octeontx2-pf: map skb data as device writeable

Crypto hardware need write permission for in-place encrypt
or decrypt operation on skb-data to support IPsec crypto
offload. That patch uses skb_unshare to make skb data writeable
for ipsec crypto offload and map skb fragment memory as
device read-write.

Signed-off-by: Bharat Bhushan <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Bharat Bhushan

drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c

@@ -11,6 +11,7 @@
 #include <linux/bpf.h>
 #include <linux/bpf_trace.h>
 #include <net/ip6_checksum.h>
+#include <net/xfrm.h>
 
 #include "otx2_reg.h"
 #include "otx2_common.h"
@@ -83,10 +84,17 @@ static unsigned int frag_num(unsigned int i)
 static dma_addr_t otx2_dma_map_skb_frag(struct otx2_nic *pfvf,
 					struct sk_buff *skb, int seg, int *len)
 {
+	enum dma_data_direction dir = DMA_TO_DEVICE;
 	const skb_frag_t *frag;
 	struct page *page;
 	int offset;
 
+	/* Crypto hardware need write permission for ipsec crypto offload */
+	if (unlikely(xfrm_offload(skb))) {
+		dir = DMA_BIDIRECTIONAL;
+		skb = skb_unshare(skb, GFP_ATOMIC);
+	}
+
 	/* First segment is always skb->data */
 	if (!seg) {
 		page = virt_to_page(skb->data);
@@ -98,16 +106,22 @@ static dma_addr_t otx2_dma_map_skb_frag(struct otx2_nic *pfvf,
 		offset = skb_frag_off(frag);
 		*len = skb_frag_size(frag);
 	}
-	return otx2_dma_map_page(pfvf, page, offset, *len, DMA_TO_DEVICE);
+	return otx2_dma_map_page(pfvf, page, offset, *len, dir);
 }
 
 static void otx2_dma_unmap_skb_frags(struct otx2_nic *pfvf, struct sg_list *sg)
 {
+	enum dma_data_direction dir = DMA_TO_DEVICE;
+	struct sk_buff *skb = NULL;
 	int seg;
 
+	skb = (struct sk_buff *)sg->skb;
+	if (unlikely(xfrm_offload(skb)))
+		dir = DMA_BIDIRECTIONAL;
+
 	for (seg = 0; seg < sg->num_segs; seg++) {
 		otx2_dma_unmap_page(pfvf, sg->dma_addr[seg],
-				    sg->size[seg], DMA_TO_DEVICE);
+				    sg->size[seg], dir);
 	}
 	sg->num_segs = 0;
 }