[Intel-wired-lan] [PATCH iwl-net] idpf: cap maximum Rx buffer size

[Intel-wired-lan] [PATCH iwl-net] idpf: cap maximum Rx buffer size

[Joshua Hay]

The HW only supports a maximum Rx buffer size of 16K-128. On systems
using large pages, the libeth logic can configure the buffer size to be
larger than this. The upper bound is PAGE_SIZE while the lower bound is
MTU rounded up to the nearest power of 2. For example, ARM systems with
a 64K page size and an mtu of 9000 will set the Rx buffer size to 16K,
which will cause the config Rx queues message to fail.

Initialize the bufq/fill queue buf_len field to the maximum supported
size. This will trigger the libeth logic to cap the maximum Rx buffer
size by reducing the upper bound.

Fixes: 74d1412ac8f37 ("idpf: use libeth Rx buffer management for payload buffer")
Signed-off-by: Joshua Hay <joshua.a.hay@intel.com>
Acked-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Reviewed-by: Madhu Chittim <madhu.chittim@intel.com>
---
 drivers/net/ethernet/intel/idpf/idpf_txrx.c | 8 +++++---
 drivers/net/ethernet/intel/idpf/idpf_txrx.h | 1 +
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
index 828f7c444d30..dcdd4fef1c7a 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
@@ -695,9 +695,10 @@ static int idpf_rx_buf_alloc_singleq(struct idpf_rx_queue *rxq)
 static int idpf_rx_bufs_init_singleq(struct idpf_rx_queue *rxq)
 {
 	struct libeth_fq fq = {
-		.count	= rxq->desc_count,
-		.type	= LIBETH_FQE_MTU,
-		.nid	= idpf_q_vector_to_mem(rxq->q_vector),
+		.count		= rxq->desc_count,
+		.type		= LIBETH_FQE_MTU,
+		.buf_len	= IDPF_RX_MAX_BUF_SZ,
+		.nid		= idpf_q_vector_to_mem(rxq->q_vector),
 	};
 	int ret;
 
@@ -754,6 +755,7 @@ static int idpf_rx_bufs_init(struct idpf_buf_queue *bufq,
 		.truesize	= bufq->truesize,
 		.count		= bufq->desc_count,
 		.type		= type,
+		.buf_len	= IDPF_RX_MAX_BUF_SZ,
 		.hsplit		= idpf_queue_has(HSPLIT_EN, bufq),
 		.xdp		= idpf_xdp_enabled(bufq->q_vector->vport),
 		.nid		= idpf_q_vector_to_mem(bufq->q_vector),
diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.h b/drivers/net/ethernet/intel/idpf/idpf_txrx.h
index 75b977094741..a1255099656f 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_txrx.h
+++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.h
@@ -101,6 +101,7 @@ do {								\
 		idx = 0;					\
 } while (0)
 
+#define IDPF_RX_MAX_BUF_SZ			(16384 - 128)
 #define IDPF_RX_BUF_STRIDE			32
 #define IDPF_RX_BUF_POST_STRIDE			16
 #define IDPF_LOW_WATERMARK			64
-- 
2.39.2

Re: [Intel-wired-lan] [PATCH iwl-net] idpf: cap maximum Rx buffer size

[Jacob Keller]

[-- Attachment #1.1: Type: text/plain, Size: 2756 bytes --]



On 11/3/2025 1:20 PM, Joshua Hay wrote:
> The HW only supports a maximum Rx buffer size of 16K-128. On systems
> using large pages, the libeth logic can configure the buffer size to be
> larger than this. The upper bound is PAGE_SIZE while the lower bound is
> MTU rounded up to the nearest power of 2. For example, ARM systems with
> a 64K page size and an mtu of 9000 will set the Rx buffer size to 16K,
> which will cause the config Rx queues message to fail.
> 
> Initialize the bufq/fill queue buf_len field to the maximum supported
> size. This will trigger the libeth logic to cap the maximum Rx buffer
> size by reducing the upper bound.
> 
> Fixes: 74d1412ac8f37 ("idpf: use libeth Rx buffer management for payload buffer")
> Signed-off-by: Joshua Hay <joshua.a.hay@intel.com>
> Acked-by: Alexander Lobakin <aleksander.lobakin@intel.com>
> Reviewed-by: Madhu Chittim <madhu.chittim@intel.com>
> ---

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>

>  drivers/net/ethernet/intel/idpf/idpf_txrx.c | 8 +++++---
>  drivers/net/ethernet/intel/idpf/idpf_txrx.h | 1 +
>  2 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> index 828f7c444d30..dcdd4fef1c7a 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> @@ -695,9 +695,10 @@ static int idpf_rx_buf_alloc_singleq(struct idpf_rx_queue *rxq)
>  static int idpf_rx_bufs_init_singleq(struct idpf_rx_queue *rxq)
>  {
>  	struct libeth_fq fq = {
> -		.count	= rxq->desc_count,
> -		.type	= LIBETH_FQE_MTU,
> -		.nid	= idpf_q_vector_to_mem(rxq->q_vector),
> +		.count		= rxq->desc_count,
> +		.type		= LIBETH_FQE_MTU,
> +		.buf_len	= IDPF_RX_MAX_BUF_SZ,
> +		.nid		= idpf_q_vector_to_mem(rxq->q_vector),
>  	};
>  	int ret;
>  
> @@ -754,6 +755,7 @@ static int idpf_rx_bufs_init(struct idpf_buf_queue *bufq,
>  		.truesize	= bufq->truesize,
>  		.count		= bufq->desc_count,
>  		.type		= type,
> +		.buf_len	= IDPF_RX_MAX_BUF_SZ,
>  		.hsplit		= idpf_queue_has(HSPLIT_EN, bufq),
>  		.xdp		= idpf_xdp_enabled(bufq->q_vector->vport),
>  		.nid		= idpf_q_vector_to_mem(bufq->q_vector),
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.h b/drivers/net/ethernet/intel/idpf/idpf_txrx.h
> index 75b977094741..a1255099656f 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.h
> +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.h
> @@ -101,6 +101,7 @@ do {								\
>  		idx = 0;					\
>  } while (0)
>  
> +#define IDPF_RX_MAX_BUF_SZ			(16384 - 128)
>  #define IDPF_RX_BUF_STRIDE			32
>  #define IDPF_RX_BUF_POST_STRIDE			16
>  #define IDPF_LOW_WATERMARK			64


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Re: [Intel-wired-lan] [PATCH iwl-net] idpf: cap maximum Rx buffer size

[Loktionov, Aleksandr]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf
> Of Joshua Hay
> Sent: Monday, November 3, 2025 10:21 PM
> To: intel-wired-lan@lists.osuosl.org
> Cc: netdev@vger.kernel.org; Hay, Joshua A <joshua.a.hay@intel.com>;
> Lobakin, Aleksander <aleksander.lobakin@intel.com>; Chittim, Madhu
> <madhu.chittim@intel.com>
> Subject: [Intel-wired-lan] [PATCH iwl-net] idpf: cap maximum Rx buffer
> size
> 
> The HW only supports a maximum Rx buffer size of 16K-128. On systems
> using large pages, the libeth logic can configure the buffer size to
> be larger than this. The upper bound is PAGE_SIZE while the lower
> bound is MTU rounded up to the nearest power of 2. For example, ARM
> systems with a 64K page size and an mtu of 9000 will set the Rx buffer
> size to 16K, which will cause the config Rx queues message to fail.
> 
> Initialize the bufq/fill queue buf_len field to the maximum supported
> size. This will trigger the libeth logic to cap the maximum Rx buffer
> size by reducing the upper bound.
> 
> Fixes: 74d1412ac8f37 ("idpf: use libeth Rx buffer management for
> payload buffer")
> Signed-off-by: Joshua Hay <joshua.a.hay@intel.com>
> Acked-by: Alexander Lobakin <aleksander.lobakin@intel.com>
> Reviewed-by: Madhu Chittim <madhu.chittim@intel.com>
> ---
>  drivers/net/ethernet/intel/idpf/idpf_txrx.c | 8 +++++---
> drivers/net/ethernet/intel/idpf/idpf_txrx.h | 1 +
>  2 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> index 828f7c444d30..dcdd4fef1c7a 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> @@ -695,9 +695,10 @@ static int idpf_rx_buf_alloc_singleq(struct
> idpf_rx_queue *rxq)  static int idpf_rx_bufs_init_singleq(struct
> idpf_rx_queue *rxq)  {
>  	struct libeth_fq fq = {
> -		.count	= rxq->desc_count,
> -		.type	= LIBETH_FQE_MTU,
> -		.nid	= idpf_q_vector_to_mem(rxq->q_vector),
> +		.count		= rxq->desc_count,
> +		.type		= LIBETH_FQE_MTU,
> +		.buf_len	= IDPF_RX_MAX_BUF_SZ,
> +		.nid		= idpf_q_vector_to_mem(rxq->q_vector),
>  	};
>  	int ret;
> 
> @@ -754,6 +755,7 @@ static int idpf_rx_bufs_init(struct idpf_buf_queue
> *bufq,
>  		.truesize	= bufq->truesize,
>  		.count		= bufq->desc_count,
>  		.type		= type,
> +		.buf_len	= IDPF_RX_MAX_BUF_SZ,
>  		.hsplit		= idpf_queue_has(HSPLIT_EN, bufq),
>  		.xdp		= idpf_xdp_enabled(bufq->q_vector->vport),
>  		.nid		= idpf_q_vector_to_mem(bufq->q_vector),
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.h
> b/drivers/net/ethernet/intel/idpf/idpf_txrx.h
> index 75b977094741..a1255099656f 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.h
> +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.h
> @@ -101,6 +101,7 @@ do {
> 	\
>  		idx = 0;					\
>  } while (0)
> 
> +#define IDPF_RX_MAX_BUF_SZ			(16384 - 128)
>  #define IDPF_RX_BUF_STRIDE			32
>  #define IDPF_RX_BUF_POST_STRIDE			16
>  #define IDPF_LOW_WATERMARK			64
> --
> 2.39.2

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>

Re: [Intel-wired-lan] [PATCH iwl-net] idpf: cap maximum Rx buffer size

[David Decotigny via Intel-wired-lan]

On 11/3/2025 1:20 PM, Joshua Hay wrote:
> The HW only supports a maximum Rx buffer size of 16K-128. On systems
> using large pages, the libeth logic can configure the buffer size to be
> larger than this. The upper bound is PAGE_SIZE while the lower bound is
> MTU rounded up to the nearest power of 2. For example, ARM systems with
> a 64K page size and an mtu of 9000 will set the Rx buffer size to 16K,
> which will cause the config Rx queues message to fail.
> 
> Initialize the bufq/fill queue buf_len field to the maximum supported
> size. This will trigger the libeth logic to cap the maximum Rx buffer
> size by reducing the upper bound.
> 
> Fixes: 74d1412ac8f37 ("idpf: use libeth Rx buffer management for payload buffer")
> Signed-off-by: Joshua Hay <joshua.a.hay@intel.com>
> Acked-by: Alexander Lobakin <aleksander.lobakin@intel.com>
> Reviewed-by: Madhu Chittim <madhu.chittim@intel.com>
> ---

Reviewed-by: David Decotigny <ddecotig@google.com>