Add trace points to simplify debugging migration.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@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);
+
+ 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);
+}
+
static void tap_send(void *opaque)
{
TAPState *s = opaque;
@@ -199,6 +246,13 @@ static void tap_send(void *opaque)
break;
}
+ if (trace_event_get_state_backends(TRACE_TAP_PACKET_DUMP)) {
+ g_autofree char *dump = tap_dump_packet(s->buf, size);
+ trace_tap_packet_dump(dump);
+ }
+
+ trace_tap_send_packet(s->using_vnet_hdr, s->host_vnet_hdr_len, size);
+
if (s->host_vnet_hdr_len && size <= s->host_vnet_hdr_len) {
/* Invalid packet */
break;
@@ -980,6 +1034,8 @@ int tap_enable(NetClientState *nc)
TAPState *s = DO_UPCAST(TAPState, nc, nc);
int ret;
+ trace_tap_enable();
+
if (s->enabled) {
return 0;
} else {
@@ -997,6 +1053,8 @@ int tap_disable(NetClientState *nc)
TAPState *s = DO_UPCAST(TAPState, nc, nc);
int ret;
+ trace_tap_disable();
+
if (s->enabled == 0) {
return 0;
} else {
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"
--
2.48.1On 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 <vsementsov@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".
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
--
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On 03.09.25 17:11, Daniel P. Berrangé wrote: > 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". Ha, I started to do it, and found that we already have util/hexdump.c :) -- Best regards, Vladimir
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 <vsementsov@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
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