sfc: Use separate hardware TX queues to select checksum generation

Checksum generation is an attribute of our hardware TX queues, not TX
descriptors.  We previously used a single queue and turned checksum
generation on or off as requested through ethtool.  However, this can
result in regenerating checksums in raw packets that should not be
modified.  We now create 2 hardware TX queues with checksum generation
on or off.  They are presented to the net core as one queue since it
does not know how to select between them.

The self-test verifies that a bad checksum is unaltered on the queue
with checksum generation off.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/drivers/net/sfc/falcon.c b/drivers/net/sfc/falcon.c
index c7aa2f61cb1c..b73f1ea8bd58 100644
--- a/drivers/net/sfc/falcon.c
+++ b/drivers/net/sfc/falcon.c
@@ -474,9 +474,9 @@ int falcon_init_tx(struct efx_tx_queue *tx_queue)
                               TX_NON_IP_DROP_DIS_B0, 1);
 
         if (falcon_rev(efx) >= FALCON_REV_B0) {
-                int csum = !(efx->net_dev->features & NETIF_F_IP_CSUM);
-                EFX_SET_OWORD_FIELD(tx_desc_ptr, TX_IP_CHKSM_DIS_B0, csum);
-                EFX_SET_OWORD_FIELD(tx_desc_ptr, TX_TCP_CHKSM_DIS_B0, csum);
+                int csum = tx_queue->queue == EFX_TX_QUEUE_OFFLOAD_CSUM;
+                EFX_SET_OWORD_FIELD(tx_desc_ptr, TX_IP_CHKSM_DIS_B0, !csum);
+                EFX_SET_OWORD_FIELD(tx_desc_ptr, TX_TCP_CHKSM_DIS_B0, !csum);
         }
 
         falcon_write_table(efx, &tx_desc_ptr, efx->type->txd_ptr_tbl_base,
@@ -485,10 +485,11 @@ int falcon_init_tx(struct efx_tx_queue *tx_queue)
         if (falcon_rev(efx) < FALCON_REV_B0) {
                 efx_oword_t reg;
 
-                BUG_ON(tx_queue->queue >= 128); /* HW limit */
+                /* Only 128 bits in this register */
+                BUILD_BUG_ON(EFX_TX_QUEUE_COUNT >= 128);
 
                 falcon_read(efx, &reg, TX_CHKSM_CFG_REG_KER_A1);
-                if (efx->net_dev->features & NETIF_F_IP_CSUM)
+                if (tx_queue->queue == EFX_TX_QUEUE_OFFLOAD_CSUM)
                         clear_bit_le(tx_queue->queue, (void *)&reg);
                 else
                         set_bit_le(tx_queue->queue, (void *)&reg);