diff mbox series

[PULL,28/29] net/vmnet: Pad short Ethernet frames

Message ID 20241231202228.28819-29-philmd@linaro.org
State Accepted
Commit 79b6a98587c65c8b8fdde8eb778396f1fc98a852
Headers show
Series [PULL,01/29] hw/pci-host/gpex: Allow more than 4 legacy IRQs | expand

Commit Message

Philippe Mathieu-Daudé Dec. 31, 2024, 8:22 p.m. UTC 
From: William Hooper <wsh@wshooper.org>

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 <wsh@wshooper.org>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2058
Reviewed-by: Phil Dennis-Jordan <phil@philjordan.eu>
Message-ID: <20241102205653.30476-1-wsh@wshooper.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 net/vmnet-common.m | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/net/vmnet-common.m b/net/vmnet-common.m
index dba5b5bab13..54d900ba679 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 <vmnet/vmnet.h>
 #include <dispatch/dispatch.h>
@@ -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) {