[PATCH v2 1/7] tap: Move the tap_hdr file to a separate file

[PATCH v2 1/7] tap: Move the tap_hdr file to a separate file

[Ammar Yasser]

It was defined in tap.h, put it on its own so that future callers won't
need to depend on all definitions in tap.h.
Also turn it into a union of a vnet_len and virtio_net_mrg_rxbuf
because for vhost acceleration the frames will have this virtio net
header prepended to them.

Signed-off-by: Ammar Yasser <aerosound161@gmail.com>
---
 tap.h     |  9 +--------
 tap_hdr.h | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+), 8 deletions(-)
 create mode 100644 tap_hdr.h

diff --git a/tap.h b/tap.h
index b335933..1625975 100644
--- a/tap.h
+++ b/tap.h
@@ -10,6 +10,7 @@
 #include <stdint.h>

 #include "passt.h"
+#include "tap_hdr.h"

 /** L2_MAX_LEN_PASTA - Maximum frame length for pasta mode (with L2 header)
  *
@@ -38,14 +39,6 @@

 struct udphdr;

-/**
- * struct tap_hdr - tap backend specific headers
- * @vnet_len:	Frame length (for qemu socket transport)
- */
-struct tap_hdr {
-	uint32_t vnet_len;
-} __attribute__((packed));
-
 /**
  * tap_hdr_iov() - struct iovec for a tap header
  * @c:		Execution context
diff --git a/tap_hdr.h b/tap_hdr.h
new file mode 100644
index 0000000..4156f44
--- /dev/null
+++ b/tap_hdr.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright (c) 2021 Red Hat GmbH
+ * Author: David Gibson <david@gibson.dropbear.id.au>
+ */
+
+#ifndef TAP_HDR_H
+#define TAP_HDR_H
+
+#include <stdint.h>
+#include <linux/virtio_net.h>
+
+/**
+ * struct tap_hdr - tap backend specific headers
+ * @vnet_len:	Frame length (for qemu socket transport)
+ */
+struct tap_hdr {
+	union {
+		uint32_t vnet_len;
+		struct virtio_net_hdr_mrg_rxbuf hdr;
+	};
+};
+
+#endif /* TAP_HDR_H */
--
2.39.5 (Apple Git-154)

[PATCH v2 0/7] Add vhost-net kernel support to pasta

[aerosouund]

From: Ammar Yasser <aerosound161@gmail.com>

This work is based on the original v2 RFC by Eugenio Perez:

Link:
https://archives.passt.top/passt-dev/20250709174748.3514693-1-eperezma@redhat.com/

It is the first finished patch series for vhost-kernel support after a
third RFC was submitted:

Link:
https://archives.passt.top/passt-dev/20260802132155.870796-1-aerosound161@gmail.com/

vhost-net is a kernel device that allows reading and writing packets to a
tap device using virtqueues instead of read(2), write(2), and their
vectored counterparts. Frames are handed over through a shared descriptor
ring, so several of them can be passed to the kernel at once rather than
issuing a syscall per frame.

The changes reliably yield a roughly 2x speedup on the TX path (container
to host).

Numbers were obtained through iperf3 with the following methodology and
results:

Pasta command:
./pasta -f --runas 0:0 --map-guest-addr 192.168.0.5
--vhost-kernel on --config-net 2729785

Host:
iperf3 -s1J

Container:
iperf3 -c 192.168.0.5 -t 10 -P4 -l 1M -w 32M -i1

With --vhost-kernel on:

[SUM]   0.00-10.00  sec  1.36 GBytes  1.17 Gbits/sec  3643 sender
[SUM]   0.00-10.00  sec  1.16 GBytes   999 Mbits/sec        receiver

With --vhost-kernel off:

[SUM]   0.00-10.00  sec   700 MBytes   587 Mbits/sec  3556 sender
[SUM]   0.00-10.10  sec   495 MBytes   411 Mbits/sec        receiver

v2:
- removed all use of epoll_ctl in vhost_setup_eventfds in favor of epoll_add
- prevent all functions that register memory regions into the vhost_memory
  object from overflowing
- remove the unions with flexible array members in vring_avail_pasta and
  vring_used_pasta in favor of hardcoding the ring array to have VHOST_NDESCS
  entries to avoid having to ignore Wpedantic
- remove the && operator with TCP_CURR_IDX when computing no_csum
- make desc_id in tx_reap a uint32_t
- don't make vhost-kernel a required argument

Ammar Yasser (7):
  tap: Move the tap_hdr file to a separate file
  conf: Add context fields, epoll types and --vhost-kernel flag to pasta
  virtio: Add the pasta vhost-net interface and implementation
  tap: Implement the pasta vhost-net from-guest path
  tap, tcp, udp: Prepare the to-guest path for vhost-net
  tap: Implement the pasta vhost-net to-guest path
  tap/tcp: Replace tcp_payload_used with a ring buffer style index

 Makefile     |   2 +-
 conf.c       |  19 +++
 epoll_type.h |   4 +
 passt.c      |   9 ++
 passt.h      |  79 ++++++++++-
 tap.c        | 368 +++++++++++++++++++++++++++++++++++++++++++++------
 tap.h        |  47 ++-----
 tap_hdr.h    |  23 ++++
 tcp_buf.c    | 149 ++++++++++++++++-----
 tcp_buf.h    |   4 +
 udp.c        |  47 +++++--
 udp.h        |   3 +
 util.c       |  18 +++
 util.h       |   2 +
 vhost.c      | 295 +++++++++++++++++++++++++++++++++++++++++
 vhost.h      |  91 +++++++++++++
 16 files changed, 1036 insertions(+), 124 deletions(-)
 create mode 100644 tap_hdr.h
 create mode 100644 vhost.c
 create mode 100644 vhost.h

--
2.39.5 (Apple Git-154)

[PATCH v2 1/7] tap: Move the tap_hdr file to a separate file

[aerosouund]

From: Ammar Yasser <aerosound161@gmail.com>

It was defined in tap.h, put it on its own so that future callers won't
need to depend on all definitions in tap.h.
Also turn it into a union of a vnet_len and virtio_net_mrg_rxbuf
because for vhost acceleration the frames will have this virtio net
header prepended to them.

Signed-off-by: Ammar Yasser <aerosound161@gmail.com>
---
 tap.h     |  9 +--------
 tap_hdr.h | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+), 8 deletions(-)
 create mode 100644 tap_hdr.h

diff --git a/tap.h b/tap.h
index b335933..1625975 100644
--- a/tap.h
+++ b/tap.h
@@ -10,6 +10,7 @@
 #include <stdint.h>

 #include "passt.h"
+#include "tap_hdr.h"

 /** L2_MAX_LEN_PASTA - Maximum frame length for pasta mode (with L2 header)
  *
@@ -38,14 +39,6 @@

 struct udphdr;

-/**
- * struct tap_hdr - tap backend specific headers
- * @vnet_len:	Frame length (for qemu socket transport)
- */
-struct tap_hdr {
-	uint32_t vnet_len;
-} __attribute__((packed));
-
 /**
  * tap_hdr_iov() - struct iovec for a tap header
  * @c:		Execution context
diff --git a/tap_hdr.h b/tap_hdr.h
new file mode 100644
index 0000000..4156f44
--- /dev/null
+++ b/tap_hdr.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright (c) 2021 Red Hat GmbH
+ * Author: David Gibson <david@gibson.dropbear.id.au>
+ */
+
+#ifndef TAP_HDR_H
+#define TAP_HDR_H
+
+#include <stdint.h>
+#include <linux/virtio_net.h>
+
+/**
+ * struct tap_hdr - tap backend specific headers
+ * @vnet_len:	Frame length (for qemu socket transport)
+ */
+struct tap_hdr {
+	union {
+		uint32_t vnet_len;
+		struct virtio_net_hdr_mrg_rxbuf hdr;
+	};
+};
+
+#endif /* TAP_HDR_H */
--
2.39.5 (Apple Git-154)