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envelope-from=jrossi@linux.ibm.com; helo=mx0b-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 9/3/26 12:24 PM, Zhuoying Cai wrote: > The virtio-net device used a fixed header size that did not account for > the num_buffers field used in VirtIO 1.0 or for the mergeable receive > buffers feature. > > Use dynamic header sizing: 10 bytes for legacy mode and 12 bytes for > VirtIO 1.0 or when VIRTIO_NET_F_MRG_RXBUF is enabled. This ensures > correct packet handling across different VirtIO configurations. > > Signed-off-by: Zhuoying Cai > --- > pc-bios/s390-ccw/virtio-net.c | 30 ++++++++++++++++++++++++------ > 1 file changed, 24 insertions(+), 6 deletions(-) > > diff --git a/pc-bios/s390-ccw/virtio-net.c b/pc-bios/s390-ccw/virtio-net.c > index f58f7ffc55..afa728bc32 100644 > --- a/pc-bios/s390-ccw/virtio-net.c > +++ b/pc-bios/s390-ccw/virtio-net.c > @@ -20,6 +20,7 @@ > #include "s390-ccw.h" > #include "virtio.h" > #include "virtio-ccw.h" > +#include "virtio-pci.h" > #include "s390-time.h" > #include "helper.h" > > @@ -28,6 +29,7 @@ > #endif > > #define VIRTIO_NET_F_MAC_BIT (1 << 5) > +#define VIRTIO_NET_F_MRG_RXBUF_BIT (1 << 15) We define this new feature bit, but it looks like we never set it. The existing virtio_net_init() code has only: vdev->guest_features[0] = VIRTIO_NET_F_MAC_BIT; Should it be updated to VIRTIO_NET_F_MAC_BIT | VIRTIO_NET_F_MRG_RXBUF_BIT? Is the new feature bit something we want to unconditionally request, only request for PCI, or do we simply not care about it? > > #define VQ_RX 0 /* Receive queue */ > #define VQ_TX 1 /* Transmit queue */ > @@ -43,7 +45,18 @@ struct VirtioNetHdr { > }; > typedef struct VirtioNetHdr VirtioNetHdr; > > +struct VirtioNetHdrMrgRxbuf { > + struct VirtioNetHdr hdr; > + uint16_t num_buffers; /* Only with VIRTIO_NET_F_MRG_RXBUF or VIRTIO1 */ > +}; > +typedef struct VirtioNetHdrMrgRxbuf VirtioNetHdrMrgRxbuf; > + > +/* Header sizes for different modes */ > +#define VIRTIO_NET_HDR_SIZE_LEGACY sizeof(VirtioNetHdr) > +#define VIRTIO_NET_HDR_SIZE_V1 sizeof(VirtioNetHdrMrgRxbuf) > + > static uint16_t rx_last_idx; /* Last index in receive queue "used" ring */ > +static int virtio_net_hdr_size; > > int virtio_net_init(void *mac_addr) > { > @@ -62,12 +75,17 @@ int virtio_net_init(void *mac_addr) > return -1; > } > > + virtio_net_hdr_size = ((vdev->guest_features[1] & VIRTIO_F_VERSION_1) || > + (vdev->guest_features[0] & VIRTIO_NET_F_MRG_RXBUF_BIT)) Because we do not set VIRTIO_NET_F_MRG_RXBUF in net_init(), only the first half of this check can ever return true. Maybe that is correct, but in that case we can simplify this to just vdev->guest_features[1] & VIRTIO_F_VERSION_1, right? Regards, Jared Rossi > + ? VIRTIO_NET_HDR_SIZE_V1 > + : VIRTIO_NET_HDR_SIZE_LEGACY; > + > memcpy(mac_addr, vdev->config.net.mac, ETH_ALEN); > > for (i = 0; i < 64; i++) { > - buf = malloc(ETH_MTU_SIZE + sizeof(VirtioNetHdr)); > + buf = malloc(ETH_MTU_SIZE + virtio_net_hdr_size); > IPL_assert(buf != NULL, "Can not allocate memory for receive buffers"); > - vring_send_buf(rxvq, buf, ETH_MTU_SIZE + sizeof(VirtioNetHdr), > + vring_send_buf(rxvq, buf, ETH_MTU_SIZE + virtio_net_hdr_size, > VRING_DESC_F_WRITE); > } > vring_notify(rxvq); > @@ -77,14 +95,14 @@ int virtio_net_init(void *mac_addr) > > int send(int fd, const void *buf, int len, int flags) > { > - VirtioNetHdr tx_hdr; > + VirtioNetHdrMrgRxbuf tx_hdr; > VDev *vdev = virtio_get_device(); > VRing *txvq = &vdev->vrings[VQ_TX]; > > /* Set up header - we do not use anything special, so simply clear it */ > memset(&tx_hdr, 0, sizeof(tx_hdr)); > > - vring_send_buf(txvq, &tx_hdr, sizeof(tx_hdr), VRING_DESC_F_NEXT); > + vring_send_buf(txvq, &tx_hdr, virtio_net_hdr_size, VRING_DESC_F_NEXT); > vring_send_buf(txvq, (void *)buf, len, VRING_HIDDEN_IS_CHAIN); > while (!vr_poll(txvq)) { > yield(); > @@ -108,13 +126,13 @@ int recv(int fd, void *buf, int maxlen, int flags) > return 0; > } > > - len = rxvq->used->ring[rx_last_idx % rxvq->num].len - sizeof(VirtioNetHdr); > + len = rxvq->used->ring[rx_last_idx % rxvq->num].len - virtio_net_hdr_size; > if (len > maxlen) { > puts("virtio-net: Receive buffer too small"); > len = maxlen; > } > id = rxvq->used->ring[rx_last_idx % rxvq->num].id % rxvq->num; > - pkt = (uint8_t *)(rxvq->desc[id].addr + sizeof(VirtioNetHdr)); > + pkt = (uint8_t *)(rxvq->desc[id].addr + virtio_net_hdr_size); > > #if DEBUG_VIRTIO_NET /* Dump packet */ > int i;