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envelope-from=mjrosato@linux.ibm.com; helo=mx0a-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_H4=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 8/18/26 4:53 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 | 26 +++++++++++++++++++------- > 1 file changed, 19 insertions(+), 7 deletions(-) > > diff --git a/pc-bios/s390-ccw/virtio-net.c b/pc-bios/s390-ccw/virtio-net.c > index 0ee51653ab..3a9ae789cf 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" > > @@ -28,10 +29,15 @@ > #endif > > #define VIRTIO_NET_F_MAC_BIT (1 << 5) > +#define VIRTIO_NET_F_MRG_RXBUF_BIT (1 << 15) > > #define VQ_RX 0 /* Receive queue */ > #define VQ_TX 1 /* Transmit queue */ > > +/* Header sizes for different modes */ > +#define VIRTIO_NET_HDR_SIZE_LEGACY 10 /* Without num_buffers */ > +#define VIRTIO_NET_HDR_SIZE_V1 12 /* With num_buffers */ > + See my comment on Jared virtio-scsi series; you already have a structure defined for this, and this would just be a versioned variation on it; can you basically make a split structure and then calculate these constants using the sizeof() each struct, rather than using constant values here that circumstantially match the size of well-defined structures? FWIW, this looks to be exactly what the kernel does with virtio_net_hdr vs virtio_net_hdr_mrg_rxbuf in linux/uapi/linux/virtio_net.h (or qemu/include/standard-headers/linux/virtio_net.h) I am not suggesting we pull the standard-headers into s390-ccw, but I would recommend using that layout as a basis of the structures in this patch. Thanks, Matt