git: dc00f118405e - main - Revert "virtio_net: Use bus_dma for rxq/txq buffers"
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Date: Tue, 05 May 2026 09:33:17 UTC
The branch main has been updated by andrew:
URL: https://cgit.FreeBSD.org/src/commit/?id=dc00f118405e8638ceb13b288e14164a8a9ba669
commit dc00f118405e8638ceb13b288e14164a8a9ba669
Author: Andrew Turner <andrew@FreeBSD.org>
AuthorDate: 2026-05-05 09:17:51 +0000
Commit: Andrew Turner <andrew@FreeBSD.org>
CommitDate: 2026-05-05 09:18:14 +0000
Revert "virtio_net: Use bus_dma for rxq/txq buffers"
This reverts commit c16c95192f01237a876eb7bc336e3bbda9310171.
Revert until we can fix reported issues
---
sys/dev/virtio/network/if_vtnet.c | 275 +++--------------------------------
sys/dev/virtio/network/if_vtnetvar.h | 10 --
2 files changed, 17 insertions(+), 268 deletions(-)
diff --git a/sys/dev/virtio/network/if_vtnet.c b/sys/dev/virtio/network/if_vtnet.c
index e88602a44664..ef01833b9e03 100644
--- a/sys/dev/virtio/network/if_vtnet.c
+++ b/sys/dev/virtio/network/if_vtnet.c
@@ -96,17 +96,6 @@
#define VTNET_ETHER_ALIGN ETHER_ALIGN
#endif
-/*
- * Worst case offset to ensure header doesn't share any cache lines with
- * payload.
- */
-#define VTNET_RX_BUFFER_HEADER_OFFSET 128
-
-struct vtnet_rx_buffer_header {
- bus_addr_t addr;
- bus_dmamap_t dmap;
-};
-
static int vtnet_modevent(module_t, int, void *);
static int vtnet_probe(device_t);
@@ -395,17 +384,6 @@ MODULE_DEPEND(vtnet, netmap, 1, 1, 1);
VIRTIO_SIMPLE_PNPINFO(vtnet, VIRTIO_ID_NETWORK, "VirtIO Networking Adapter");
-static struct vtnet_rx_buffer_header *
-vtnet_mbuf_to_rx_buffer_header(struct vtnet_softc *sc, struct mbuf *m)
-{
- if (VTNET_ETHER_ALIGN != 0 && sc->vtnet_hdr_size % 4 == 0)
- return (struct vtnet_rx_buffer_header *)((uintptr_t)m->m_data -
- VTNET_RX_BUFFER_HEADER_OFFSET - VTNET_ETHER_ALIGN);
- else
- return (struct vtnet_rx_buffer_header *)((uintptr_t)m->m_data -
- VTNET_RX_BUFFER_HEADER_OFFSET);
-}
-
static int
vtnet_modevent(module_t mod __unused, int type, void *unused __unused)
{
@@ -479,60 +457,6 @@ vtnet_attach(device_t dev)
goto fail;
}
- mtx_init(&sc->vtnet_rx_mtx, device_get_nameunit(dev),
- "VirtIO Net RX lock", MTX_DEF);
-
- error = bus_dma_tag_create(
- bus_get_dma_tag(dev), /* parent */
- sizeof(uint16_t), /* alignment */
- 0, /* boundary */
- BUS_SPACE_MAXADDR, /* lowaddr */
- BUS_SPACE_MAXADDR, /* highaddr */
- NULL, NULL, /* filter, filterarg */
- MJUM9BYTES, /* max request size */
- 1, /* max # segments */
- MJUM9BYTES, /* maxsegsize - worst case */
- BUS_DMA_COHERENT, /* flags */
- busdma_lock_mutex, /* lockfunc */
- &sc->vtnet_rx_mtx, /* lockarg */
- &sc->vtnet_rx_dmat);
- if (error) {
- device_printf(dev, "cannot create bus_dma_tag\n");
- goto fail;
- }
-
- mtx_init(&sc->vtnet_tx_mtx, device_get_nameunit(dev),
- "VirtIO Net TX lock", MTX_DEF);
-
- error = bus_dma_tag_create(
- bus_get_dma_tag(dev), /* parent */
- sizeof(uint16_t), /* alignment */
- 0, /* boundary */
- BUS_SPACE_MAXADDR, /* lowaddr */
- BUS_SPACE_MAXADDR, /* highaddr */
- NULL, NULL, /* filter, filterarg */
- sc->vtnet_tx_nsegs * MJUM9BYTES, /* max request size */
- sc->vtnet_tx_nsegs, /* max # segments */
- MJUM9BYTES, /* maxsegsize */
- BUS_DMA_COHERENT, /* flags */
- busdma_lock_mutex, /* lockfunc */
- &sc->vtnet_tx_mtx, /* lockarg */
- &sc->vtnet_tx_dmat);
- if (error) {
- device_printf(dev, "cannot create bus_dma_tag\n");
- goto fail;
- }
-
-#ifdef __powerpc__
- /*
- * Virtio uses physical addresses rather than bus addresses, so we
- * need to ask busdma to skip the iommu physical->bus mapping. At
- * present, this is only a thing on the powerpc architectures.
- */
- bus_dma_tag_set_iommu(sc->vtnet_rx_dmat, NULL, NULL);
- bus_dma_tag_set_iommu(sc->vtnet_tx_dmat, NULL, NULL);
-#endif
-
error = vtnet_alloc_rx_filters(sc);
if (error) {
device_printf(dev, "cannot allocate Rx filters\n");
@@ -1621,11 +1545,6 @@ static struct mbuf *
vtnet_rx_alloc_buf(struct vtnet_softc *sc, int nbufs, struct mbuf **m_tailp)
{
struct mbuf *m_head, *m_tail, *m;
- struct vtnet_rx_buffer_header *vthdr;
- bus_dma_segment_t segs[1];
- bus_dmamap_t dmap;
- int nsegs;
- int err;
int i, size;
m_head = NULL;
@@ -1643,43 +1562,13 @@ vtnet_rx_alloc_buf(struct vtnet_softc *sc, int nbufs, struct mbuf **m_tailp)
}
m->m_len = size;
- vthdr = (struct vtnet_rx_buffer_header *)m->m_data;
-
- /* Reserve space for header */
- m_adj(m, VTNET_RX_BUFFER_HEADER_OFFSET);
-
/*
* Need to offset the mbuf if the header we're going to add
* will misalign.
*/
- if (VTNET_ETHER_ALIGN != 0 && sc->vtnet_hdr_size % 4 == 0)
+ if (VTNET_ETHER_ALIGN != 0 && sc->vtnet_hdr_size % 4 == 0) {
m_adj(m, VTNET_ETHER_ALIGN);
-
- err = bus_dmamap_create(sc->vtnet_rx_dmat, 0, &dmap);
- if (err) {
- printf("Failed to create dmamap, err :%d\n",
- err);
- m_freem(m);
- return (NULL);
}
-
- nsegs = 0;
- err = bus_dmamap_load_mbuf_sg(sc->vtnet_rx_dmat, dmap, m, segs,
- &nsegs, BUS_DMA_NOWAIT);
- if (err != 0) {
- printf("Failed to map mbuf into DMA visible memory, err: %d\n",
- err);
- m_freem(m);
- bus_dmamap_destroy(sc->vtnet_rx_dmat, dmap);
- return (NULL);
- }
- KASSERT(nsegs == 1,
- ("%s: unexpected number of DMA segments for rx buffer: %d",
- __func__, nsegs));
-
- vthdr->addr = segs[0].ds_addr;
- vthdr->dmap = dmap;
-
if (m_head != NULL) {
m_tail->m_next = m;
m_tail = m;
@@ -1705,7 +1594,7 @@ vtnet_rxq_replace_lro_nomrg_buf(struct vtnet_rxq *rxq, struct mbuf *m0,
int len, clustersz, nreplace, error;
sc = rxq->vtnrx_sc;
- clustersz = sc->vtnet_rx_clustersz - VTNET_RX_BUFFER_HEADER_OFFSET;
+ clustersz = sc->vtnet_rx_clustersz;
/*
* Need to offset the mbuf if the header we're going to add will
* misalign, account for that here.
@@ -1820,12 +1709,9 @@ vtnet_rxq_replace_buf(struct vtnet_rxq *rxq, struct mbuf *m, int len)
static int
vtnet_rxq_enqueue_buf(struct vtnet_rxq *rxq, struct mbuf *m)
{
- struct vtnet_rx_buffer_header *hdr;
struct vtnet_softc *sc;
struct sglist *sg;
int header_inlined, error;
- bus_addr_t paddr;
- struct mbuf *mp;
sc = rxq->vtnrx_sc;
sg = rxq->vtnrx_sg;
@@ -1838,38 +1724,28 @@ vtnet_rxq_enqueue_buf(struct vtnet_rxq *rxq, struct mbuf *m)
header_inlined = vtnet_modern(sc) ||
(sc->vtnet_flags & VTNET_FLAG_MRG_RXBUFS) != 0; /* TODO: ANY_LAYOUT */
- hdr = vtnet_mbuf_to_rx_buffer_header(sc, m);
- paddr = hdr->addr;
-
/*
* Note: The mbuf has been already adjusted when we allocate it if we
* have to do strict alignment.
*/
- if (header_inlined) {
- error = sglist_append_phys(sg, paddr, m->m_len);
- } else {
+ if (header_inlined)
+ error = sglist_append_mbuf(sg, m);
+ else {
+ struct vtnet_rx_header *rxhdr =
+ mtod(m, struct vtnet_rx_header *);
MPASS(sc->vtnet_hdr_size == sizeof(struct virtio_net_hdr));
/* Append the header and remaining mbuf data. */
- error = sglist_append_phys(sg, paddr, sc->vtnet_hdr_size);
+ error = sglist_append(sg, &rxhdr->vrh_hdr, sc->vtnet_hdr_size);
if (error)
return (error);
- error = sglist_append_phys(sg,
- paddr + sizeof(struct vtnet_rx_header),
+ error = sglist_append(sg, &rxhdr[1],
m->m_len - sizeof(struct vtnet_rx_header));
if (error)
return (error);
- mp = m->m_next;
- while (mp) {
- hdr = vtnet_mbuf_to_rx_buffer_header(sc, mp);
- paddr = hdr->addr;
- error = sglist_append_phys(sg, paddr, mp->m_len);
- if (error)
- return (error);
-
- mp = mp->m_next;
- }
+ if (m->m_next != NULL)
+ error = sglist_append_mbuf(sg, m->m_next);
}
if (error)
@@ -2055,7 +1931,6 @@ vtnet_rxq_merged_eof(struct vtnet_rxq *rxq, struct mbuf *m_head, int nbufs)
m_tail = m_head;
while (--nbufs > 0) {
- struct vtnet_rx_buffer_header *vthdr;
struct mbuf *m;
uint32_t len;
@@ -2065,10 +1940,6 @@ vtnet_rxq_merged_eof(struct vtnet_rxq *rxq, struct mbuf *m_head, int nbufs)
goto fail;
}
- vthdr = vtnet_mbuf_to_rx_buffer_header(sc, m);
- bus_dmamap_sync(sc->vtnet_rx_dmat, vthdr->dmap,
- BUS_DMASYNC_POSTREAD);
-
if (vtnet_rxq_new_buf(rxq) != 0) {
rxq->vtnrx_stats.vrxs_iqdrops++;
vtnet_rxq_discard_buf(rxq, m);
@@ -2189,7 +2060,6 @@ static int
vtnet_rxq_eof(struct vtnet_rxq *rxq)
{
struct virtio_net_hdr lhdr, *hdr;
- struct vtnet_rx_buffer_header *vthdr;
struct vtnet_softc *sc;
if_t ifp;
struct virtqueue *vq;
@@ -2205,31 +2075,14 @@ vtnet_rxq_eof(struct vtnet_rxq *rxq)
CURVNET_SET(if_getvnet(ifp));
while (count-- > 0) {
- struct mbuf *m, *mp;
+ struct mbuf *m;
uint32_t len, nbufs, adjsz;
- uint32_t synced;
m = virtqueue_dequeue(vq, &len);
if (m == NULL)
break;
deq++;
- mp = m;
-
- /*
- * Sync all mbufs in this packet. There will only be a single
- * mbuf unless LRO is in use.
- */
- synced = 0;
- while (mp && synced < len) {
- vthdr = vtnet_mbuf_to_rx_buffer_header(sc, mp);
- bus_dmamap_sync(sc->vtnet_rx_dmat, vthdr->dmap,
- BUS_DMASYNC_POSTREAD);
-
- synced += mp->m_len;
- mp = mp->m_next;
- }
-
if (len < sc->vtnet_hdr_size + ETHER_HDR_LEN) {
rxq->vtnrx_stats.vrxs_ierrors++;
vtnet_rxq_discard_buf(rxq, m);
@@ -2489,14 +2342,6 @@ vtnet_txq_free_mbufs(struct vtnet_txq *txq)
while ((txhdr = virtqueue_drain(vq, &last)) != NULL) {
if (kring == NULL) {
- bus_dmamap_unload(txq->vtntx_sc->vtnet_tx_dmat,
- txhdr->dmap);
- bus_dmamap_destroy(txq->vtntx_sc->vtnet_tx_dmat,
- txhdr->dmap);
- bus_dmamap_unload(txq->vtntx_sc->vtnet_tx_dmat,
- txhdr->hdr_dmap);
- bus_dmamap_destroy(txq->vtntx_sc->vtnet_tx_dmat,
- txhdr->hdr_dmap);
m_freem(txhdr->vth_mbuf);
uma_zfree(vtnet_tx_header_zone, txhdr);
}
@@ -2666,36 +2511,15 @@ drop:
return (NULL);
}
-static void
-vtnet_txq_enqueue_callback(void *arg, bus_dma_segment_t *segs,
- int nsegs, int error)
-{
- vm_paddr_t *hdr_paddr;
-
- if (error != 0)
- return;
-
- KASSERT(nsegs == 1, ("%s: %d segments returned!", __func__, nsegs));
-
- hdr_paddr = (vm_paddr_t *)arg;
- *hdr_paddr = segs[0].ds_addr;
-}
-
static int
vtnet_txq_enqueue_buf(struct vtnet_txq *txq, struct mbuf **m_head,
struct vtnet_tx_header *txhdr)
{
- bus_dma_segment_t segs[VTNET_TX_SEGS_MAX];
- int nsegs;
struct vtnet_softc *sc;
struct virtqueue *vq;
struct sglist *sg;
struct mbuf *m;
int error;
- vm_paddr_t hdr_paddr;
- bus_dmamap_t hdr_dmap;
- bus_dmamap_t dmap;
- int i;
sc = txq->vtntx_sc;
vq = txq->vtntx_vq;
@@ -2703,55 +2527,15 @@ vtnet_txq_enqueue_buf(struct vtnet_txq *txq, struct mbuf **m_head,
m = *m_head;
sglist_reset(sg);
-
- error = bus_dmamap_create(sc->vtnet_tx_dmat, 0, &hdr_dmap);
- if (error)
- goto fail;
-
- error = bus_dmamap_load(sc->vtnet_tx_dmat, hdr_dmap, &txhdr->vth_uhdr,
- sc->vtnet_hdr_size, vtnet_txq_enqueue_callback, &hdr_paddr,
- BUS_DMA_NOWAIT);
- if (error)
- goto fail_hdr_dmamap_destroy;
-
- error = sglist_append_phys(sg, hdr_paddr, sc->vtnet_hdr_size);
+ error = sglist_append(sg, &txhdr->vth_uhdr, sc->vtnet_hdr_size);
if (error != 0 || sg->sg_nseg != 1) {
KASSERT(0, ("%s: cannot add header to sglist error %d nseg %d",
__func__, error, sg->sg_nseg));
- goto fail_hdr_dmamap_unload;
+ goto fail;
}
- bus_dmamap_sync(sc->vtnet_tx_dmat, hdr_dmap, BUS_DMASYNC_PREWRITE);
-
- error = bus_dmamap_create(sc->vtnet_tx_dmat, 0, &dmap);
- if (error)
- goto fail_hdr_dmamap_unload;
-
- nsegs = 0;
- error = bus_dmamap_load_mbuf_sg(sc->vtnet_tx_dmat, dmap, m, segs,
- &nsegs, BUS_DMA_NOWAIT);
- if (error != 0)
- goto fail_dmamap_destroy;
- KASSERT(nsegs <= sc->vtnet_tx_nsegs,
- ("%s: unexpected number of DMA segments for tx buffer: %d (max %d)",
- __func__, nsegs, sc->vtnet_tx_nsegs));
-
- bus_dmamap_sync(sc->vtnet_tx_dmat, dmap, BUS_DMASYNC_PREWRITE);
-
- for (i = 0; i < nsegs && !error; i++)
- error = sglist_append_phys(sg, segs[i].ds_addr, segs[i].ds_len);
-
+ error = sglist_append_mbuf(sg, m);
if (error) {
- sglist_reset(sg);
- bus_dmamap_unload(sc->vtnet_tx_dmat, dmap);
-
- error = sglist_append_phys(sg, hdr_paddr, sc->vtnet_hdr_size);
- if (error != 0 || sg->sg_nseg != 1) {
- KASSERT(0, ("%s: cannot add header to sglist error %d nseg %d",
- __func__, error, sg->sg_nseg));
- goto fail_dmamap_destroy;
- }
-
m = m_defrag(m, M_NOWAIT);
if (m == NULL) {
sc->vtnet_stats.tx_defrag_failed++;
@@ -2761,41 +2545,16 @@ vtnet_txq_enqueue_buf(struct vtnet_txq *txq, struct mbuf **m_head,
*m_head = m;
sc->vtnet_stats.tx_defragged++;
- nsegs = 0;
- error = bus_dmamap_load_mbuf_sg(sc->vtnet_tx_dmat, dmap, m,
- segs, &nsegs, BUS_DMA_NOWAIT);
- if (error != 0)
- goto fail_dmamap_destroy;
- KASSERT(nsegs <= sc->vtnet_tx_nsegs,
- ("%s: unexpected number of DMA segments for tx buffer: %d (max %d)",
- __func__, nsegs, sc->vtnet_tx_nsegs));
-
- bus_dmamap_sync(sc->vtnet_tx_dmat, dmap, BUS_DMASYNC_PREWRITE);
-
- for (i = 0; i < nsegs && !error; i++)
- error = sglist_append_phys(sg, segs[i].ds_addr,
- segs[i].ds_len);
-
+ error = sglist_append_mbuf(sg, m);
if (error)
- goto fail_dmamap_unload;
+ goto fail;
}
txhdr->vth_mbuf = m;
- txhdr->dmap = dmap;
- txhdr->hdr_dmap = hdr_dmap;
-
error = virtqueue_enqueue(vq, txhdr, sg, sg->sg_nseg, 0);
return (error);
-fail_dmamap_unload:
- bus_dmamap_unload(sc->vtnet_tx_dmat, dmap);
-fail_dmamap_destroy:
- bus_dmamap_destroy(sc->vtnet_tx_dmat, dmap);
-fail_hdr_dmamap_unload:
- bus_dmamap_unload(sc->vtnet_tx_dmat, hdr_dmap);
-fail_hdr_dmamap_destroy:
- bus_dmamap_destroy(sc->vtnet_tx_dmat, hdr_dmap);
fail:
m_freem(*m_head);
*m_head = NULL;
diff --git a/sys/dev/virtio/network/if_vtnetvar.h b/sys/dev/virtio/network/if_vtnetvar.h
index 6cafe827d733..eb5e6784b07f 100644
--- a/sys/dev/virtio/network/if_vtnetvar.h
+++ b/sys/dev/virtio/network/if_vtnetvar.h
@@ -190,12 +190,6 @@ struct vtnet_softc {
struct mtx vtnet_mtx;
char vtnet_mtx_name[16];
uint8_t vtnet_hwaddr[ETHER_ADDR_LEN];
-
- bus_dma_tag_t vtnet_rx_dmat;
- struct mtx vtnet_rx_mtx;
-
- bus_dma_tag_t vtnet_tx_dmat;
- struct mtx vtnet_tx_mtx;
};
/* vtnet flag descriptions for use with printf(9) %b identifier. */
#define VTNET_FLAGS_BITS \
@@ -279,10 +273,6 @@ struct vtnet_tx_header {
} vth_uhdr;
struct mbuf *vth_mbuf;
-
- bus_dmamap_t dmap;
-
- bus_dmamap_t hdr_dmap;
};
/*