wifi: ath11k: fix IOMMU errors on buffer rings

virt_to_phys() doesn't work on systems with IOMMU enabled, which have
non-identity physical-to-IOVA mappings.  It leads to IO_PAGE_FAULTs like this:

[IO_PAGE_FAULT domain=0x0023 address=0x1cce00000 flags=0x0020]

And no association to the AP can be established.

This patch changes that to dma_map_single(), which works correctly. Even
virt_to_phys() documentation says device drivers should not use it:

    This function does not give bus mappings for DMA transfers. In
    almost all conceivable cases a device driver should not be using
    this function

Tested-on: QCN9074 hw1.0 PCI WLAN.HK.2.7.0.1-01744-QCAHKSWPL_SILICONZ-1

Signed-off-by: Zhenghao Gu <imguzh@gmail.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20231212031914.47339-1-imguzh@gmail.com

1 files changed, 17 insertions, 3 deletions

diff --git a/drivers/net/wireless/ath/ath11k/dp.c b/drivers/net/wireless/ath/ath11k/dp.c
index 8975dc57ad77..1a62407e5a9f 100644
--- a/drivers/net/wireless/ath/ath11k/dp.c
+++ b/drivers/net/wireless/ath/ath11k/dp.c
@@ -104,11 +104,14 @@ void ath11k_dp_srng_cleanup(struct ath11k_base *ab, struct dp_srng *ring)
 	if (!ring->vaddr_unaligned)
 		return;
 
-	if (ring->cached)
+	if (ring->cached) {
+		dma_unmap_single(ab->dev, ring->paddr_unaligned, ring->size,
+				 DMA_FROM_DEVICE);
 		kfree(ring->vaddr_unaligned);
-	else
+	} else {
 		dma_free_coherent(ab->dev, ring->size, ring->vaddr_unaligned,
 				  ring->paddr_unaligned);
+	}
 
 	ring->vaddr_unaligned = NULL;
 }
@@ -249,7 +252,18 @@ int ath11k_dp_srng_setup(struct ath11k_base *ab, struct dp_srng *ring,
 
 		if (cached) {
 			ring->vaddr_unaligned = kzalloc(ring->size, GFP_KERNEL);
-			ring->paddr_unaligned = virt_to_phys(ring->vaddr_unaligned);
+			if (!ring->vaddr_unaligned)
+				return -ENOMEM;
+
+			ring->paddr_unaligned = dma_map_single(ab->dev,
+							       ring->vaddr_unaligned,
+							       ring->size,
+							       DMA_FROM_DEVICE);
+			if (dma_mapping_error(ab->dev, ring->paddr_unaligned)) {
+				kfree(ring->vaddr_unaligned);
+				ring->vaddr_unaligned = NULL;
+				return -ENOMEM;
+			}
 		}
 	}