epapr paravirtualization support is now a Kconfig
selectable option
Signed-off-by: NLiu Yu <yu.liu@freescale.com>
[stuart.yoder@freescale.com: misc minor fixes, description update]
Signed-off-by: NStuart Yoder <stuart.yoder@freescale.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

The "memory" clobber tells the compiler to ensure that all writes to memory
are committed before the hypercall is made.

"memory" is only necessary for hcalls where the Hypervisor will read or
write guest memory. However, we add it to all hcalls because the impact is
minimal, and we want to ensure that it's present for the hcalls that need
it.
Signed-off-by: NTimur Tabi <timur@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

ePAPR hypervisors provide operating system services via a "hypercall"
interface.  The following steps need to be performed to make an hcall:

1. Load r11 with the hcall number
2. Load specific other registers with parameters
3. Issue instrucion "sc 1"
4. The return code is in r3
5. Other returned parameters are in other registers.

To provide this service to the kernel, these steps are wrapped in inline
assembly functions.  Standard ePAPR hcalls are in epapr_hcalls.h, and
Freescale extensions are in fsl_hcalls.h.
Signed-off-by: NTimur Tabi <timur@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>