[PATCH v2 1/5] wifi: ath11k: fix dest ring-buffer corruption

[PATCH v2 1/5] wifi: ath11k: fix dest ring-buffer corruption

[Johan Hovold]

Add the missing memory barrier to make sure that destination ring
descriptors are read after the head pointers to avoid using stale data
on weakly ordered architectures like aarch64.

The barrier is added to the ath11k_hal_srng_access_begin() helper for
symmetry with follow-on fixes for source ring buffer corruption which
will add barriers to ath11k_hal_srng_access_end().

Tested-on: WCN6855 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Cc: stable@vger.kernel.org	# 5.6
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/net/wireless/ath/ath11k/ce.c    |  3 ---
 drivers/net/wireless/ath/ath11k/dp_rx.c |  3 ---
 drivers/net/wireless/ath/ath11k/hal.c   | 12 +++++++++++-
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/ce.c b/drivers/net/wireless/ath/ath11k/ce.c
index 9d8efec46508..39d9aad33bc6 100644
--- a/drivers/net/wireless/ath/ath11k/ce.c
+++ b/drivers/net/wireless/ath/ath11k/ce.c
@@ -393,9 +393,6 @@ static int ath11k_ce_completed_recv_next(struct ath11k_ce_pipe *pipe,
 		goto err;
 	}
 
-	/* Make sure descriptor is read after the head pointer. */
-	dma_rmb();
-
 	*nbytes = ath11k_hal_ce_dst_status_get_length(desc);
 
 	*skb = pipe->dest_ring->skb[sw_index];
diff --git a/drivers/net/wireless/ath/ath11k/dp_rx.c b/drivers/net/wireless/ath/ath11k/dp_rx.c
index ea2959305dec..d8dab182a9af 100644
--- a/drivers/net/wireless/ath/ath11k/dp_rx.c
+++ b/drivers/net/wireless/ath/ath11k/dp_rx.c
@@ -2650,9 +2650,6 @@ int ath11k_dp_process_rx(struct ath11k_base *ab, int ring_id,
 try_again:
 	ath11k_hal_srng_access_begin(ab, srng);
 
-	/* Make sure descriptor is read after the head pointer. */
-	dma_rmb();
-
 	while (likely(desc =
 	      (struct hal_reo_dest_ring *)ath11k_hal_srng_dst_get_next_entry(ab,
 									     srng))) {
diff --git a/drivers/net/wireless/ath/ath11k/hal.c b/drivers/net/wireless/ath/ath11k/hal.c
index 8cb1505a5a0c..921114686ba3 100644
--- a/drivers/net/wireless/ath/ath11k/hal.c
+++ b/drivers/net/wireless/ath/ath11k/hal.c
@@ -823,13 +823,23 @@ u32 *ath11k_hal_srng_src_peek(struct ath11k_base *ab, struct hal_srng *srng)
 
 void ath11k_hal_srng_access_begin(struct ath11k_base *ab, struct hal_srng *srng)
 {
+	u32 hp;
+
 	lockdep_assert_held(&srng->lock);
 
 	if (srng->ring_dir == HAL_SRNG_DIR_SRC) {
 		srng->u.src_ring.cached_tp =
 			*(volatile u32 *)srng->u.src_ring.tp_addr;
 	} else {
-		srng->u.dst_ring.cached_hp = READ_ONCE(*srng->u.dst_ring.hp_addr);
+		hp = READ_ONCE(*srng->u.dst_ring.hp_addr);
+
+		if (hp != srng->u.dst_ring.cached_hp) {
+			srng->u.dst_ring.cached_hp = hp;
+			/* Make sure descriptor is read after the head
+			 * pointer.
+			 */
+			dma_rmb();
+		}
 
 		/* Try to prefetch the next descriptor in the ring */
 		if (srng->flags & HAL_SRNG_FLAGS_CACHED)
-- 
2.49.0

Re: [PATCH v2 1/5] wifi: ath11k: fix dest ring-buffer corruption

[Baochen Qiang]

On 6/4/2025 10:34 PM, Johan Hovold wrote:
> Add the missing memory barrier to make sure that destination ring
> descriptors are read after the head pointers to avoid using stale data
> on weakly ordered architectures like aarch64.
> 
> The barrier is added to the ath11k_hal_srng_access_begin() helper for
> symmetry with follow-on fixes for source ring buffer corruption which
> will add barriers to ath11k_hal_srng_access_end().
> 
> Tested-on: WCN6855 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41
> 
> Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
> Cc: stable@vger.kernel.org	# 5.6
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/net/wireless/ath/ath11k/ce.c    |  3 ---
>  drivers/net/wireless/ath/ath11k/dp_rx.c |  3 ---
>  drivers/net/wireless/ath/ath11k/hal.c   | 12 +++++++++++-
>  3 files changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath11k/ce.c b/drivers/net/wireless/ath/ath11k/ce.c
> index 9d8efec46508..39d9aad33bc6 100644
> --- a/drivers/net/wireless/ath/ath11k/ce.c
> +++ b/drivers/net/wireless/ath/ath11k/ce.c
> @@ -393,9 +393,6 @@ static int ath11k_ce_completed_recv_next(struct ath11k_ce_pipe *pipe,
>  		goto err;
>  	}
>  
> -	/* Make sure descriptor is read after the head pointer. */
> -	dma_rmb();
> -
>  	*nbytes = ath11k_hal_ce_dst_status_get_length(desc);
>  
>  	*skb = pipe->dest_ring->skb[sw_index];
> diff --git a/drivers/net/wireless/ath/ath11k/dp_rx.c b/drivers/net/wireless/ath/ath11k/dp_rx.c
> index ea2959305dec..d8dab182a9af 100644
> --- a/drivers/net/wireless/ath/ath11k/dp_rx.c
> +++ b/drivers/net/wireless/ath/ath11k/dp_rx.c
> @@ -2650,9 +2650,6 @@ int ath11k_dp_process_rx(struct ath11k_base *ab, int ring_id,
>  try_again:
>  	ath11k_hal_srng_access_begin(ab, srng);
>  
> -	/* Make sure descriptor is read after the head pointer. */
> -	dma_rmb();
> -
>  	while (likely(desc =
>  	      (struct hal_reo_dest_ring *)ath11k_hal_srng_dst_get_next_entry(ab,
>  									     srng))) {
> diff --git a/drivers/net/wireless/ath/ath11k/hal.c b/drivers/net/wireless/ath/ath11k/hal.c
> index 8cb1505a5a0c..921114686ba3 100644
> --- a/drivers/net/wireless/ath/ath11k/hal.c
> +++ b/drivers/net/wireless/ath/ath11k/hal.c
> @@ -823,13 +823,23 @@ u32 *ath11k_hal_srng_src_peek(struct ath11k_base *ab, struct hal_srng *srng)
>  
>  void ath11k_hal_srng_access_begin(struct ath11k_base *ab, struct hal_srng *srng)
>  {
> +	u32 hp;
> +
>  	lockdep_assert_held(&srng->lock);
>  
>  	if (srng->ring_dir == HAL_SRNG_DIR_SRC) {
>  		srng->u.src_ring.cached_tp =
>  			*(volatile u32 *)srng->u.src_ring.tp_addr;
>  	} else {
> -		srng->u.dst_ring.cached_hp = READ_ONCE(*srng->u.dst_ring.hp_addr);
> +		hp = READ_ONCE(*srng->u.dst_ring.hp_addr);
> +
> +		if (hp != srng->u.dst_ring.cached_hp) {

My ath12k comments apply here: this consumes more CPU cycles

> +			srng->u.dst_ring.cached_hp = hp;
> +			/* Make sure descriptor is read after the head
> +			 * pointer.
> +			 */
> +			dma_rmb();
> +		}
>  
>  		/* Try to prefetch the next descriptor in the ring */
>  		if (srng->flags & HAL_SRNG_FLAGS_CACHED)

Re: [PATCH v2 1/5] wifi: ath11k: fix dest ring-buffer corruption

[Baochen Qiang]

On 6/4/2025 10:34 PM, Johan Hovold wrote:
> Add the missing memory barrier to make sure that destination ring
> descriptors are read after the head pointers to avoid using stale data
> on weakly ordered architectures like aarch64.
> 
> The barrier is added to the ath11k_hal_srng_access_begin() helper for
> symmetry with follow-on fixes for source ring buffer corruption which
> will add barriers to ath11k_hal_srng_access_end().
> 
> Tested-on: WCN6855 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41
> 
> Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
> Cc: stable@vger.kernel.org	# 5.6
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/net/wireless/ath/ath11k/ce.c    |  3 ---
>  drivers/net/wireless/ath/ath11k/dp_rx.c |  3 ---
>  drivers/net/wireless/ath/ath11k/hal.c   | 12 +++++++++++-
>  3 files changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath11k/ce.c b/drivers/net/wireless/ath/ath11k/ce.c
> index 9d8efec46508..39d9aad33bc6 100644
> --- a/drivers/net/wireless/ath/ath11k/ce.c
> +++ b/drivers/net/wireless/ath/ath11k/ce.c
> @@ -393,9 +393,6 @@ static int ath11k_ce_completed_recv_next(struct ath11k_ce_pipe *pipe,
>  		goto err;
>  	}
>  
> -	/* Make sure descriptor is read after the head pointer. */
> -	dma_rmb();
> -
>  	*nbytes = ath11k_hal_ce_dst_status_get_length(desc);
>  
>  	*skb = pipe->dest_ring->skb[sw_index];
> diff --git a/drivers/net/wireless/ath/ath11k/dp_rx.c b/drivers/net/wireless/ath/ath11k/dp_rx.c
> index ea2959305dec..d8dab182a9af 100644
> --- a/drivers/net/wireless/ath/ath11k/dp_rx.c
> +++ b/drivers/net/wireless/ath/ath11k/dp_rx.c
> @@ -2650,9 +2650,6 @@ int ath11k_dp_process_rx(struct ath11k_base *ab, int ring_id,
>  try_again:
>  	ath11k_hal_srng_access_begin(ab, srng);
>  
> -	/* Make sure descriptor is read after the head pointer. */
> -	dma_rmb();
> -
>  	while (likely(desc =
>  	      (struct hal_reo_dest_ring *)ath11k_hal_srng_dst_get_next_entry(ab,
>  									     srng))) {
> diff --git a/drivers/net/wireless/ath/ath11k/hal.c b/drivers/net/wireless/ath/ath11k/hal.c
> index 8cb1505a5a0c..921114686ba3 100644
> --- a/drivers/net/wireless/ath/ath11k/hal.c
> +++ b/drivers/net/wireless/ath/ath11k/hal.c
> @@ -823,13 +823,23 @@ u32 *ath11k_hal_srng_src_peek(struct ath11k_base *ab, struct hal_srng *srng)
>  
>  void ath11k_hal_srng_access_begin(struct ath11k_base *ab, struct hal_srng *srng)
>  {
> +	u32 hp;
> +
>  	lockdep_assert_held(&srng->lock);
>  
>  	if (srng->ring_dir == HAL_SRNG_DIR_SRC) {
>  		srng->u.src_ring.cached_tp =
>  			*(volatile u32 *)srng->u.src_ring.tp_addr;
>  	} else {
> -		srng->u.dst_ring.cached_hp = READ_ONCE(*srng->u.dst_ring.hp_addr);
> +		hp = READ_ONCE(*srng->u.dst_ring.hp_addr);
> +
> +		if (hp != srng->u.dst_ring.cached_hp) {
> +			srng->u.dst_ring.cached_hp = hp;
> +			/* Make sure descriptor is read after the head
> +			 * pointer.
> +			 */
> +			dma_rmb();
> +		}
>  
>  		/* Try to prefetch the next descriptor in the ring */
>  		if (srng->flags & HAL_SRNG_FLAGS_CACHED)

Reviewed-by: Baochen Qiang <quic_bqiang@quicinc.com>

[PATCH v2 4/5] wifi: ath11k: fix source ring-buffer corruption

[Johan Hovold]

Add the missing memory barrier to make sure that LMAC source ring
descriptors are written before updating the head pointer to avoid
passing stale data to the firmware on weakly ordered architectures like
aarch64.

Note that non-LMAC rings use MMIO write accessors which have the
required write memory barrier.

Tested-on: WCN6855 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Cc: stable@vger.kernel.org      # 5.6
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/net/wireless/ath/ath11k/hal.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath11k/hal.c b/drivers/net/wireless/ath/ath11k/hal.c
index b1f5a927dddd..927ed2bc3fbf 100644
--- a/drivers/net/wireless/ath/ath11k/hal.c
+++ b/drivers/net/wireless/ath/ath11k/hal.c
@@ -862,7 +862,11 @@ void ath11k_hal_srng_access_end(struct ath11k_base *ab, struct hal_srng *srng)
 		if (srng->ring_dir == HAL_SRNG_DIR_SRC) {
 			srng->u.src_ring.last_tp =
 				*(volatile u32 *)srng->u.src_ring.tp_addr;
-			*srng->u.src_ring.hp_addr = srng->u.src_ring.hp;
+			/* Make sure descriptor is written before updating the
+			 * head pointer.
+			 */
+			dma_wmb();
+			WRITE_ONCE(*srng->u.src_ring.hp_addr, srng->u.src_ring.hp);
 		} else {
 			srng->u.dst_ring.last_hp = *srng->u.dst_ring.hp_addr;
 			*srng->u.dst_ring.tp_addr = srng->u.dst_ring.tp;
@@ -871,6 +875,10 @@ void ath11k_hal_srng_access_end(struct ath11k_base *ab, struct hal_srng *srng)
 		if (srng->ring_dir == HAL_SRNG_DIR_SRC) {
 			srng->u.src_ring.last_tp =
 				*(volatile u32 *)srng->u.src_ring.tp_addr;
+			/* Assume implementation use an MMIO write accessor
+			 * which has the required wmb() so that the descriptor
+			 * is written before the updating the head pointer.
+			 */
 			ath11k_hif_write32(ab,
 					   (unsigned long)srng->u.src_ring.hp_addr -
 					   (unsigned long)ab->mem,
-- 
2.49.0

Re: [PATCH v2 4/5] wifi: ath11k: fix source ring-buffer corruption

[Baochen Qiang]

On 6/4/2025 10:34 PM, Johan Hovold wrote:
> Add the missing memory barrier to make sure that LMAC source ring
> descriptors are written before updating the head pointer to avoid
> passing stale data to the firmware on weakly ordered architectures like
> aarch64.
> 
> Note that non-LMAC rings use MMIO write accessors which have the
> required write memory barrier.
> 
> Tested-on: WCN6855 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41
> 
> Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
> Cc: stable@vger.kernel.org      # 5.6
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/net/wireless/ath/ath11k/hal.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/ath/ath11k/hal.c b/drivers/net/wireless/ath/ath11k/hal.c
> index b1f5a927dddd..927ed2bc3fbf 100644
> --- a/drivers/net/wireless/ath/ath11k/hal.c
> +++ b/drivers/net/wireless/ath/ath11k/hal.c
> @@ -862,7 +862,11 @@ void ath11k_hal_srng_access_end(struct ath11k_base *ab, struct hal_srng *srng)
>  		if (srng->ring_dir == HAL_SRNG_DIR_SRC) {
>  			srng->u.src_ring.last_tp =
>  				*(volatile u32 *)srng->u.src_ring.tp_addr;
> -			*srng->u.src_ring.hp_addr = srng->u.src_ring.hp;
> +			/* Make sure descriptor is written before updating the
> +			 * head pointer.
> +			 */
> +			dma_wmb();
> +			WRITE_ONCE(*srng->u.src_ring.hp_addr, srng->u.src_ring.hp);
>  		} else {
>  			srng->u.dst_ring.last_hp = *srng->u.dst_ring.hp_addr;
>  			*srng->u.dst_ring.tp_addr = srng->u.dst_ring.tp;
> @@ -871,6 +875,10 @@ void ath11k_hal_srng_access_end(struct ath11k_base *ab, struct hal_srng *srng)
>  		if (srng->ring_dir == HAL_SRNG_DIR_SRC) {
>  			srng->u.src_ring.last_tp =
>  				*(volatile u32 *)srng->u.src_ring.tp_addr;
> +			/* Assume implementation use an MMIO write accessor
> +			 * which has the required wmb() so that the descriptor
> +			 * is written before the updating the head pointer.
> +			 */
>  			ath11k_hif_write32(ab,
>  					   (unsigned long)srng->u.src_ring.hp_addr -
>  					   (unsigned long)ab->mem,

Reviewed-by: Baochen Qiang <quic_bqiang@quicinc.com>

[PATCH v2 5/5] wifi: ath11k: fix dest ring-buffer corruption when ring is full

[Johan Hovold]

Add the missing memory barriers to make sure that destination ring
descriptors are read before updating the tail pointer (and passing
ownership to the device) to avoid memory corruption on weakly ordered
architectures like aarch64 when the ring is full.

Tested-on: WCN6855 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Cc: stable@vger.kernel.org      # 5.6
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/net/wireless/ath/ath11k/hal.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/hal.c b/drivers/net/wireless/ath/ath11k/hal.c
index 927ed2bc3fbf..7eeffb36899e 100644
--- a/drivers/net/wireless/ath/ath11k/hal.c
+++ b/drivers/net/wireless/ath/ath11k/hal.c
@@ -854,7 +854,6 @@ void ath11k_hal_srng_access_end(struct ath11k_base *ab, struct hal_srng *srng)
 {
 	lockdep_assert_held(&srng->lock);
 
-	/* TODO: See if we need a write memory barrier here */
 	if (srng->flags & HAL_SRNG_FLAGS_LMAC_RING) {
 		/* For LMAC rings, ring pointer updates are done through FW and
 		 * hence written to a shared memory location that is read by FW
@@ -869,7 +868,11 @@ void ath11k_hal_srng_access_end(struct ath11k_base *ab, struct hal_srng *srng)
 			WRITE_ONCE(*srng->u.src_ring.hp_addr, srng->u.src_ring.hp);
 		} else {
 			srng->u.dst_ring.last_hp = *srng->u.dst_ring.hp_addr;
-			*srng->u.dst_ring.tp_addr = srng->u.dst_ring.tp;
+			/* Make sure descriptor is read before updating the
+			 * tail pointer.
+			 */
+			dma_mb();
+			WRITE_ONCE(*srng->u.dst_ring.tp_addr, srng->u.dst_ring.tp);
 		}
 	} else {
 		if (srng->ring_dir == HAL_SRNG_DIR_SRC) {
@@ -885,6 +888,10 @@ void ath11k_hal_srng_access_end(struct ath11k_base *ab, struct hal_srng *srng)
 					   srng->u.src_ring.hp);
 		} else {
 			srng->u.dst_ring.last_hp = *srng->u.dst_ring.hp_addr;
+			/* Make sure descriptor is read before updating the
+			 * tail pointer.
+			 */
+			mb();
 			ath11k_hif_write32(ab,
 					   (unsigned long)srng->u.dst_ring.tp_addr -
 					   (unsigned long)ab->mem,
-- 
2.49.0

Re: [PATCH v2 5/5] wifi: ath11k: fix dest ring-buffer corruption when ring is full

[Baochen Qiang]

On 6/4/2025 10:34 PM, Johan Hovold wrote:
> Add the missing memory barriers to make sure that destination ring
> descriptors are read before updating the tail pointer (and passing
> ownership to the device) to avoid memory corruption on weakly ordered
> architectures like aarch64 when the ring is full.
> 
> Tested-on: WCN6855 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41
> 
> Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
> Cc: stable@vger.kernel.org      # 5.6
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/net/wireless/ath/ath11k/hal.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath11k/hal.c b/drivers/net/wireless/ath/ath11k/hal.c
> index 927ed2bc3fbf..7eeffb36899e 100644
> --- a/drivers/net/wireless/ath/ath11k/hal.c
> +++ b/drivers/net/wireless/ath/ath11k/hal.c
> @@ -854,7 +854,6 @@ void ath11k_hal_srng_access_end(struct ath11k_base *ab, struct hal_srng *srng)
>  {
>  	lockdep_assert_held(&srng->lock);
>  
> -	/* TODO: See if we need a write memory barrier here */
>  	if (srng->flags & HAL_SRNG_FLAGS_LMAC_RING) {
>  		/* For LMAC rings, ring pointer updates are done through FW and
>  		 * hence written to a shared memory location that is read by FW
> @@ -869,7 +868,11 @@ void ath11k_hal_srng_access_end(struct ath11k_base *ab, struct hal_srng *srng)
>  			WRITE_ONCE(*srng->u.src_ring.hp_addr, srng->u.src_ring.hp);
>  		} else {
>  			srng->u.dst_ring.last_hp = *srng->u.dst_ring.hp_addr;
> -			*srng->u.dst_ring.tp_addr = srng->u.dst_ring.tp;
> +			/* Make sure descriptor is read before updating the
> +			 * tail pointer.
> +			 */
> +			dma_mb();
> +			WRITE_ONCE(*srng->u.dst_ring.tp_addr, srng->u.dst_ring.tp);
>  		}
>  	} else {
>  		if (srng->ring_dir == HAL_SRNG_DIR_SRC) {
> @@ -885,6 +888,10 @@ void ath11k_hal_srng_access_end(struct ath11k_base *ab, struct hal_srng *srng)
>  					   srng->u.src_ring.hp);
>  		} else {
>  			srng->u.dst_ring.last_hp = *srng->u.dst_ring.hp_addr;
> +			/* Make sure descriptor is read before updating the
> +			 * tail pointer.
> +			 */
> +			mb();
>  			ath11k_hif_write32(ab,
>  					   (unsigned long)srng->u.dst_ring.tp_addr -
>  					   (unsigned long)ab->mem,

Reviewed-by: Baochen Qiang <quic_bqiang@quicinc.com>