kvm tools: Introduce ethernet frame buffer system for uip

- uip_buf_get_free()
  Get a free buffer from buffer pool, sleep if there is no free buffer.

- uip_buf_get_used()
  Get a used buffer from buffer pool, sleep if there is no used buffer.

- uip_buf_set_free()
  Set a buffer as free, so it can be reused by the buffer producer.

- uip_buf_set_used()
  Set a buffer as used, uip rx code will inject the ethernet frame in
  this buffer into guest.

- uip_buf_clone()
  Get a free buffer, and clone data into it.

Signed-off-by: Asias He <asias.hejun@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

Makefile

@@ -45,6 +45,7 @@ OBJS	+= disk/qcow.o
 OBJS	+= disk/raw.o
 OBJS	+= ioeventfd.o
 OBJS	+= irq.o
+OBJS	+= uip/buf.o
 OBJS	+= kvm-cmd.o
 OBJS	+= kvm-debug.o
 OBJS	+= kvm-help.o

include/kvm/uip.h

@@ -0,0 +1,69 @@
+#ifndef KVM__UIP_H
+#define KVM__UIP_H
+
+#include "linux/types.h"
+#include "kvm/mutex.h"
+
+#include <netinet/in.h>
+#include <sys/uio.h>
+
+#define UIP_BUF_STATUS_FREE	0
+#define UIP_BUF_STATUS_INUSE	1
+#define UIP_BUF_STATUS_USED	2
+
+struct uip_eth_addr {
+	u8 addr[6];
+};
+
+struct uip_eth {
+	struct uip_eth_addr dst;
+	struct uip_eth_addr src;
+	u16 type;
+} __attribute__((packed));
+
+struct uip_info {
+	struct list_head udp_socket_head;
+	struct list_head tcp_socket_head;
+	pthread_mutex_t udp_socket_lock;
+	pthread_mutex_t tcp_socket_lock;
+	struct uip_eth_addr guest_mac;
+	struct uip_eth_addr host_mac;
+	pthread_cond_t buf_free_cond;
+	pthread_cond_t buf_used_cond;
+	struct list_head buf_head;
+	pthread_mutex_t buf_lock;
+	pthread_t udp_thread;
+	int udp_epollfd;
+	int buf_free_nr;
+	int buf_used_nr;
+	u32 host_ip;
+	u32 buf_nr;
+};
+
+struct uip_buf {
+	struct list_head list;
+	struct uip_info *info;
+	u32 payload;
+	int vnet_len;
+	int eth_len;
+	int status;
+	char *vnet;
+	char *eth;
+	int id;
+};
+
+struct uip_tx_arg {
+	struct virtio_net_hdr *vnet;
+	struct uip_info *info;
+	struct uip_eth *eth;
+	int vnet_len;
+	int eth_len;
+};
+
+struct uip_buf *uip_buf_set_used(struct uip_info *info, struct uip_buf *buf);
+struct uip_buf *uip_buf_set_free(struct uip_info *info, struct uip_buf *buf);
+struct uip_buf *uip_buf_get_used(struct uip_info *info);
+struct uip_buf *uip_buf_get_free(struct uip_info *info);
+struct uip_buf *uip_buf_clone(struct uip_tx_arg *arg);
+
+#endif /* KVM__UIP_H */

uip/buf.c

@@ -0,0 +1,114 @@
+#include "kvm/uip.h"
+
+#include <linux/kernel.h>
+#include <linux/list.h>
+
+struct uip_buf *uip_buf_get_used(struct uip_info *info)
+{
+	struct uip_buf *buf;
+	bool found = false;
+
+	mutex_lock(&info->buf_lock);
+
+	while (!(info->buf_used_nr > 0))
+		pthread_cond_wait(&info->buf_used_cond, &info->buf_lock);
+
+	list_for_each_entry(buf, &info->buf_head, list) {
+		if (buf->status == UIP_BUF_STATUS_USED) {
+			/*
+			 * Set status to INUSE immediately to prevent
+			 * someone from using this buf until we free it
+			 */
+			buf->status = UIP_BUF_STATUS_INUSE;
+			info->buf_used_nr--;
+			found = true;
+			break;
+		}
+	}
+
+	mutex_unlock(&info->buf_lock);
+
+	return found ? buf : NULL;
+}
+
+struct uip_buf *uip_buf_get_free(struct uip_info *info)
+{
+	struct uip_buf *buf;
+	bool found = false;
+
+	mutex_lock(&info->buf_lock);
+
+	while (!(info->buf_free_nr > 0))
+		pthread_cond_wait(&info->buf_free_cond, &info->buf_lock);
+
+	list_for_each_entry(buf, &info->buf_head, list) {
+		if (buf->status == UIP_BUF_STATUS_FREE) {
+			/*
+			 * Set status to INUSE immediately to prevent
+			 * someone from using this buf until we free it
+			 */
+			buf->status = UIP_BUF_STATUS_INUSE;
+			info->buf_free_nr--;
+			found = true;
+			break;
+		}
+	}
+
+	mutex_unlock(&info->buf_lock);
+
+	return found ? buf : NULL;
+}
+
+struct uip_buf *uip_buf_set_used(struct uip_info *info, struct uip_buf *buf)
+{
+	mutex_lock(&info->buf_lock);
+
+	buf->status = UIP_BUF_STATUS_USED;
+	info->buf_used_nr++;
+	pthread_cond_signal(&info->buf_used_cond);
+
+	mutex_unlock(&info->buf_lock);
+
+	return buf;
+}
+
+struct uip_buf *uip_buf_set_free(struct uip_info *info, struct uip_buf *buf)
+{
+	mutex_lock(&info->buf_lock);
+
+	buf->status = UIP_BUF_STATUS_FREE;
+	info->buf_free_nr++;
+	pthread_cond_signal(&info->buf_free_cond);
+
+	mutex_unlock(&info->buf_lock);
+
+	return buf;
+}
+
+struct uip_buf *uip_buf_clone(struct uip_tx_arg *arg)
+{
+	struct uip_buf *buf;
+	struct uip_eth *eth2;
+	struct uip_info *info;
+
+	info = arg->info;
+
+	/*
+	 * Get buffer from device to guest
+	 */
+	buf = uip_buf_get_free(info);
+
+	/*
+	 * Clone buffer
+	 */
+	memcpy(buf->vnet, arg->vnet, arg->vnet_len);
+	memcpy(buf->eth, arg->eth, arg->eth_len);
+	buf->vnet_len	= arg->vnet_len;
+	buf->eth_len	= arg->eth_len;
+
+	eth2		= (struct uip_eth *)buf->eth;
+	eth2->src	= info->host_mac;
+	eth2->dst	= arg->eth->src;
+
+	return buf;
+}