nvmm Intel minimum requirements

[Jared McNeill <jmcneill%invisible.ca@localhost>]

What are the min requirements for the Intel nvmm backend? I upgraded my 
Thinkpad T420 to -current today to try it and it says no backends are 
available. CPU is i5-2520M, and HAXM works OK on it.

redux$ cpuctl identify 0
Cannot bind to target CPU.  Output may not accurately describe the target.
Run as root to allow binding.

cpu0: highest basic info 0000000d
cpu0: highest extended info 80000008
cpu0: "Intel(R) Core(TM) i5-2520M CPU @ 2.50GHz"
cpu0: Intel Xeon E3-12xx, 2nd gen i7, i5, i3 2xxx (686-class), 2492.01 MHz
cpu0: family 0x6 model 0x2a stepping 0x7 (id 0x206a7)
cpu0: features 0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE>
cpu0: features 0xbfebfbff<MCA,CMOV,PAT,PSE36,CLFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2>
cpu0: features 0xbfebfbff<SS,HTT,TM,SBF>
cpu0: features1 0x1fbae3ff<SSE3,PCLMULQDQ,DTES64,MONITOR,DS-CPL,VMX,SMX,EST>
cpu0: features1 0x1fbae3ff<TM2,SSSE3,CX16,xTPR,PDCM,PCID,SSE41,SSE42,X2APIC>
cpu0: features1 0x1fbae3ff<POPCNT,DEADLINE,AES,XSAVE,OSXSAVE,AVX>
cpu0: features2 0x28100800<SYSCALL/SYSRET,XD,RDTSCP,EM64T>
cpu0: features3 0x1<LAHF>
cpu0: xsave features 0x7<x87,SSE,AVX>
cpu0: xsave instructions 0x1<XSAVEOPT>
cpu0: xsave area size: current 832, maximum 832, xgetbv enabled
cpu0: enabled xsave 0x7<x87,SSE,AVX>
cpu0: I-cache 32KB 64B/line 8-way, D-cache 32KB 64B/line 8-way
cpu0: L2 cache 256KB 64B/line 8-way
cpu0: L3 cache 3MB 64B/line 12-way
cpu0: 64B prefetching
cpu0: ITLB 64 4KB entries 4-way, 2M/4M: 8 entries
cpu0: DTLB 64 4KB entries 4-way, 2M/4M: 32 entries (L0)
cpu0: L2 STLB 512 4KB entries 4-way
cpu0: Initial APIC ID 2
cpu0: Cluster/Package ID 0
cpu0: Core ID 1
cpu0: SMT ID 0
cpu0: MONITOR/MWAIT extensions 0x3<EMX,IBE>
cpu0: monitor-line size 64
cpu0: C1 substates 2
cpu0: C2 substates 1
cpu0: C3 substates 1
cpu0: C4 substates 2
cpu0: DSPM-eax 0x77<DTS,IDA,ARAT,PLN,ECMD,PTM>
cpu0: DSPM-ecx 0x9<HWF,EPB>
cpu0: SEF highest subleaf 00000000
cpu0: Perfmon-eax 0x7300403<VERSION=0x3,GPCounter=0x4,GPBitwidth=0x30>
cpu0: Perfmon-eax 0x7300403<Vectorlen=0x7>
cpu0: Perfmon-edx 0x603<FixedFunc=0x3,FFBitwidth=0x30>
cpu0: microcode version 0x29, platform ID 4