Kexec and KVM not working gracefully together

[Frediano Ziglio]

Hi,
  I was trying to make kexec (software reset) work on an ARM platform
and I realized that the kernel launched with kexec cannot use KVM.
Looking for message I get from kernel and code the situation is this:
1- kernel start in HYP mode but then kvm code switch to SVC mode and
initialize HYP mode with its code;
2- kexec call reboot with LINUX_REBOOT_CMD_KEXEC
3- kernel call kernel_exec;
4- kernel_exec calls machine_kexec;
5- machine_kexec calls soft_restart passing physical entry point for
next in memory kernel;
6- soft_restart calls __soft_restart changing stack;
7- __soft_restart calls cpu_reset (which in my case is defined as cpu_v7_reset);
8- cpu_v7_reset just disable MMU (it's in an identity memory) and
calls next kernel entry point.

>From point 3 to 8 kernel is always in SVC mode so next kernel is
launched in SVC mode too but initial kernel was launched in HYP mode.

I used kernel 3.14 but looking at 3.19 rc code there is the same issue
(code didn't change).

Using hvc instruction you can execute arbitrary functions however
these function must be in a very restricted range as HYP code MMU has
very limited paged configured and cpu_v7_reset is not one of these
functions.

My idea to fix the issue is before calling cpu_reset call a new
kvm_exit or similar that turn into HYP mode with MMU set as SVC mode.

Is this a known issue? Should I try to fix the problem or somebody can
easily fix it?

Regards,
  Frediano