[net] sfc: check hash is valid before using it

On EF100, the RX hash field in the packet prefix may not be valid (e.g.
 if the header parse failed), and this is indicated by a one-bit flag
 elsewhere in the packet prefix.  Only call skb_set_hash() if the
 RSS_HASH_VALID bit is set.

Signed-off-by: Edward Cree <ecree@solarflare.com>
---
 drivers/net/ethernet/sfc/ef100_rx.c   | 5 +++++
 drivers/net/ethernet/sfc/ef100_rx.h   | 1 +
 drivers/net/ethernet/sfc/efx.h        | 8 ++++++++
 drivers/net/ethernet/sfc/net_driver.h | 2 ++
 drivers/net/ethernet/sfc/rx_common.c  | 3 ++-
 5 files changed, 18 insertions(+), 1 deletion(-)

From: Edward Cree <ecree@solarflare.com>
Date: Fri, 14 Aug 2020 13:26:22 +0100

> On EF100, the RX hash field in the packet prefix may not be valid (e.g.
>  if the header parse failed), and this is indicated by a one-bit flag
>  elsewhere in the packet prefix.  Only call skb_set_hash() if the
>  RSS_HASH_VALID bit is set.
> 
> Signed-off-by: Edward Cree <ecree@solarflare.com>

Applied.

Hi Ed,

On Fri, Aug 14, 2020 at 01:26:22PM +0100, Edward Cree wrote:
> On EF100, the RX hash field in the packet prefix may not be valid (e.g.
>  if the header parse failed), and this is indicated by a one-bit flag
>  elsewhere in the packet prefix.  Only call skb_set_hash() if the
>  RSS_HASH_VALID bit is set.
> 
> Signed-off-by: Edward Cree <ecree@solarflare.com>
> ---
>  drivers/net/ethernet/sfc/ef100_rx.c   | 5 +++++
>  drivers/net/ethernet/sfc/ef100_rx.h   | 1 +
>  drivers/net/ethernet/sfc/efx.h        | 8 ++++++++
>  drivers/net/ethernet/sfc/net_driver.h | 2 ++
>  drivers/net/ethernet/sfc/rx_common.c  | 3 ++-
>  5 files changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/sfc/ef100_rx.c b/drivers/net/ethernet/sfc/ef100_rx.c
> index 13ba1a4f66fc..012925e878f4 100644
> --- a/drivers/net/ethernet/sfc/ef100_rx.c
> +++ b/drivers/net/ethernet/sfc/ef100_rx.c
> @@ -31,6 +31,11 @@
>  #define ESF_GZ_RX_PREFIX_NT_OR_INNER_L3_CLASS_WIDTH	\
>  		ESF_GZ_RX_PREFIX_HCLASS_NT_OR_INNER_L3_CLASS_WIDTH
>  
> +bool ef100_rx_buf_hash_valid(const u8 *prefix)
> +{
> +	return PREFIX_FIELD(prefix, RSS_HASH_VALID);
> +}
> +
>  static bool check_fcs(struct efx_channel *channel, u32 *prefix)
>  {
>  	u16 rxclass;
> diff --git a/drivers/net/ethernet/sfc/ef100_rx.h b/drivers/net/ethernet/sfc/ef100_rx.h
> index f2f266863966..fe45b36458d1 100644
> --- a/drivers/net/ethernet/sfc/ef100_rx.h
> +++ b/drivers/net/ethernet/sfc/ef100_rx.h
> @@ -14,6 +14,7 @@
>  
>  #include "net_driver.h"
>  
> +bool ef100_rx_buf_hash_valid(const u8 *prefix);
>  void efx_ef100_ev_rx(struct efx_channel *channel, const efx_qword_t *p_event);
>  void ef100_rx_write(struct efx_rx_queue *rx_queue);
>  void __ef100_rx_packet(struct efx_channel *channel);
> diff --git a/drivers/net/ethernet/sfc/efx.h b/drivers/net/ethernet/sfc/efx.h
> index a9808e86068d..daf0c00c1242 100644
> --- a/drivers/net/ethernet/sfc/efx.h
> +++ b/drivers/net/ethernet/sfc/efx.h
> @@ -45,6 +45,14 @@ static inline void efx_rx_flush_packet(struct efx_channel *channel)
>  				__ef100_rx_packet, __efx_rx_packet,
>  				channel);
>  }
> +static inline bool efx_rx_buf_hash_valid(struct efx_nic *efx, const u8 *prefix)
> +{
> +	if (efx->type->rx_buf_hash_valid)

For this to take effect you still need to hook up efx->type->rx_buf_hash_valid
in the ef100_nic.c efx_nic_type structs.

Martin

> +		return INDIRECT_CALL_1(efx->type->rx_buf_hash_valid,
> +				       ef100_rx_buf_hash_valid,
> +				       prefix);
> +	return true;
> +}
>  
>  /* Maximum number of TCP segments we support for soft-TSO */
>  #define EFX_TSO_MAX_SEGS	100
> diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
> index 7bb7ecb480ae..dcb741d8bd11 100644
> --- a/drivers/net/ethernet/sfc/net_driver.h
> +++ b/drivers/net/ethernet/sfc/net_driver.h
> @@ -1265,6 +1265,7 @@ struct efx_udp_tunnel {
>   * @rx_write: Write RX descriptors and doorbell
>   * @rx_defer_refill: Generate a refill reminder event
>   * @rx_packet: Receive the queued RX buffer on a channel
> + * @rx_buf_hash_valid: Determine whether the RX prefix contains a valid hash
>   * @ev_probe: Allocate resources for event queue
>   * @ev_init: Initialise event queue on the NIC
>   * @ev_fini: Deinitialise event queue on the NIC
> @@ -1409,6 +1410,7 @@ struct efx_nic_type {
>  	void (*rx_write)(struct efx_rx_queue *rx_queue);
>  	void (*rx_defer_refill)(struct efx_rx_queue *rx_queue);
>  	void (*rx_packet)(struct efx_channel *channel);
> +	bool (*rx_buf_hash_valid)(const u8 *prefix);
>  	int (*ev_probe)(struct efx_channel *channel);
>  	int (*ev_init)(struct efx_channel *channel);
>  	void (*ev_fini)(struct efx_channel *channel);
> diff --git a/drivers/net/ethernet/sfc/rx_common.c b/drivers/net/ethernet/sfc/rx_common.c
> index fb77c7bbe4af..ef9bca92b0b7 100644
> --- a/drivers/net/ethernet/sfc/rx_common.c
> +++ b/drivers/net/ethernet/sfc/rx_common.c
> @@ -525,7 +525,8 @@ efx_rx_packet_gro(struct efx_channel *channel, struct efx_rx_buffer *rx_buf,
>  		return;
>  	}
>  
> -	if (efx->net_dev->features & NETIF_F_RXHASH)
> +	if (efx->net_dev->features & NETIF_F_RXHASH &&
> +	    efx_rx_buf_hash_valid(efx, eh))
>  		skb_set_hash(skb, efx_rx_buf_hash(efx, eh),
>  			     PKT_HASH_TYPE_L3);
>  	if (csum) {