cpu: introduce CPUClass::virtio_is_big_endian()

If we want to support targets that can change endianness (modern PPC and
ARM for the moment), we need to add a per-CPU class method to be called
from the virtio code. The virtio_ prefix in the name is a hint for people
to avoid misusage (aka. anywhere but from the virtio code).

The default behaviour is to return the compile-time default target
endianness.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
virtio: add endian-ambivalent support to VirtIODevice

Some CPU families can dynamically change their endianness. This means we
can have little endian ppc or big endian arm guests for example. This has
an impact on legacy virtio data structures since they are target endian.
We hence introduce a new property to track the endianness of each virtio
device. It is reasonnably assumed that endianness won't change while the
device is in use : we hence capture the device endianness when it gets
reset.

This property should be ideally added to the migration stream, but the
correct way to do it is still under discussion with the QEMU community.
As a workaround, we guess the device endianness at load time out of
the first CPU state.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
virtio: memory accessors for endian-ambivalent targets

This is the virtio-access.h header file taken from Rusty's "endian-ambivalent
targets using legacy virtio" patch. It introduces helpers that should be used
when accessing vring data or by drivers for data that contains headers.
The virtio config space is also target endian, but the current code already
handles that with the virtio_is_big_endian() helper. There is no obvious
benefit at using the virtio accessors in this case.

Now we have two distinct paths: a fast inline one for fixed endian targets,
and a slow out-of-line one for targets that define the new TARGET_IS_BIENDIAN
macro.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
[ relicensed virtio-access.h to GPLv2+ on Rusty's request,
  pass &address_space_memory to physical memory accessors,
  per-device endianness,
  virtio tswap16 and tswap64 helpers,
  Greg Kurz <gkurz@linux.vnet.ibm.com> ]
Cc: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
virtio: allow byte swapping for vring

Quoting original text from Rusty: "This is based on a simpler patch by Anthony
Liguouri".

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
[ add VirtIODevice * argument to most helpers,
  Greg Kurz <gkurz@linux.vnet.ibm.com> ]
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
virtio-net: use virtio wrappers to access headers

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
[ pass VirtIODevice * to memory accessors,
  TCP checksums fix by Cédric Le Goater,
  Greg Kurz <gkurz@linux.vnet.ibm.com> ]
Cc: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
virtio-balloon: use virtio wrappers to access page frame numbers

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
[ pass VirtIODevice * to memory accessors,
  Greg Kurz <gkurz@linux.vnet.ibm.com> ]
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
virtio-blk: use virtio wrappers to access headers

Note that st*_raw and ld*_raw are effectively replaced by st*_p and ld*_p.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
[ pass VirtIODevice * to memory accessors,
  Greg Kurz <gkurz@linux.vnet.ibm.com> ]
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
virtio-scsi: use virtio wrappers to access headers

Note that st*_raw and ld*_raw are effectively replaced by st*_p and ld*_p.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
[ pass VirtIODevice * to memory accessors,
  fix missing tswap32 in virtio_scsi_push_event() by Cédric Le Goater,
  Greg Kurz <gkurz@linux.vnet.ibm.com> ]
Cc: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
virtio-serial-bus: use virtio wrappers to access headers

We also fix max_nr_ports at reset time as the device endianness may have
changed.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
[ pass VirtIODevice * to memory accessors,
  fix max_nr_ports at reset time,
  Greg Kurz <gkurz@linux.vnet.ibm.com> ]
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
virtio-9p: use virtio wrappers to access headers

Note that st*_raw and ld*_raw are effectively replaced by st*_p and ld*_p.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
target-ppc: enable virtio endian ambivalent support

The device endianness is the cpu endianness at device reset time.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>