[Bug 1850751] [NEW] kvm flag is not exposed by default

[Leoyzen Liu]

Public bug reported:

Hi I found that the kvm flags is not exposed by default, but according
to the source code, it should be exposed by default when the CPU Model
is a X86CPU.

we have to specifically add "kvm=on" in QEMU custom cpu args like this to make 
VMWare Timing and KVM-Clock work:
<qemu:arg value='host,kvm=on,+invtsc,+hypervisor'/>

Also the libvirt can't expose kvm because of this (libvirt assumes the
kvm flag is exposed by default in QEMU, so only "kvm hidden = 'true'"
can be used to disable the kvm expose flag.

I'm using QEMU 4.1.0 and libvirt 20190803.

** Affects: qemu
     Importance: Undecided
         Status: New

** Description changed:

  Hi I found that the kvm flags is not exposed by default, but according
  to the source code, it should be exposed by default when the CPU Model
  is a X86CPU.
  
- we have to specifically add "kvm=on" in QEMU custom cpu args like this:
+ we have to specifically add "kvm=on" in QEMU custom cpu args like this to 
make VMWare Timing and KVM-Clock work:
  <qemu:arg value='host,kvm=on,+invtsc,+hypervisor'/>
  
  Also the libvirt can't expose kvm because this (libvirt assumes the kvm
  flag is exposed by default, only "kvm hidden = 'true'" can be used.
+ 
+ I'm using QEMU 4.1.0 and libvirt 20190803.

** Description changed:

  Hi I found that the kvm flags is not exposed by default, but according
  to the source code, it should be exposed by default when the CPU Model
  is a X86CPU.
  
  we have to specifically add "kvm=on" in QEMU custom cpu args like this to 
make VMWare Timing and KVM-Clock work:
  <qemu:arg value='host,kvm=on,+invtsc,+hypervisor'/>
  
- Also the libvirt can't expose kvm because this (libvirt assumes the kvm
- flag is exposed by default, only "kvm hidden = 'true'" can be used.
+ Also the libvirt can't expose kvm because of this (libvirt assumes the
+ kvm flag is exposed by default in QEMU, so only "kvm hidden = 'true'"
+ can be used to disable the kvm expose flag.
  
  I'm using QEMU 4.1.0 and libvirt 20190803.

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https://bugs.launchpad.net/bugs/1850751

Title:
  kvm flag is not exposed by default

Status in QEMU:
  New

Bug description:
  Hi I found that the kvm flags is not exposed by default, but according
  to the source code, it should be exposed by default when the CPU Model
  is a X86CPU.

  we have to specifically add "kvm=on" in QEMU custom cpu args like this to 
make VMWare Timing and KVM-Clock work:
  <qemu:arg value='host,kvm=on,+invtsc,+hypervisor'/>

  Also the libvirt can't expose kvm because of this (libvirt assumes the
  kvm flag is exposed by default in QEMU, so only "kvm hidden = 'true'"
  can be used to disable the kvm expose flag.

  I'm using QEMU 4.1.0 and libvirt 20190803.

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