From bd77f6b1d7104cf6451399a7c67d08afecb9a7c7 Mon Sep 17 00:00:00 2001
From: Rameshkumar Sundaram <quic_ramess@quicinc.com>
Date: Tue, 2 Nov 2021 11:11:33 +0530
Subject: [PATCH] ath11k: use cache line aligned buffers for dbring
Git-commit: bd77f6b1d7104cf6451399a7c67d08afecb9a7c7
Patch-mainline: v5.17-rc1
References: bsc#1206451

The DMA buffers of dbring which is used for spectral/cfr
starts at certain offset from original kmalloc() returned buffer.
This is not cache line aligned.
And also driver tries to access the data that is immediately before
this offset address (i.e. buff->paddr) after doing dma map.
This will cause cache line sharing issues and data corruption,
if CPU happen to write back cache after HW has dma'ed the data.

Fix this by mapping a cache line aligned buffer to dma.

Tested on: IPQ8074 hw2.0 AHB WLAN.HK.2.5.0.1-01100-QCAHKSWPL_SILICONZ-1

Signed-off-by: Rameshkumar Sundaram <quic_ramess@quicinc.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1635831693-15962-1-git-send-email-quic_ramess@quicinc.com
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/wireless/ath/ath11k/dbring.c | 16 ++++++++++++----
 drivers/net/wireless/ath/ath11k/dbring.h |  2 +-
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/dbring.c b/drivers/net/wireless/ath/ath11k/dbring.c
index fd98ba5b1130..de220a10bce3 100644
--- a/drivers/net/wireless/ath/ath11k/dbring.c
+++ b/drivers/net/wireless/ath/ath11k/dbring.c
@@ -87,17 +87,23 @@ static int ath11k_dbring_fill_bufs(struct ath11k *ar,
 	req_entries = min(num_free, ring->bufs_max);
 	num_remain = req_entries;
 	align = ring->buf_align;
-	size = sizeof(*buff) + ring->buf_sz + align - 1;
+	size = ring->buf_sz + align - 1;
 
 	while (num_remain > 0) {
-		buff = kzalloc(size, GFP_ATOMIC);
+		buff = kzalloc(sizeof(*buff), GFP_ATOMIC);
 		if (!buff)
 			break;
 
+		buff->payload = kzalloc(size, GFP_ATOMIC);
+		if (!buff->payload) {
+			kfree(buff);
+			break;
+		}
 		ret = ath11k_dbring_bufs_replenish(ar, ring, buff);
 		if (ret) {
 			ath11k_warn(ar->ab, "failed to replenish db ring num_remain %d req_ent %d\n",
 				    num_remain, req_entries);
+			kfree(buff->payload);
 			kfree(buff);
 			break;
 		}
@@ -282,7 +288,7 @@ int ath11k_dbring_buffer_release_event(struct ath11k_base *ab,
 
 	srng = &ab->hal.srng_list[ring->refill_srng.ring_id];
 	num_entry = ev->fixed.num_buf_release_entry;
-	size = sizeof(*buff) + ring->buf_sz + ring->buf_align - 1;
+	size = ring->buf_sz + ring->buf_align - 1;
 	num_buff_reaped = 0;
 
 	spin_lock_bh(&srng->lock);
@@ -319,7 +325,8 @@ int ath11k_dbring_buffer_release_event(struct ath11k_base *ab,
 			ring->handler(ar, &handler_data);
 		}
 
-		memset(buff, 0, size);
+		buff->paddr = 0;
+		memset(buff->payload, 0, size);
 		ath11k_dbring_bufs_replenish(ar, ring, buff);
 	}
 
@@ -346,6 +353,7 @@ void ath11k_dbring_buf_cleanup(struct ath11k *ar, struct ath11k_dbring *ring)
 		idr_remove(&ring->bufs_idr, buf_id);
 		dma_unmap_single(ar->ab->dev, buff->paddr,
 				 ring->buf_sz, DMA_FROM_DEVICE);
+		kfree(buff->payload);
 		kfree(buff);
 	}
 
diff --git a/drivers/net/wireless/ath/ath11k/dbring.h b/drivers/net/wireless/ath/ath11k/dbring.h
index f7fce9ef9c36..78a985faa0a1 100644
--- a/drivers/net/wireless/ath/ath11k/dbring.h
+++ b/drivers/net/wireless/ath/ath11k/dbring.h
@@ -13,7 +13,7 @@
 
 struct ath11k_dbring_element {
 	dma_addr_t paddr;
-	u8 payload[0];
+	u8 *payload;
 };
 
 struct ath11k_dbring_data {
-- 
2.35.3