net/mlx5e: Consider internal buffers size in port buffer calculations

Currently, when a user triggers a change in port buffer headroom
(buffers 0-7), the driver checks that the requested headroom does
not exceed the total port buffer size. However, this check does not
take into account the internal buffers (buffers 8-9), which are also
part of the total port buffer. This can result in treating invalid port
buffer change requests as valid, causing unintended changes to the shared
buffer.

To address this, include the internal buffers size in the calculation of
available port buffer space which ensures that port buffer requests do not
exceed the correct limit.

Furthermore, remove internal buffers (8-9) size from the total_size
calculation as these buffers are reserved for internal use and are not
exposed to the user.

While at it, add verbosity to the debug prints in
mlx5e_port_query_buffer() function to ease future debugging.

Fixes: ecdf2dad ("net/mlx5e: Receive buffer support for DCBX")
Signed-off-by: Maher Sanalla <msanalla@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en/port_buffer.c

@@ -51,7 +51,7 @@ int mlx5e_port_query_buffer(struct mlx5e_priv *priv,
 	if (err)
 		goto out;
 
-	for (i = 0; i < MLX5E_MAX_BUFFER; i++) {
+	for (i = 0; i < MLX5E_MAX_NETWORK_BUFFER; i++) {
 		buffer = MLX5_ADDR_OF(pbmc_reg, out, buffer[i]);
 		port_buffer->buffer[i].lossy =
 			MLX5_GET(bufferx_reg, buffer, lossy);
@@ -73,14 +73,24 @@ int mlx5e_port_query_buffer(struct mlx5e_priv *priv,
 			  port_buffer->buffer[i].lossy);
 	}
 
-	port_buffer->headroom_size = total_used;
+	port_buffer->internal_buffers_size = 0;
+	for (i = MLX5E_MAX_NETWORK_BUFFER; i < MLX5E_TOTAL_BUFFERS; i++) {
+		buffer = MLX5_ADDR_OF(pbmc_reg, out, buffer[i]);
+		port_buffer->internal_buffers_size +=
+			MLX5_GET(bufferx_reg, buffer, size) * port_buff_cell_sz;
+	}
+
 	port_buffer->port_buffer_size =
 		MLX5_GET(pbmc_reg, out, port_buffer_size) * port_buff_cell_sz;
-	port_buffer->spare_buffer_size =
-		port_buffer->port_buffer_size - total_used;
-
-	mlx5e_dbg(HW, priv, "total buffer size=%d, spare buffer size=%d\n",
-		  port_buffer->port_buffer_size,
+	port_buffer->headroom_size = total_used;
+	port_buffer->spare_buffer_size = port_buffer->port_buffer_size -
+					 port_buffer->internal_buffers_size -
+					 port_buffer->headroom_size;
+
+	mlx5e_dbg(HW, priv,
+		  "total buffer size=%u, headroom buffer size=%u, internal buffers size=%u, spare buffer size=%u\n",
+		  port_buffer->port_buffer_size, port_buffer->headroom_size,
+		  port_buffer->internal_buffers_size,
 		  port_buffer->spare_buffer_size);
 out:
 	kfree(out);
@@ -206,11 +216,11 @@ static int port_update_pool_cfg(struct mlx5_core_dev *mdev,
 	if (!MLX5_CAP_GEN(mdev, sbcam_reg))
 		return 0;
 
-	for (i = 0; i < MLX5E_MAX_BUFFER; i++)
+	for (i = 0; i < MLX5E_MAX_NETWORK_BUFFER; i++)
 		lossless_buff_count += ((port_buffer->buffer[i].size) &&
 				       (!(port_buffer->buffer[i].lossy)));
 
-	for (i = 0; i < MLX5E_MAX_BUFFER; i++) {
+	for (i = 0; i < MLX5E_MAX_NETWORK_BUFFER; i++) {
 		p = select_sbcm_params(&port_buffer->buffer[i], lossless_buff_count);
 		err = mlx5e_port_set_sbcm(mdev, 0, i,
 					  MLX5_INGRESS_DIR,
@@ -293,7 +303,7 @@ static int port_set_buffer(struct mlx5e_priv *priv,
 	if (err)
 		goto out;
 
-	for (i = 0; i < MLX5E_MAX_BUFFER; i++) {
+	for (i = 0; i < MLX5E_MAX_NETWORK_BUFFER; i++) {
 		void *buffer = MLX5_ADDR_OF(pbmc_reg, in, buffer[i]);
 		u64 size = port_buffer->buffer[i].size;
 		u64 xoff = port_buffer->buffer[i].xoff;
@@ -351,7 +361,7 @@ static int update_xoff_threshold(struct mlx5e_port_buffer *port_buffer,
 {
 	int i;
 
-	for (i = 0; i < MLX5E_MAX_BUFFER; i++) {
+	for (i = 0; i < MLX5E_MAX_NETWORK_BUFFER; i++) {
 		if (port_buffer->buffer[i].lossy) {
 			port_buffer->buffer[i].xoff = 0;
 			port_buffer->buffer[i].xon  = 0;
@@ -408,7 +418,7 @@ static int update_buffer_lossy(struct mlx5_core_dev *mdev,
 	int err;
 	int i;
 
-	for (i = 0; i < MLX5E_MAX_BUFFER; i++) {
+	for (i = 0; i < MLX5E_MAX_NETWORK_BUFFER; i++) {
 		prio_count = 0;
 		lossy_count = 0;
 
@@ -515,7 +525,7 @@ int mlx5e_port_manual_buffer_config(struct mlx5e_priv *priv,
 
 	if (change & MLX5E_PORT_BUFFER_PRIO2BUFFER) {
 		update_prio2buffer = true;
-		for (i = 0; i < MLX5E_MAX_BUFFER; i++)
+		for (i = 0; i < MLX5E_MAX_NETWORK_BUFFER; i++)
 			mlx5e_dbg(HW, priv, "%s: requested to map prio[%d] to buffer %d\n",
 				  __func__, i, prio2buffer[i]);
 
@@ -530,7 +540,7 @@ int mlx5e_port_manual_buffer_config(struct mlx5e_priv *priv,
 	}
 
 	if (change & MLX5E_PORT_BUFFER_SIZE) {
-		for (i = 0; i < MLX5E_MAX_BUFFER; i++) {
+		for (i = 0; i < MLX5E_MAX_NETWORK_BUFFER; i++) {
 			mlx5e_dbg(HW, priv, "%s: buffer[%d]=%d\n", __func__, i, buffer_size[i]);
 			if (!port_buffer.buffer[i].lossy && !buffer_size[i]) {
 				mlx5e_dbg(HW, priv, "%s: lossless buffer[%d] size cannot be zero\n",
@@ -544,7 +554,9 @@ int mlx5e_port_manual_buffer_config(struct mlx5e_priv *priv,
 
 		mlx5e_dbg(HW, priv, "%s: total buffer requested=%d\n", __func__, total_used);
 
-		if (total_used > port_buffer.port_buffer_size)
+		if (total_used > port_buffer.headroom_size &&
+		    (total_used - port_buffer.headroom_size) >
+			    port_buffer.spare_buffer_size)
 			return -EINVAL;
 
 		update_buffer = true;

drivers/net/ethernet/mellanox/mlx5/core/en/port_buffer.h

@@ -35,7 +35,8 @@
 #include "en.h"
 #include "port.h"
 
-#define MLX5E_MAX_BUFFER 8
+#define MLX5E_MAX_NETWORK_BUFFER 8
+#define MLX5E_TOTAL_BUFFERS 10
 #define MLX5E_DEFAULT_CABLE_LEN 7 /* 7 meters */
 
 #define MLX5_BUFFER_SUPPORTED(mdev) (MLX5_CAP_GEN(mdev, pcam_reg) && \
@@ -60,8 +61,9 @@ struct mlx5e_bufferx_reg {
 struct mlx5e_port_buffer {
 	u32                       port_buffer_size;
 	u32                       spare_buffer_size;
-	u32                       headroom_size;
-	struct mlx5e_bufferx_reg  buffer[MLX5E_MAX_BUFFER];
+	u32                       headroom_size;	  /* Buffers 0-7 */
+	u32                       internal_buffers_size;  /* Buffers 8-9 */
+	struct mlx5e_bufferx_reg  buffer[MLX5E_MAX_NETWORK_BUFFER];
 };
 
 int mlx5e_port_manual_buffer_config(struct mlx5e_priv *priv,

drivers/net/ethernet/mellanox/mlx5/core/en_dcbnl.c

@@ -926,9 +926,10 @@ static int mlx5e_dcbnl_getbuffer(struct net_device *dev,
 	if (err)
 		return err;
 
-	for (i = 0; i < MLX5E_MAX_BUFFER; i++)
+	for (i = 0; i < MLX5E_MAX_NETWORK_BUFFER; i++)
 		dcb_buffer->buffer_size[i] = port_buffer.buffer[i].size;
-	dcb_buffer->total_size = port_buffer.port_buffer_size;
+	dcb_buffer->total_size = port_buffer.port_buffer_size -
+				 port_buffer.internal_buffers_size;
 
 	return 0;
 }
@@ -970,7 +971,7 @@ static int mlx5e_dcbnl_setbuffer(struct net_device *dev,
 	if (err)
 		return err;
 
-	for (i = 0; i < MLX5E_MAX_BUFFER; i++) {
+	for (i = 0; i < MLX5E_MAX_NETWORK_BUFFER; i++) {
 		if (port_buffer.buffer[i].size != dcb_buffer->buffer_size[i]) {
 			changed |= MLX5E_PORT_BUFFER_SIZE;
 			buffer_size = dcb_buffer->buffer_size;