Revert "virtio_net: rx remove premapped failover code"

This reverts commit defd28aa5acb0fd7c15adc6bc40a8ac277d04dea.

Recover the code to disable premapped mode.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Takero Funaki <flintglass@gmail.com>
Link: https://patch.msgid.link/20240906123137.108741-2-xuanzhuo@linux.alibaba.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index c6af189480929a8ccea4090d7f343380f29b730c..6fa8aab18484e67cbd10e9dda4103d5810e67f44 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -356,6 +356,9 @@ struct receive_queue {
        struct xdp_rxq_info xsk_rxq_info;
 
        struct xdp_buff **xsk_buffs;
+
+       /* Do dma by self */
+       bool do_dma;
 };
 
 /* This structure can contain rss message with maximum settings for indirection table and keysize
@@ -885,7 +888,7 @@ static void *virtnet_rq_get_buf(struct receive_queue *rq, u32 *len, void **ctx)
        void *buf;
 
        buf = virtqueue_get_buf_ctx(rq->vq, len, ctx);
-       if (buf)
+       if (buf && rq->do_dma)
                virtnet_rq_unmap(rq, buf, *len);
 
        return buf;
@@ -898,6 +901,11 @@ static void virtnet_rq_init_one_sg(struct receive_queue *rq, void *buf, u32 len)
        u32 offset;
        void *head;
 
+       if (!rq->do_dma) {
+               sg_init_one(rq->sg, buf, len);
+               return;
+       }
+
        head = page_address(rq->alloc_frag.page);
 
        offset = buf - head;
@@ -923,42 +931,44 @@ static void *virtnet_rq_alloc(struct receive_queue *rq, u32 size, gfp_t gfp)
 
        head = page_address(alloc_frag->page);
 
-       dma = head;
+       if (rq->do_dma) {
+               dma = head;
+
+               /* new pages */
+               if (!alloc_frag->offset) {
+                       if (rq->last_dma) {
+                               /* Now, the new page is allocated, the last dma
+                                * will not be used. So the dma can be unmapped
+                                * if the ref is 0.
+                                */
+                               virtnet_rq_unmap(rq, rq->last_dma, 0);
+                               rq->last_dma = NULL;
+                       }
 
-       /* new pages */
-       if (!alloc_frag->offset) {
-               if (rq->last_dma) {
-                       /* Now, the new page is allocated, the last dma
-                        * will not be used. So the dma can be unmapped
-                        * if the ref is 0.
-                        */
-                       virtnet_rq_unmap(rq, rq->last_dma, 0);
-                       rq->last_dma = NULL;
-               }
+                       dma->len = alloc_frag->size - sizeof(*dma);
 
-               dma->len = alloc_frag->size - sizeof(*dma);
+                       addr = virtqueue_dma_map_single_attrs(rq->vq, dma + 1,
+                                                             dma->len, DMA_FROM_DEVICE, 0);
+                       if (virtqueue_dma_mapping_error(rq->vq, addr))
+                               return NULL;
 
-               addr = virtqueue_dma_map_single_attrs(rq->vq, dma + 1,
-                                                     dma->len, DMA_FROM_DEVICE, 0);
-               if (virtqueue_dma_mapping_error(rq->vq, addr))
-                       return NULL;
+                       dma->addr = addr;
+                       dma->need_sync = virtqueue_dma_need_sync(rq->vq, addr);
 
-               dma->addr = addr;
-               dma->need_sync = virtqueue_dma_need_sync(rq->vq, addr);
+                       /* Add a reference to dma to prevent the entire dma from
+                        * being released during error handling. This reference
+                        * will be freed after the pages are no longer used.
+                        */
+                       get_page(alloc_frag->page);
+                       dma->ref = 1;
+                       alloc_frag->offset = sizeof(*dma);
 
-               /* Add a reference to dma to prevent the entire dma from
-                * being released during error handling. This reference
-                * will be freed after the pages are no longer used.
-                */
-               get_page(alloc_frag->page);
-               dma->ref = 1;
-               alloc_frag->offset = sizeof(*dma);
+                       rq->last_dma = dma;
+               }
 
-               rq->last_dma = dma;
+               ++dma->ref;
        }
 
-       ++dma->ref;
-
        buf = head + alloc_frag->offset;
 
        get_page(alloc_frag->page);
@@ -975,9 +985,12 @@ static void virtnet_rq_set_premapped(struct virtnet_info *vi)
        if (!vi->mergeable_rx_bufs && vi->big_packets)
                return;
 
-       for (i = 0; i < vi->max_queue_pairs; i++)
-               /* error should never happen */
-               BUG_ON(virtqueue_set_dma_premapped(vi->rq[i].vq));
+       for (i = 0; i < vi->max_queue_pairs; i++) {
+               if (virtqueue_set_dma_premapped(vi->rq[i].vq))
+                       continue;
+
+               vi->rq[i].do_dma = true;
+       }
 }
 
 static void virtnet_rq_unmap_free_buf(struct virtqueue *vq, void *buf)
@@ -2430,7 +2443,8 @@ static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue *rq,
 
        err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
        if (err < 0) {
-               virtnet_rq_unmap(rq, buf, 0);
+               if (rq->do_dma)
+                       virtnet_rq_unmap(rq, buf, 0);
                put_page(virt_to_head_page(buf));
        }
 
@@ -2544,7 +2558,8 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi,
        ctx = mergeable_len_to_ctx(len + room, headroom);
        err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
        if (err < 0) {
-               virtnet_rq_unmap(rq, buf, 0);
+               if (rq->do_dma)
+                       virtnet_rq_unmap(rq, buf, 0);
                put_page(virt_to_head_page(buf));
        }
 
@@ -5892,7 +5907,7 @@ static void free_receive_page_frags(struct virtnet_info *vi)
        int i;
        for (i = 0; i < vi->max_queue_pairs; i++)
                if (vi->rq[i].alloc_frag.page) {
-                       if (vi->rq[i].last_dma)
+                       if (vi->rq[i].do_dma && vi->rq[i].last_dma)
                                virtnet_rq_unmap(&vi->rq[i], vi->rq[i].last_dma, 0);
                        put_page(vi->rq[i].alloc_frag.page);
                }