ports/143648: AMD-V is not recognized on amd64 with virtualbox 3.1.2_1

[pieterb at gewis.nl]

>Number:         143648
>Category:       ports
>Synopsis:       AMD-V is not recognized on amd64 with virtualbox 3.1.2_1
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-ports-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Feb 07 15:20:01 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator:     PieterB
>Release:        FreeBSD 8.0-RELEASE amd64
>Organization:
>Environment:
System: FreeBSD ve.lan 8.0-RELEASE FreeBSD 8.0-RELEASE #0: Sat Nov 21 15:02:08 UTC 2009 root at mason.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC amd64

Relevant CPU details from /var/log/messages:

CPU: AMD Phenom(tm) II X3 720 Processor (2812.83-MHz K8-class CPU)
Origin = "AuthenticAMD"  Id = 0x100f42  Stepping = 2
Features=0x178bfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2,HTT>
Features2=0x802009<SSE3,MON,CX16,POPCNT>
AMD Features=0xee500800<SYSCALL,NX,MMX+,FFXSR,Page1GB,RDTSCP,LM,3DNow!+,3DNow!>
AMD Features2=0x37ff<LAHF,CMP,SVM,ExtAPIC,CR8,ABM,SSE4A,MAS,Prefetch,OSVW,IBS,SKINIT,WDT>

>Description:
I upgraded my virtual box from 3.0.51 to 3.1.2
following the instructions from 
http://wiki.freebsd.org/VirtualBox

After that starting a virtual machine gives an error:

Failed to start the virtual machine foobar.
VT-x is not available. (VERR_VMX_NO_VMX).
Unknown error creating VM (VERR_VMX_NO_VMX).

Result Code: NS_ERROR_FAILURE (0x80004005)
Component: Console
Interface: IConsole {6375231a-c17c-464b-92cb-ae9e128d71c3}

The same virtual machine worked fine with virtualbox 3.0.51.
The VT-x/AMD-V is enabled for the virtual machine (disabling does not work either).

>How-To-Repeat:
	Upgrade virtualbox 3.0.51 and try to start a virtual machine.
>Fix:

I don't know of a fix. I migrated to Proxmox ve because of this issue.


>Release-Note:
>Audit-Trail:
>Unformatted: