[Qemu-devel] [PATCH 00/15] [RFC] MMIO endianness cleanup

[Alexander Graf <agraf@suse.de>]

The way mmio endianness is currently implemented is horrifying.

In the real world, CPUs have an endianness and write out data
to the memory bus. Instead of RAM, a receiving side here can be
a device. This device gets a byte stream again and needs to
make sense of it.

Since big endian systems write big endian numbers into memory
while little endian systems write little endian numbers there,
the device and software on the CPU need to be aware of this.

In practice, most devices these days (ISA, PCI) assume that
the data is little endian. So to communicate with such a device
from the CPU's side, the OS byte swaps all MMIO.

In qemu however, we simply pass the register value we find on
to the device. So any byte mangling the guest does to compensate
for the transfer screw us up by exposing byte swapped MMIO
on the device's side.

The way this has been fixed historically is by constructs like
this one:

#ifdef TARGET_WORDS_BIGENDIAN
    val = bswap32(val);
#endif

With the move to get device code only compiled once, this has
become harder and harder to justify though, since we don't know
the target endianness during compile time.

It's especially bad since it doesn't make any sense at all to
clutter all the device code with endianness workarounds, aside
from the fact that about 80% of the device code currently does
the wrong thing :).

So my solution to the issue is to make every device define if
it's a little, big or native (target) endianness device. This
basically tells the layers below what endianness the device
expects mmio to occur in. Little endian devices on little endian
hosts don't swap. On big endian hosts they do. Same the other
way around.

The only reason I added "native" endianness is that we have some
PV devices like the fw_cfg that expect qemu's broken behavior.
These devices are the minority though. In the long run I'd expect
to see most code be committed with either of the two endianness
choices.

The patch set also includes a bunch of conversions for devices
that were already aware of endianness.

This is an RFC, so please comment as much as you can :).

Alexander Graf (15):
  exec: introduce endianness swapped mmio
  Add endianness as io mem parameter
  Make simple io mem handler endian aware
  dbdma: Make little endian
  pci-host: Delegate bswap to mmio layer
  uninorth: Get rid of bswap
  e1000: Make little endian
  prep: Declare as little endian
  versatile_pci: Declare as little endian
  ppc4xx_pci: Declare as little endian
  openpic: Replace explicit byte swap with endian hints
  rtl8139: Declare as little endian
  heathrow_pic: Declare as little endian
  isa_mmio: Always use little endian
  usb_ohci: Always use little endian

 Makefile.objs              |    3 +
 Makefile.target            |    7 --
 cpu-common.h               |    6 ++-
 exec.c                     |  145 +++++++++++++++++++++++++++++++++++++++++---
 hw/apb_pci.c               |    9 ++-
 hw/apic.c                  |    3 +-
 hw/arm_gic.c               |    3 +-
 hw/arm_sysctl.c            |    3 +-
 hw/arm_timer.c             |    5 +-
 hw/armv7m.c                |    2 +-
 hw/axis_dev88.c            |    6 +-
 hw/bonito.c                |   19 ++++--
 hw/cirrus_vga.c            |   12 +++-
 hw/cs4231.c                |    3 +-
 hw/cuda.c                  |    3 +-
 hw/dec_pci.c               |    6 +-
 hw/dp8393x.c               |    3 +-
 hw/ds1225y.c               |    6 +-
 hw/e1000.c                 |   11 +---
 hw/eccmemctl.c             |    6 +-
 hw/eepro100.c              |    3 +-
 hw/empty_slot.c            |    3 +-
 hw/escc.c                  |    3 +-
 hw/esp.c                   |    3 +-
 hw/etraxfs_dma.c           |    2 +-
 hw/etraxfs_eth.c           |    3 +-
 hw/etraxfs_pic.c           |    3 +-
 hw/etraxfs_ser.c           |    3 +-
 hw/etraxfs_timer.c         |    3 +-
 hw/fdc.c                   |    6 +-
 hw/fw_cfg.c                |    6 +-
 hw/g364fb.c                |    3 +-
 hw/grackle_pci.c           |    6 +-
 hw/gt64xxx.c               |    9 +--
 hw/heathrow_pic.c          |    5 +-
 hw/hpet.c                  |    3 +-
 hw/ide/macio.c             |    3 +-
 hw/ide/mmio.c              |    6 +-
 hw/integratorcp.c          |    9 ++-
 hw/intel-hda.c             |    3 +-
 hw/ioapic.c                |    3 +-
 hw/isa.h                   |    2 +-
 hw/isa_mmio.c              |  100 ++++++------------------------
 hw/ivshmem.c               |    2 +-
 hw/jazz_led.c              |    3 +-
 hw/lan9118.c               |    3 +-
 hw/lance.c                 |    3 +-
 hw/lsi53c895a.c            |    6 +-
 hw/m48t59.c                |    3 +-
 hw/mac_dbdma.c             |    6 +-
 hw/mac_nvram.c             |    3 +-
 hw/marvell_88w8618_audio.c |    3 +-
 hw/mcf5206.c               |    3 +-
 hw/mcf5208.c               |    6 +-
 hw/mcf_fec.c               |    3 +-
 hw/mcf_intc.c              |    3 +-
 hw/mcf_uart.c              |    3 +-
 hw/mips_jazz.c             |   13 ++---
 hw/mips_malta.c            |    3 +-
 hw/mips_mipssim.c          |    6 +--
 hw/mips_r4k.c              |    9 +--
 hw/mpcore.c                |    3 +-
 hw/msix.c                  |    3 +-
 hw/mst_fpga.c              |    2 +-
 hw/musicpal.c              |   24 +++++---
 hw/omap.h                  |    3 +-
 hw/omap1.c                 |   42 +++++++------
 hw/omap2.c                 |    4 +-
 hw/omap_dma.c              |    4 +-
 hw/omap_dss.c              |    2 +-
 hw/omap_gpio.c             |    2 +-
 hw/omap_gpmc.c             |    2 +-
 hw/omap_i2c.c              |    2 +-
 hw/omap_intc.c             |    4 +-
 hw/omap_l4.c               |    5 +-
 hw/omap_lcdc.c             |    2 +-
 hw/omap_mmc.c              |    2 +-
 hw/omap_sdrc.c             |    2 +-
 hw/omap_sx1.c              |   15 +++--
 hw/omap_uart.c             |    2 +-
 hw/onenand.c               |    2 +-
 hw/openpic.c               |   29 ++-------
 hw/palm.c                  |   12 +++-
 hw/parallel.c              |    3 +-
 hw/pci_host.c              |  101 ++++++------------------------
 hw/pci_host.h              |    6 +-
 hw/pcie_host.c             |    3 +-
 hw/pckbd.c                 |    3 +-
 hw/pcnet.c                 |    3 +-
 hw/pflash_cfi01.c          |    6 +-
 hw/pflash_cfi02.c          |    4 +-
 hw/pl011.c                 |    3 +-
 hw/pl022.c                 |    3 +-
 hw/pl031.c                 |    3 +-
 hw/pl050.c                 |    3 +-
 hw/pl061.c                 |    3 +-
 hw/pl080.c                 |    3 +-
 hw/pl110.c                 |    3 +-
 hw/pl181.c                 |    4 +-
 hw/pl190.c                 |    3 +-
 hw/ppc405_boards.c         |    6 +-
 hw/ppc405_uc.c             |   11 ++-
 hw/ppc440.c                |    2 +-
 hw/ppc4xx_pci.c            |   19 +-----
 hw/ppc_newworld.c          |    5 +-
 hw/ppc_oldworld.c          |    2 +-
 hw/ppc_prep.c              |   40 ++-----------
 hw/ppce500_mpc8544ds.c     |    2 +-
 hw/ppce500_pci.c           |    9 ++-
 hw/prep_pci.c              |    3 +-
 hw/pxa2xx.c                |   25 ++++----
 hw/pxa2xx_dma.c            |    2 +-
 hw/pxa2xx_gpio.c           |    2 +-
 hw/pxa2xx_keypad.c         |    2 +-
 hw/pxa2xx_lcd.c            |    2 +-
 hw/pxa2xx_mmci.c           |    2 +-
 hw/pxa2xx_pcmcia.c         |    6 +-
 hw/pxa2xx_pic.c            |    2 +-
 hw/pxa2xx_timer.c          |    2 +-
 hw/r2d.c                   |    3 +-
 hw/rc4030.c                |    6 +-
 hw/realview.c              |    3 +-
 hw/realview_gic.c          |    3 +-
 hw/rtl8139.c               |   15 +----
 hw/sbi.c                   |    3 +-
 hw/serial.c                |    6 +-
 hw/sh7750.c                |    6 +-
 hw/sh_intc.c               |    3 +-
 hw/sh_pci.c                |    7 +-
 hw/sh_serial.c             |    3 +-
 hw/sh_timer.c              |    3 +-
 hw/slavio_intctl.c         |    3 +-
 hw/slavio_misc.c           |   24 +++++---
 hw/slavio_timer.c          |    3 +-
 hw/sm501.c                 |    9 ++-
 hw/smc91c111.c             |    3 +-
 hw/sparc32_dma.c           |    3 +-
 hw/spitz.c                 |    2 +-
 hw/stellaris.c             |   12 +++-
 hw/stellaris_enet.c        |    3 +-
 hw/sun4c_intctl.c          |    3 +-
 hw/sun4m_iommu.c           |    3 +-
 hw/sun4u.c                 |    4 +-
 hw/syborg_fb.c             |    3 +-
 hw/syborg_interrupt.c      |    3 +-
 hw/syborg_keyboard.c       |    3 +-
 hw/syborg_pointer.c        |    3 +-
 hw/syborg_rtc.c            |    3 +-
 hw/syborg_serial.c         |    3 +-
 hw/syborg_timer.c          |    3 +-
 hw/syborg_virtio.c         |    3 +-
 hw/tc6393xb.c              |    2 +-
 hw/tcx.c                   |    5 +-
 hw/tusb6010.c              |    2 +-
 hw/unin_pci.c              |   26 +++++---
 hw/usb-ohci.c              |   10 +---
 hw/versatile_pci.c         |   21 +------
 hw/versatilepb.c           |    3 +-
 hw/vga-isa-mm.c            |    6 +-
 hw/vga.c                   |    3 +-
 hw/vmware_vga.c            |    2 +-
 hw/wdt_i6300esb.c          |    3 +-
 hw/xilinx_ethlite.c        |    2 +-
 hw/xilinx_intc.c           |    2 +-
 hw/xilinx_timer.c          |    3 +-
 hw/xilinx_uartlite.c       |    3 +-
 hw/zaurus.c                |    2 +-
 rwhandler.c                |    4 +-
 rwhandler.h                |    2 +-
 169 files changed, 662 insertions(+), 597 deletions(-)