Arch Linux

dext

Member

From: Poland, Kraków

Registered: 2008-02-01

Posts: 124

Missing KVM

I have a Q5550 based machine. It has VT-x and VT-d, but no EPT. As far as I know, missing EPT is a dealbreaker for VirtualBox and VMware, but KVM requires it only for nested virtualization. Still, I'm getting this:

# dmesg | grep -i kvm
[  512.313684] kvm: no hardware suppor

Yes, I did enable VT-x support in BIOS, like 5 times: disabled it and enabled it again. Anyone has other idea? Google is dry on this topic, just "enable in the bios".

loqs

Member

Registered: 2014-03-06

Posts: 18,911

Re: Missing KVM

Please post the full output of dmesg and lscpu.

dext

Member

From: Poland, Kraków

Registered: 2008-02-01

Posts: 124

Re: Missing KVM

Architecture:           x86_64
  CPU op-mode(s):       32-bit, 64-bit
  Address sizes:        36 bits physical, 48 bits virtual
  Byte Order:           Little Endian
CPU(s):                 4
  On-line CPU(s) list:  0-3
Vendor ID:              GenuineIntel
  BIOS Vendor ID:       Intel            
  Model name:           Intel(R) Core(TM)2 Quad CPU    Q9550  @ 2.83GHz
    BIOS Model name:    Genuine Intel(R)                                    
    CPU family:         6
    Model:              23
    Thread(s) per core: 1
    Core(s) per socket: 4
    Socket(s):          1
    Stepping:           10
    BogoMIPS:           5668.27
    Flags:              fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx
                         fxsr sse sse2 ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good nopl cpui
                        d aperfmperf pni tm2 ssse3 lahf_lm pti dtherm
Caches (sum of all):    
  L1d:                  128 KiB (4 instances)
  L1i:                  128 KiB (4 instances)
  L2:                   12 MiB (2 instances)
NUMA:                   
  NUMA node(s):         1
  NUMA node0 CPU(s):    0-3
Vulnerabilities:        
  Itlb multihit:        KVM: Mitigation: VMX unsupported
  L1tf:                 Mitigation; PTE Inversion
  Mds:                  Vulnerable: Clear CPU buffers attempted, no microcode; SMT disabled
  Meltdown:             Mitigation; PTI
  Spec store bypass:    Vulnerable
  Spectre v1:           Mitigation; usercopy/swapgs barriers and __user pointer sanitization
  Spectre v2:           Mitigation; Full generic retpoline, STIBP disabled, RSB filling
  Srbds:                Not affected
  Tsx async abort:      Not affected

The dmesg: https://paste.ubuntu.com/p/yff6xfTP86/

loqs

Member

Registered: 2014-03-06

Posts: 18,911

Re: Missing KVM

From lspcu output

  Itlb multihit:        KVM: Mitigation: VMX unsupported

While it does not list vmx in Flags.  vmx also refered to as VT-x is required for kernel KVM supported.
https://ark.intel.com/content/www/us/en … z-fsb.html shows the CPU as supporting it.  It could be a special variant of the CPU with it disabled,  broken firmware or vmx is disabled by the kernel although there is no desmg output supporting that possibility.

Lone_Wolf

Administrator

From: Netherlands, Europe

Registered: 2005-10-04

Posts: 15,086

Re: Missing KVM

[    0.000000] Command line: BOOT_IMAGE=/vmlinuz-linux root=UUID=8b27718a-df29-416b-a5d6-3d1917f7d00b rw quiet

For Intel CPUs (VT-d) set intel_iommu=on. Since the kernel config option CONFIG_INTEL_IOMMU_DEFAULT_ON is not set in linux.

Try adding intel_iommu=on .

---

Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.

clean chroot building not flexible enough ?
Try clean chroot manager by graysky

sharow

Member

Registered: 2015-03-10

Posts: 6

Re: Missing KVM

Can you check "Max CPUID Value Limit" option in BIOS?
it is one above VMX-thingy option. make sure set this "[Disabled]".

Last edited by sharow (2021-07-07 00:48:42)