > +			     i40e_max_mac_per_vf_get,
>> > +			     i40e_max_mac_per_vf_set,
>> > +			     NULL),
>> > +};
>> > +
>> > static void i40e_info_get_dsn(struct i40e_pf *pf, char *buf, size_t len)
>> > {
>> > 	u8 dsn[8];
>> > @@ -165,7 +201,19 @@ void i40e_free_pf(struct i40e_pf *pf)
>> >   **/
>> > void i40e_devlink_register(struct i40e_pf *pf)
>> > {
>> > -	devlink_register(priv_to_devlink(pf));
>> > +	int err;
>> > +	struct devlink *dl = priv_to_devlink(pf);
>> > +	struct device *dev = &pf->pdev->dev;
>> > +
>> > +	err = devlink_params_register(dl, i40e_dl_params,
>> > +				      ARRAY_SIZE(i40e_dl_params));
>> > +	if (err) {
>> > +		dev_err(dev,
>> > +			"devlink params register failed with error %d", err);
>> > +	}
>> > +
>> > +	devlink_register(dl);
>> > +
>> > }
>> > 
>> > /**
>> > @@ -176,7 +224,11 @@ void i40e_devlink_register(struct i40e_pf *pf)
>> >   **/
>> > void i40e_devlink_unregister(struct i40e_pf *pf)
>> > {
>> > -	devlink_unregister(priv_to_devlink(pf));
>> > +	struct devlink *dl = priv_to_devlink(pf);
>> > +
>> > +	devlink_unregister(dl);
>> > +	devlink_params_unregister(dl, i40e_dl_params,
>> > +				  ARRAY_SIZE(i40e_dl_params));
>> > }
>> > 
>> > /**
>> > diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> > index 081a4526a2f0..e7c0c791eed1 100644
>> > --- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> > +++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> > @@ -2935,19 +2935,23 @@ static inline int i40e_check_vf_permission(struct i40e_vf *vf,
>> > 		if (!f)
>> > 			++mac_add_cnt;
>> > 	}
>> > -
>> > -	/* If this VF is not privileged, then we can't add more than a limited
>> > -	 * number of addresses.
>> > +	/* Determine the maximum number of MAC addresses this VF may use.
>> > +	 *
>> > +	 * - For untrusted VFs: use a fixed small limit.
>> > +	 *
>> > +	 * - For trusted VFs: limit is calculated by dividing total MAC
>> > +	 *  filter pool across all VFs/ports.
>> > 	 *
>> > -	 * If this VF is trusted, it can use more resources than untrusted.
>> > -	 * However to ensure that every trusted VF has appropriate number of
>> > -	 * resources, divide whole pool of resources per port and then across
>> > -	 * all VFs.
>> > +	 * - User can override this by devlink param "max_mac_per_vf".
>> > +	 *   If set its value is used as a strict cap.
>> > 	 */
>> > -	if (!vf_trusted)
>> > +	if (!vf_trusted) {
>> > 		mac_add_max = I40E_VC_MAX_MAC_ADDR_PER_VF;
>> > -	else
>> > +	} else {
>> > 		mac_add_max = I40E_VC_MAX_MACVLAN_PER_TRUSTED_VF(pf->num_alloc_vfs, hw->num_ports);
>> > +		if (pf->max_mac_per_vf > 0)
>> > +			mac_add_max = pf->max_mac_per_vf;
>> > +	}
>> > 
>> > 	/* VF can replace all its filters in one step, in this case mac_add_max
>> > 	 * will be added as active and another mac_add_max will be in
>> > @@ -2961,7 +2965,8 @@ static inline int i40e_check_vf_permission(struct i40e_vf *vf,
>> > 			return -EPERM;
>> > 		} else {
>> > 			dev_err(&pf->pdev->dev,
>> > -				"Cannot add more MAC addresses, trusted VF exhausted it's resources\n");
>> > +				"Cannot add more MAC addresses: trusted VF reached its maximum allowed limit (%d)\n",
>> > +				mac_add_max);
>> > 			return -EPERM;
>> > 		}
>> > 	}
>> > -- 
>> > 2.47.3
>> > 
>If i understand correctly, you’re asking whether this parameter could be
>added as a generic devlink parameter
>rather than a driver-specific one?
>
>
>if that the case, Yes, it could be made generic, but I initially implemented
>it as driver specific because I was targeting i40e only,
>and I thought a generic approach might not be acceptable at this stage
>
>
>I do plan to extend this to other drivers, as mentioned in the v1 patch here:
> - https://patchwork.ozlabs.org/project/intel-wired-lan/patch/20250821233930.127420-1-mheib@redhat.com/
>For now, i'm pushing hard to get this patch into i40e since it affects a
>customer. Once it's accepted i can extend it
>to other drivers and convert it to the generic devlink parameter.

No, please do it as generic from start. Thanks!

>
>
>Thanks,
>