Permit buiding kernels with options VIMAGE, restricted to only a single

active network stack instance.  Turning on options VIMAGE at compile
time yields the following changes relative to default kernel build:

1) V_ accessor macros for virtualized variables resolve to structure
fields via base pointers, instead of being resolved as fields in global
structs or plain global variables.  As an example, V_ifnet becomes:

    options VIMAGE:          ((struct vnet_net *) vnet_net)->_ifnet
    default build:           vnet_net_0._ifnet
    options VIMAGE_GLOBALS:  ifnet

2) INIT_VNET_* macros will declare and set up base pointers to be used
by V_ accessor macros, instead of resolving to whitespace:

    INIT_VNET_NET(ifp->if_vnet); becomes

    struct vnet_net *vnet_net = (ifp->if_vnet)->mod_data[VNET_MOD_NET];

3) Memory for vnet modules registered via vnet_mod_register() is now
allocated at run time in sys/kern/kern_vimage.c, instead of per vnet
module structs being declared as globals.  If required, vnet modules
can now request the framework to provide them with allocated bzeroed
memory by filling in the vmi_size field in their vmi_modinfo structures.

4) structs socket, ifnet, inpcbinfo, tcpcb and syncache_head are
extended to hold a pointer to the parent vnet.  options VIMAGE builds
will fill in those fields as required.

5) curvnet is introduced as a new global variable in options VIMAGE
builds, always pointing to the default and only struct vnet.

6) struct sysctl_oid has been extended with additional two fields to
store major and minor virtualization module identifiers, oid_v_subs and
oid_v_mod.  SYSCTL_V_* family of macros will fill in those fields
accordingly, and store the offset in the appropriate vnet container
struct in oid_arg1.
In sysctl handlers dealing with virtualized sysctls, the
SYSCTL_RESOLVE_V_ARG1() macro will compute the address of the target
variable and make it available in arg1 variable for further processing.

Unused fields in structs vnet_inet, vnet_inet6 and vnet_ipfw have
been deleted.

Reviewed by:	bz, rwatson
Approved by:	julian (mentor)

1 files changed, 3 insertions, 0 deletions

diff --git a/sys/sys/socketvar.h b/sys/sys/socketvar.h
index 8ce97e5abff5..81e6b8825afd 100644
--- a/sys/sys/socketvar.h
+++ b/sys/sys/socketvar.h
@@ -45,6 +45,8 @@
 #include <sys/sockopt.h>
 #endif
 
+struct vnet;
+
 /*
  * Kernel structure per socket.
  * Contains send and receive buffer queues,
@@ -72,6 +74,7 @@ struct socket {
 	short	so_state;		/* (b) internal state flags SS_* */
 	int	so_qstate;		/* (e) internal state flags SQ_* */
 	void	*so_pcb;		/* protocol control block */
+	struct	vnet *so_vnet;		/* network stack instance */
 	struct	protosw *so_proto;	/* (a) protocol handle */
 /*
  * Variables for connection queuing.