Recommended way access KVM data structures from other kernel subsystems ?

Recommended way access KVM data structures from other kernel subsystems ?

[Pandarathil, Vijaymohan R]

Hi,

I am looking for the recommended approach for accessing KVM driver data from other kernel components. In my case, I need to set some global variable/state in KVM driver from one of the NMI handlers.  I see that using kvm_x86_ops is one option. I can define a new function as part of kvm_x86_ops and invoke that function from the NMI handler as below.

nmi_handler() {

...
       If (kvm_x86_ops) {
		kvm_x86_ops->new_fn();

}

after adding new_func() to struct kvm_x86_ops.

Is this the right approach ? Or is there some other existing mechanism ? Is KVM driver always loaded ?
I am fairly new to KVM and so any guidance is very much appreciated.

Thanks

Vijay

Re: Recommended way access KVM data structures from other kernel subsystems ?

[Avi Kivity]

On 08/23/2012 10:49 AM, Pandarathil, Vijaymohan R wrote:
> Hi,
> 
> I am looking for the recommended approach for accessing KVM driver data from other kernel components. In my case, I need to set some global variable/state in KVM driver from one of the NMI handlers.  I see that using kvm_x86_ops is one option. I can define a new function as part of kvm_x86_ops and invoke that function from the NMI handler as below.
> 
> nmi_handler() {
> 
> ...
>        If (kvm_x86_ops) {
> 		kvm_x86_ops->new_fn();
> 
> }
> 
> after adding new_func() to struct kvm_x86_ops.
> 
> Is this the right approach ? 

No, kvm_x86_ops is not available to the core kernel code.

> Or is there some other existing mechanism ? Is KVM driver always loaded ?

No.

> I am fairly new to KVM and so any guidance is very much appreciated.

Do something like

  void nmi_xyz_register(struct nmi_xyz *x);
  void nmi_xyz_unregister(struct nmi_xyz *x);

  struct nmi_xyz {
      void (*nmi)(void);
  };

then add code to kvm to use nmi_xyz (whatever that is).

-- 
error compiling committee.c: too many arguments to function