On Sat, Oct 06, 2018 at 12:19:45PM +0300, Raz wrote:

Hey
How does HVSC works ?
I looked in the code and LoPAR documentation. It looks like there is
vector called
system_call_pSeries ( at 0xc00 ) that is supposed to be called when we
invoke HVSC from kernel
mode.
Now, I wrote a NULL call HSVC and patched the exceptions-64s.S to
return RFID immediately.
This does not work.
Would you be so kind to explain how HVSC works ?
thank you

If your kernel is not running in hypervisor mode, sc 1 does not call the
kernel (but the hypervisor, instead).  If your kernel _is_ running in
hypervisor mode, sc 1 does the same as sc 0, a normal system call.

I don't know which it is for you; you didn't say.

I have no idea what "a NULL call HSVC" means.  If you make exception c00
return immediately (as you suggest) then you have made all system calls
non-functional, which indeed is unlikely to work as you want.


Segher