On 03.09.25 17:11, Daniel P. Berrangé wrote:
On Wed, Sep 03, 2025 at 04:36:58PM +0300, Vladimir Sementsov-Ogievskiy wrote:
Add trace points to simplify debugging migration.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@yandex-team.ru>
---
net/tap.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++
net/trace-events | 7 ++++++
2 files changed, 65 insertions(+)
diff --git a/net/tap.c b/net/tap.c
index 2530627a9a..224fb37310 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -43,6 +43,7 @@
#include "qemu/main-loop.h"
#include "qemu/sockets.h"
#include "hw/virtio/vhost.h"
+#include "trace.h"
#include "net/tap.h"
@@ -148,6 +149,9 @@ static ssize_t tap_receive_iov(NetClientState *nc, const struct iovec *iov,
g_autofree struct iovec *iov_copy = NULL;
struct virtio_net_hdr hdr = { };
+ trace_tap_receive_iov(s->using_vnet_hdr, s->host_vnet_hdr_len, iovcnt,
+ iov->iov_len);
+
if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
iov_copy = g_new(struct iovec, iovcnt + 1);
iov_copy[0].iov_base = &hdr;
@@ -183,6 +187,49 @@ static void tap_send_completed(NetClientState *nc, ssize_t
len)
tap_read_poll(s, true);
}
+static char *tap_dump_packet(const uint8_t *buf, int size)
+{
+ int i, j;
+ char hex_line[80]; /* Enough space for hex pairs + spaces */
+ char ascii_line[17]; /* 16 + 1 for null terminator */
+ GString *dump_str = g_string_new(NULL);
+
+ g_string_append_printf(dump_str, "Packet dump (%d bytes):\n", size);
It occurrs to me that this ability to dump a buffer is likely useful for
other areas of QEMU. How about moving this to somewhere in util/ and
renaming it to something like "dump_buffer".
Agreed, will do.
You can drop the 'Packet dump' prefix, and bytes count, as you can
include that info in the trace-events format string instead.
+
+ for (i = 0; i < size; i += 16) {
+ memset(hex_line, 0, sizeof(hex_line));
+ memset(ascii_line, 0, sizeof(ascii_line));
+
+ /* Build hex line in groups of 2 bytes (4 hex chars) */
+ int hex_pos = 0;
+ for (j = 0; j < 16 && (i + j) < size; j += 2) {
+ if (i + j + 1 < size) {
+ /* Two bytes available */
+ hex_pos += snprintf(hex_line + hex_pos,
+ sizeof(hex_line) - hex_pos,
+ "%02x%02x ", buf[i + j], buf[i + j + 1]);
+ } else {
+ /* Only one byte left */
+ hex_pos += snprintf(hex_line + hex_pos,
+ sizeof(hex_line) - hex_pos,
+ "%02x ", buf[i + j]);
+ }
+ }
+
+ /* Build ASCII line */
+ for (j = 0; j < 16 && (i + j) < size; j++) {
+ uint8_t byte = buf[i + j];
+ ascii_line[j] = (byte >= 32 && byte <= 126) ? byte : '.';
+ }
+
+ /* Add the line in tcpdump-like format */
+ g_string_append_printf(dump_str, "\t0x%04x: %-40s %s\n",
+ i, hex_line, ascii_line);
+ }
+
+ return g_string_free(dump_str, false);
+}
diff --git a/net/trace-events b/net/trace-events
index cda960f42b..b51427f539 100644
--- a/net/trace-events
+++ b/net/trace-events
@@ -29,3 +29,10 @@ vhost_vdpa_set_address_space_id(void *v, unsigned vq_group,
unsigned asid_num) "
vhost_vdpa_net_load_cmd(void *s, uint8_t class, uint8_t cmd, int data_num, int
data_size) "vdpa state: %p class: %u cmd: %u sg_num: %d size: %d"
vhost_vdpa_net_load_cmd_retval(void *s, uint8_t class, uint8_t cmd, int r) "vdpa
state: %p class: %u cmd: %u retval: %d"
vhost_vdpa_net_load_mq(void *s, int ncurqps) "vdpa state: %p current_qpairs:
%d"
+
+# tap.c
+tap_receive_iov(bool using_vnet_hdr, uint32_t host_vnet_hdr_len, int iovcnt, size_t
iov_len) "using_vnet_hdr:%d host_vnet_hdr_len:%u iovcnt:%d iov_len:%zu"
+tap_send_packet(bool using_vnet_hdr, uint32_t host_vnet_hdr_len, int size)
"using_vnet_hdr:%d host_vnet_hdr_len:%u size:%d"
+tap_enable(void) "tap enabled"
+tap_disable(void) "tap disabled"
+tap_packet_dump(const char *dump_str) "%s"
This could be
tap_packet_dump(size_t bytes, const char *dump_str) "Package dump (%zu bytes)
%s"
With regards,
Daniel
--
Best regards,
Vladimir
