From 79b6a98587c65c8b8fdde8eb778396f1fc98a852 Mon Sep 17 00:00:00 2001 From: William Hooper Date: Sat, 6 Jan 2024 14:35:46 -0800 Subject: [PATCH] net/vmnet: Pad short Ethernet frames MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit At least on macOS 12.7.2, vmnet doesn't pad Ethernet frames, such as the host's ARP replies, to the minimum size (60 bytes before the frame check sequence) defined in IEEE Std 802.3-2022, so guests' Ethernet device drivers may drop them with "frame too short" errors. This patch calls eth_pad_short_frame() to add padding, as in net/tap.c and net/slirp.c. Thanks to Bin Meng, Philippe Mathieu-Daudé, and Phil Dennis-Jordan for reviewing earlier versions. Signed-off-by: William Hooper Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2058 Reviewed-by: Phil Dennis-Jordan Message-ID: <20241102205653.30476-1-wsh@wshooper.org> Signed-off-by: Philippe Mathieu-Daudé --- net/vmnet-common.m | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) diff --git a/net/vmnet-common.m b/net/vmnet-common.m index dba5b5bab1..54d900ba67 100644 --- a/net/vmnet-common.m +++ b/net/vmnet-common.m @@ -18,6 +18,7 @@ #include "qemu/error-report.h" #include "qapi/error.h" #include "system/runstate.h" +#include "net/eth.h" #include #include @@ -147,10 +148,26 @@ static int vmnet_read_packets(VmnetState *s) */ static void vmnet_write_packets_to_qemu(VmnetState *s) { + uint8_t *pkt; + size_t pktsz; + uint8_t min_pkt[ETH_ZLEN]; + size_t min_pktsz; + ssize_t size; + while (s->packets_send_current_pos < s->packets_send_end_pos) { - ssize_t size = qemu_send_packet_async(&s->nc, - s->iov_buf[s->packets_send_current_pos].iov_base, - s->packets_buf[s->packets_send_current_pos].vm_pkt_size, + pkt = s->iov_buf[s->packets_send_current_pos].iov_base; + pktsz = s->packets_buf[s->packets_send_current_pos].vm_pkt_size; + + if (net_peer_needs_padding(&s->nc)) { + min_pktsz = sizeof(min_pkt); + + if (eth_pad_short_frame(min_pkt, &min_pktsz, pkt, pktsz)) { + pkt = min_pkt; + pktsz = min_pktsz; + } + } + + size = qemu_send_packet_async(&s->nc, pkt, pktsz, vmnet_send_completed); if (size == 0) { -- 2.30.2