libvirt users - Mar 2018 - KVM or Qemu

List-

I know this may be slightly off topic and if so tell me to hit up the
emu-discuss mailing list, but does anyone know how to detect the difference
between a guest that is being fully emulates using qemu and a guest that is
running para-virtualized using KVM?


I have and when I inspect the CPUs I see the following....

# cat /proc/cpuinfo

processor : 0

vendor_id : GenuineIntel

cpu family : 6

model : 13

model name : QEMU Virtual CPU version 1.5.3

stepping : 3

microcode : 0x1

cpu MHz : 1995.312

cache size : 4096 KB

physical id : 0

siblings : 1

core id : 0

cpu cores : 1

apicid : 0

initial apicid : 0

fpu : yes

fpu_exception : yes

cpuid level : 4

wp : yes

flags : fpu de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pse36
clflush mmx fxsr sse sse2 syscall nx lm rep_good nopl pni cx16 hypervisor
lahf_lm abm

bogomips : 3990.62

clflush size : 64

cache_alignment : 64

address sizes : 46 bits physical, 48 bits virtual

power management:


# dmidecode

# dmidecode 2.12-dmifs

SMBIOS 2.4 present.

10 structures occupying 326 bytes.

Table at 0x000F7190.


Handle 0x0000, DMI type 0, 24 bytes

BIOS Information

Vendor: Seabios

Version: 0.5.1

Release Date: 01/01/2011

Address: 0xE8000

Runtime Size: 96 kB

ROM Size: 64 kB

Characteristics:

BIOS characteristics not supported

Targeted content distribution is supported

BIOS Revision: 1.0


Handle 0x0100, DMI type 1, 27 bytes

System Information

Manufacturer: Red Hat

Product Name: KVM

Version: RHEL 7.0.0 PC (i440FX + PIIX, 1996)

Serial Number: Not Specified

UUID: 1851A1FE-5ABB-42BD-B651-1A5931ADEE40

Wake-up Type: Power Switch

SKU Number: Not Specified

Family: Red Hat Enterprise Linux


Handle 0x0300, DMI type 3, 20 bytes

Chassis Information

Manufacturer: Bochs

Type: Other

Lock: Not Present

Version: Not Specified

Serial Number: Not Specified

Asset Tag: Not Specified

Boot-up State: Safe

Power Supply State: Safe

Thermal State: Safe

Security Status: Unknown

OEM Information: 0x00000000

Height: Unspecified

Number Of Power Cords: Unspecified


Handle 0x0401, DMI type 4, 32 bytes

Processor Information

Socket Designation: CPU 1

Type: Central Processor

Family: Other

Manufacturer: Bochs

ID: D3 06 00 00 FD FB 8B 07

Version: Not Specified

Voltage: Unknown

External Clock: Unknown

Max Speed: 2000 MHz

Current Speed: 2000 MHz

Status: Populated, Enabled

Upgrade: Other

L1 Cache Handle: Not Provided

L2 Cache Handle: Not Provided
L3 Cache Handle: Not Provided


 Since it is report a Qemu cpu and Manufacturer Bochs I am suspecting that
it is qemu fully emulated vs KVM para-virtualized.

On Mon, Mar 12, 2018 at 03:24:58PM -0400, Jamie Fargen
wrote:
> List-
> 
> I know this may be slightly off topic and if so tell me to hit up the
> emu-discuss mailing list, but does anyone know how to detect the difference
> between a guest that is being fully emulates using qemu and a guest that is
> running para-virtualized using KVM?
[snip]
>  Since it is report a Qemu cpu and Manufacturer Bochs I am suspecting that
> it is qemu fully emulated vs KVM para-virtualized.
Unfortunately that's not sufficient to distinguish it. The fairly
"standard"
way to identify different hypervisors at a technical level on x86 is to read
CPUID leaf 0x40000000.  For KVM it reports the string
"KVMKVMKVM\0\0\0"
while on QEMU >= 2.10 it reports "TCGTCGTCGTCG" for QEMU emulation.

In general it is best not to try this yourself and instead just run the
"virt-what" command, as there are many other heuristics to check for
various hypervisors / architectures.

Regards,
Daniel
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