[Qemu-devel] trying to kill a VM

[Alexander Binun]

Hello Friends, 
  I have done a lot of tricks trying to kill a VM - so far in vain :-)

As you told me I have reached the VCPU of the VM to be killed:

struct kvm_vcpu *cpu = (struct kvm_vcpu*)vcpu;
struct pid *vcpu_pid = cpu->pid;
struct task_struct* task = pid_task(vcpu_pid,PIDTYPE_PID);

Then I am trying to kill the VM standing for vcpu_pid in the various ways:

--- kill_pid(task_pid(task), SIGKILL, 1); (SIGTERM is issued as well)
     --- I have tried task_pgrp(task) and task_tgid(task) as well

--- send_sig_info(SIGTERM, &info, task) where struct siginfo info has SIGTERM 
as signo and SI_QUEUE as si_code 

The same result: the host and guest hang! I am forced to reboot the system.

However when I get the VCPU ID manually (by running grep pid 
/var/run/libvirt/qemu/GUEST.xml as it is explained at 
http://chilung.blogspot.co.il/2013/08/kvm-how-to-find-guest-vms-process-id-pid.html)
 and send kill to this ID from the command line, the corresponding VM shuts off!

Which magic does the manual method in order to succeed ?

Thanks in advance, 
     the Israeli team



On Thu 06 Mar 13:28 2014 Paolo Bonzini wrote:
> Il 06/03/2014 11:31, Alexander Binun ha scritto:
> > Then - more questions :
> >    1. How can I access the Qemu process (relevant to a given VM) from 
> > within in the kernel context (being in a kernel module) ?
> 
> The struct pid for the VCPU is in the "pid" field of struct kvm_vcpu.
> 
>  From there if needed you can get the task (with pid_task) and the 
> task's thread group leader (the task's group_leader), and send a signal 
> to it.
> 
> >    2. Should I uninitialize some internal structures for the VM being 
> > killed ?
> 
> No, it will happen automatically.  When QEMU is terminated, the VM's 
> file descriptor is closed and this frees all internal structures.
> 
> >    3. My module detects malicious activities at a VCPU. How can one get the 
> > VM owning this VCPU ?
> 
> Field "kvm" in struct kvm_vcpu points to the struct kvm for the VM.
> 
> Paolo
>