ixgbe: fix panic while dumping packets on Tx hang with IOMMU

This patch resolves a "BUG: unable to handle kernel paging request at ..."
oops while dumping packet data. The issue occurs with IOMMU enabled due to
the address provided by phys_to_virt().

This patch makes use of skb->data on Tx and the virtual address of the pages
allocated for Rx.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -396,11 +396,10 @@ static void ixgbe_dump(struct ixgbe_adapter *adapter)
 				pr_cont("\n");
 
 			if (netif_msg_pktdata(adapter) &&
-			    dma_unmap_len(tx_buffer, len) != 0)
+			    tx_buffer->skb)
 				print_hex_dump(KERN_INFO, "",
 					DUMP_PREFIX_ADDRESS, 16, 1,
-					phys_to_virt(dma_unmap_addr(tx_buffer,
-								    dma)),
+					tx_buffer->skb->data,
 					dma_unmap_len(tx_buffer, len),
 					true);
 		}
@@ -474,10 +473,12 @@ rx_ring_summary:
 					(u64)rx_buffer_info->dma,
 					rx_buffer_info->skb);
 
-				if (netif_msg_pktdata(adapter)) {
+				if (netif_msg_pktdata(adapter) &&
+				    rx_buffer_info->dma) {
 					print_hex_dump(KERN_INFO, "",
 					   DUMP_PREFIX_ADDRESS, 16, 1,
-					   phys_to_virt(rx_buffer_info->dma),
+					   page_address(rx_buffer_info->page) +
+						    rx_buffer_info->page_offset,
 					   ixgbe_rx_bufsz(rx_ring), true);
 				}
 			}