[PATCH v3 1/4] wifi: ath12k: fix dest ring-buffer corruption

[PATCH v3 1/4] wifi: ath12k: 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 ath12k_hal_srng_access_begin() helper for
symmetry with follow-on fixes for source ring buffer corruption which
will add barriers to ath12k_hal_srng_access_end().

Tested-on: WCN7850 hw2.0 WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Cc: stable@vger.kernel.org	# 6.3
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/net/wireless/ath/ath12k/ce.c  |  3 ---
 drivers/net/wireless/ath/ath12k/hal.c | 17 ++++++++++++++---
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/ath/ath12k/ce.c b/drivers/net/wireless/ath/ath12k/ce.c
index 3f3439262cf4..f7c15b547504 100644
--- a/drivers/net/wireless/ath/ath12k/ce.c
+++ b/drivers/net/wireless/ath/ath12k/ce.c
@@ -433,9 +433,6 @@ static int ath12k_ce_completed_recv_next(struct ath12k_ce_pipe *pipe,
 		goto err;
 	}
 
-	/* Make sure descriptor is read after the head pointer. */
-	dma_rmb();
-
 	*nbytes = ath12k_hal_ce_dst_status_get_length(desc);
 
 	*skb = pipe->dest_ring->skb[sw_index];
diff --git a/drivers/net/wireless/ath/ath12k/hal.c b/drivers/net/wireless/ath/ath12k/hal.c
index a301898e5849..f8bd3837b9dc 100644
--- a/drivers/net/wireless/ath/ath12k/hal.c
+++ b/drivers/net/wireless/ath/ath12k/hal.c
@@ -2143,13 +2143,24 @@ void *ath12k_hal_srng_src_get_next_reaped(struct ath12k_base *ab,
 
 void ath12k_hal_srng_access_begin(struct ath12k_base *ab, struct hal_srng *srng)
 {
+	u32 hp;
+
 	lockdep_assert_held(&srng->lock);
 
-	if (srng->ring_dir == HAL_SRNG_DIR_SRC)
+	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);
+	} else {
+		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();
+		}
+	}
 }
 
 /* Update cached ring head/tail pointers to HW. ath12k_hal_srng_access_begin()
-- 
2.49.0

[PATCH v3 3/4] wifi: ath12k: 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: WCN7850 hw2.0 WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Cc: stable@vger.kernel.org      # 6.3
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/net/wireless/ath/ath12k/hal.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath12k/hal.c b/drivers/net/wireless/ath/ath12k/hal.c
index 726969cfcaec..d8193d9577bb 100644
--- a/drivers/net/wireless/ath/ath12k/hal.c
+++ b/drivers/net/wireless/ath/ath12k/hal.c
@@ -2178,7 +2178,11 @@ void ath12k_hal_srng_access_end(struct ath12k_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;
@@ -2187,6 +2191,10 @@ void ath12k_hal_srng_access_end(struct ath12k_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.
+			 */
 			ath12k_hif_write32(ab,
 					   (unsigned long)srng->u.src_ring.hp_addr -
 					   (unsigned long)ab->mem,
-- 
2.49.0

[PATCH v3 4/4] wifi: ath12k: 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: WCN7850 hw2.0 WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Cc: stable@vger.kernel.org      # 6.3
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/net/wireless/ath/ath12k/hal.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath12k/hal.c b/drivers/net/wireless/ath/ath12k/hal.c
index d8193d9577bb..6406fcf5d69f 100644
--- a/drivers/net/wireless/ath/ath12k/hal.c
+++ b/drivers/net/wireless/ath/ath12k/hal.c
@@ -2170,7 +2170,6 @@ void ath12k_hal_srng_access_end(struct ath12k_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
@@ -2185,7 +2184,11 @@ void ath12k_hal_srng_access_end(struct ath12k_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) {
@@ -2201,6 +2204,10 @@ void ath12k_hal_srng_access_end(struct ath12k_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();
 			ath12k_hif_write32(ab,
 					   (unsigned long)srng->u.dst_ring.tp_addr -
 					   (unsigned long)ab->mem,
-- 
2.49.0

Re: [PATCH v3 1/4] wifi: ath12k: fix dest ring-buffer corruption

[Baochen Qiang]

On 6/17/2025 4:43 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 ath12k_hal_srng_access_begin() helper for
> symmetry with follow-on fixes for source ring buffer corruption which
> will add barriers to ath12k_hal_srng_access_end().
> 
> Tested-on: WCN7850 hw2.0 WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3
> 
> Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
> Cc: stable@vger.kernel.org	# 6.3
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/net/wireless/ath/ath12k/ce.c  |  3 ---
>  drivers/net/wireless/ath/ath12k/hal.c | 17 ++++++++++++++---
>  2 files changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath12k/ce.c b/drivers/net/wireless/ath/ath12k/ce.c
> index 3f3439262cf4..f7c15b547504 100644
> --- a/drivers/net/wireless/ath/ath12k/ce.c
> +++ b/drivers/net/wireless/ath/ath12k/ce.c
> @@ -433,9 +433,6 @@ static int ath12k_ce_completed_recv_next(struct ath12k_ce_pipe *pipe,
>  		goto err;
>  	}
>  
> -	/* Make sure descriptor is read after the head pointer. */
> -	dma_rmb();
> -
>  	*nbytes = ath12k_hal_ce_dst_status_get_length(desc);
>  
>  	*skb = pipe->dest_ring->skb[sw_index];
> diff --git a/drivers/net/wireless/ath/ath12k/hal.c b/drivers/net/wireless/ath/ath12k/hal.c
> index a301898e5849..f8bd3837b9dc 100644
> --- a/drivers/net/wireless/ath/ath12k/hal.c
> +++ b/drivers/net/wireless/ath/ath12k/hal.c
> @@ -2143,13 +2143,24 @@ void *ath12k_hal_srng_src_get_next_reaped(struct ath12k_base *ab,
>  
>  void ath12k_hal_srng_access_begin(struct ath12k_base *ab, struct hal_srng *srng)
>  {
> +	u32 hp;
> +
>  	lockdep_assert_held(&srng->lock);
>  
> -	if (srng->ring_dir == HAL_SRNG_DIR_SRC)
> +	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);
> +	} else {
> +		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();
> +		}
> +	}
>  }
>  
>  /* Update cached ring head/tail pointers to HW. ath12k_hal_srng_access_begin()

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

Re: [PATCH v3 3/4] wifi: ath12k: fix source ring-buffer corruption

[Baochen Qiang]

On 6/17/2025 4:44 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: WCN7850 hw2.0 WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3
> 
> Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
> Cc: stable@vger.kernel.org      # 6.3
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/net/wireless/ath/ath12k/hal.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/ath/ath12k/hal.c b/drivers/net/wireless/ath/ath12k/hal.c
> index 726969cfcaec..d8193d9577bb 100644
> --- a/drivers/net/wireless/ath/ath12k/hal.c
> +++ b/drivers/net/wireless/ath/ath12k/hal.c
> @@ -2178,7 +2178,11 @@ void ath12k_hal_srng_access_end(struct ath12k_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;
> @@ -2187,6 +2191,10 @@ void ath12k_hal_srng_access_end(struct ath12k_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.
> +			 */
>  			ath12k_hif_write32(ab,
>  					   (unsigned long)srng->u.src_ring.hp_addr -
>  					   (unsigned long)ab->mem,

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

Re: [PATCH v3 4/4] wifi: ath12k: fix dest ring-buffer corruption when ring is full

[Baochen Qiang]

On 6/17/2025 4:44 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: WCN7850 hw2.0 WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3
> 
> Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
> Cc: stable@vger.kernel.org      # 6.3
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/net/wireless/ath/ath12k/hal.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath12k/hal.c b/drivers/net/wireless/ath/ath12k/hal.c
> index d8193d9577bb..6406fcf5d69f 100644
> --- a/drivers/net/wireless/ath/ath12k/hal.c
> +++ b/drivers/net/wireless/ath/ath12k/hal.c
> @@ -2170,7 +2170,6 @@ void ath12k_hal_srng_access_end(struct ath12k_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
> @@ -2185,7 +2184,11 @@ void ath12k_hal_srng_access_end(struct ath12k_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) {
> @@ -2201,6 +2204,10 @@ void ath12k_hal_srng_access_end(struct ath12k_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();
>  			ath12k_hif_write32(ab,
>  					   (unsigned long)srng->u.dst_ring.tp_addr -
>  					   (unsigned long)ab->mem,

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