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

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;
+			}
 		}
 	}
 

drivers/net/wireless/ath/ath11k/hal.c

@@ -626,15 +626,30 @@ u32 *ath11k_hal_srng_dst_peek(struct ath11k_base *ab, struct hal_srng *srng)
 	return NULL;
 }
 
+static u32 *ath11k_hal_srng_dst_peek_with_dma(struct ath11k_base *ab,
+					      struct hal_srng *srng, dma_addr_t *paddr)
+{
+	lockdep_assert_held(&srng->lock);
+
+	if (srng->u.dst_ring.tp != srng->u.dst_ring.cached_hp) {
+		*paddr = srng->ring_base_paddr +
+			  sizeof(*srng->ring_base_vaddr) * srng->u.dst_ring.tp;
+		return srng->ring_base_vaddr + srng->u.dst_ring.tp;
+	}
+
+	return NULL;
+}
+
 static void ath11k_hal_srng_prefetch_desc(struct ath11k_base *ab,
 					  struct hal_srng *srng)
 {
+	dma_addr_t desc_paddr;
 	u32 *desc;
 
 	/* prefetch only if desc is available */
-	desc = ath11k_hal_srng_dst_peek(ab, srng);
+	desc = ath11k_hal_srng_dst_peek_with_dma(ab, srng, &desc_paddr);
 	if (likely(desc)) {
-		dma_sync_single_for_cpu(ab->dev, virt_to_phys(desc),
+		dma_sync_single_for_cpu(ab->dev, desc_paddr,
 					(srng->entry_size * sizeof(u32)),
 					DMA_FROM_DEVICE);
 		prefetch(desc);