Re: ACPI endianness

["Michael S. Tsirkin" <mst@redhat.com>]

On Sun, Oct 10, 2021 at 03:24:32PM +0200, BALATON Zoltan wrote:
> Hello,
> 
> I'm trying to fix shutdown and reboot on pegasos2 which uses ACPI as part of
> the VIA VT8231 (similar to and modelled in hw/isa/vt82c686b.c) and found
> that the guest writes to ACPI PM1aCNT register come out with wrong
> endianness but not shure why. I have this:
> 
> $ qemu-system-ppc -M pegasos2 -monitor stdio
> (qemu) info mtree
> [...]
> memory-region: pci1-io
>   0000000000000000-000000000000ffff (prio 0, i/o): pci1-io
> [...]
>     0000000000000f00-0000000000000f7f (prio 0, i/o): via-pm
>       0000000000000f00-0000000000000f03 (prio 0, i/o): acpi-evt
>       0000000000000f04-0000000000000f05 (prio 0, i/o): acpi-cnt
>       0000000000000f08-0000000000000f0b (prio 0, i/o): acpi-tmr
> 
> memory-region: system
>   0000000000000000-ffffffffffffffff (prio 0, i/o): system
>     0000000000000000-000000001fffffff (prio 0, ram): pegasos2.ram
>     0000000080000000-00000000bfffffff (prio 0, i/o): alias pci1-mem0-win @pci1-mem 0000000080000000-00000000bfffffff
>     00000000c0000000-00000000dfffffff (prio 0, i/o): alias pci0-mem0-win @pci0-mem 00000000c0000000-00000000dfffffff
>     00000000f1000000-00000000f100ffff (prio 0, i/o): mv64361
>     00000000f8000000-00000000f8ffffff (prio 0, i/o): alias pci0-io-win @pci0-io 0000000000000000-0000000000ffffff
>     00000000f9000000-00000000f9ffffff (prio 0, i/o): alias pci0-mem1-win @pci0-mem 0000000000000000-0000000000ffffff
>     00000000fd000000-00000000fdffffff (prio 0, i/o): alias pci1-mem1-win @pci1-mem 0000000000000000-0000000000ffffff
>     00000000fe000000-00000000feffffff (prio 0, i/o): alias pci1-io-win @pci1-io 0000000000000000-0000000000ffffff
>     00000000ff800000-00000000ffffffff (prio 0, i/o): alias pci1-mem3-win @pci1-mem 00000000ff800000-00000000ffffffff
>     00000000fff00000-00000000fff7ffff (prio 0, rom): pegasos2.rom
> 
> The guest (which is big endian PPC and I think wotks on real hardware)
> writes to 0xf05 in the io region which should be the high byte of the little
> endian register but in the acpi code it comes out wrong, instead of 0x2800 I
> get in acpi_pm1_cnt_write: val=0x28
> 
> The memory regions involved are:
> 
> acpi-cnt (hw/acpi/core.c):
> 
> static const MemoryRegionOps acpi_pm_cnt_ops = {
>     .read = acpi_pm_cnt_read,
>     .write = acpi_pm_cnt_write,
>     .impl.min_access_size = 2,
>     .valid.min_access_size = 1,
>     .valid.max_access_size = 2,
>     .endianness = DEVICE_LITTLE_ENDIAN,
> };
> 
> via-pm (hw/isa/vt82c686.c):
> 
> static const MemoryRegionOps pm_io_ops = {
>     .read = pm_io_read,
>     .write = pm_io_write,
>     .endianness = DEVICE_NATIVE_ENDIAN,
>     .impl = {
>         .min_access_size = 1,
>         .max_access_size = 1,
>     },
> };
> 
> Also tried removing .impl from pm_io_ops but that does not help. Changing
> acpi_pm_cnt_ops to DEVICE_NATIVE_ENDIAN fixes it but not sure what else
> could that break. Should these ACPI regions be native endian or how else to
> fix this for the vt82xx case?
> 
> Regards,
> BALATON Zoltan

Does it help if you change via to DEVICE_LITTLE_ENDIAN?

-- 
MST