Re: [PATCH] hw/acpi: Set memory regions to native endian as a work around

[BALATON Zoltan]

On Mon, 8 Nov 2021, Paolo Bonzini wrote:
> On 11/8/21 15:30, Paolo Bonzini wrote:
> > On 11/8/21 14:05, BALATON Zoltan wrote:
> > > When using ACPI on big endian machine (such as ppc/pegasos2 which has
> > > a VT8231 south bridge with ACPI) writes to ACPI registers come out
> > > byte swapped. This may be caused by a bug in memory subsystem but
> > > until that is fixed setting the ACPI memory regions to native endian
> > > makes it usable for big endian machines. This fixes ACPI shutdown with
> > > pegasos2 when using the board firmware for now.
> > > This could be reverted when the memory layer is fixed.
> >
> > What is the path to the swapped writes?  Even just a backtrace might be 
> > enough to understand what's going on, and especially where the bug is.
>
> Ok, Michael pointed me at 
> https://lore.kernel.org/all/20211011080528-mutt-send-email-mst@kernel.org/.

I was about to say that here's the original thread:

https://lists.nongnu.org/archive/html/qemu-devel/2021-10/msg01972.html

and here's the backtrace:

#0  acpi_pm1_cnt_write (val=40, ar=0x55555695f340) at ../hw/acpi/core.c:556
#1  acpi_pm_cnt_write (opaque=0x55555695f340, addr=1, val=40, width=2) at 
../hw/acpi/core.c:602
#2  0x0000555555b3a82f in memory_region_write_accessor
    (mr=mr@entry=0x55555695f590, addr=1, value=value@entry=0x7fffefffdd08, 
size=size@entry=2, shift=<optimized out>, mask=mask@entry=65535, attrs=...)
    at ../softmmu/memory.c:492
#3  0x0000555555b3813e in access_with_adjusted_size
    (addr=addr@entry=1, value=value@entry=0x7fffefffdd08, size=size@entry=1, 
access_size_min=<optimized out>, access_size_max=<optimized out>, access_fn=
    0x555555b3a7b0 <memory_region_write_accessor>, mr=0x55555695f590, 
attrs=...) at ../softmmu/memory.c:554
#4  0x0000555555b3c449 in memory_region_dispatch_write (mr=mr@entry=0x55555695f590, addr=1, 
data=<optimized out>, op=<optimized out>, attrs=attrs@entry=...)
    at ../softmmu/memory.c:1511
#5  0x0000555555b2c121 in flatview_write_continue
    (fv=fv@entry=0x7fff84d23b30, addr=addr@entry=4261416709, attrs=attrs@entry=..., 
ptr=ptr@entry=0x7fffefffdec0, len=len@entry=1, addr1=<optimized out>,
     l=<optimized out>, mr=0x55555695f590) at host-utils.h:165
#6  0x0000555555b2c399 in flatview_write (len=1, buf=0x7fffefffdec0, attrs=..., 
addr=4261416709, fv=0x7fff84d23b30) at ../softmmu/physmem.c:2822
#7  subpage_write (opaque=<optimized out>, addr=<optimized out>, value=<optimized 
out>, len=1, attrs=...) at ../softmmu/physmem.c:2488
#8  0x0000555555b380de in access_with_adjusted_size
    (addr=addr@entry=3845, value=value@entry=0x7fffefffdf88, size=size@entry=1, 
access_size_min=<optimized out>, access_size_max=<optimized out>, access_fn=
    0x555555b3aa80 <memory_region_write_with_attrs_accessor>, 
mr=0x7fff84710bb0, attrs=...) at ../softmmu/memory.c:549
#9  0x0000555555b3c449 in memory_region_dispatch_write (mr=mr@entry=0x7fff84710bb0, 
addr=addr@entry=3845, data=<optimized out>, data@entry=40, op=op@entry=MO_8, 
attrs=...)
    at ../softmmu/memory.c:1511
#10 0x0000555555c07b4c in io_writex
    (env=env@entry=0x55555666a820, iotlbentry=iotlbentry@entry=0x7fff843367f0, 
mmu_idx=1, val=val@entry=40, addr=addr@entry=4261416709,
     retaddr=retaddr@entry=140736116523268, op=MO_8) at 
../accel/tcg/cputlb.c:1420
#11 0x0000555555c0b5df in store_helper (op=MO_8, retaddr=<optimized out>, 
oi=<optimized out>, val=40, addr=4261416709, env=0x55555666a820) at 
../accel/tcg/cputlb.c:2355
#12 full_stb_mmu (env=0x55555666a820, addr=4261416709, val=40, oi=<optimized 
out>, retaddr=140736116523268) at ../accel/tcg/cputlb.c:2404
#13 0x00007fffae3b8104 in code_gen_buffer ()
#14 0x0000555555bfcfab in cpu_tb_exec (cpu=cpu@entry=0x555556661360, 
itb=itb@entry=0x7fffae3b7fc0 <code_gen_buffer+56197011>, 
tb_exit=tb_exit@entry=0x7fffefffe668)
    at ../accel/tcg/cpu-exec.c:357
#15 0x0000555555bfe089 in cpu_loop_exec_tb (tb_exit=0x7fffefffe668, last_tb=<synthetic 
pointer>, tb=0x7fffae3b7fc0 <code_gen_buffer+56197011>, cpu=0x555556661360)
    at ../accel/tcg/cpu-exec.c:833
#16 cpu_exec (cpu=cpu@entry=0x555556661360) at ../accel/tcg/cpu-exec.c:992
#17 0x0000555555c1bba0 in tcg_cpus_exec (cpu=cpu@entry=0x555556661360) at 
../accel/tcg/tcg-accel-ops.c:67
#18 0x0000555555c1c3d7 in rr_cpu_thread_fn (arg=arg@entry=0x555556661360) at 
../accel/tcg/tcg-accel-ops-rr.c:214
#19 0x0000555555d5c049 in qemu_thread_start (args=0x7fffefffe750) at 
../util/qemu-thread-posix.c:556
#20 0x00007ffff6a95dea in start_thread () at /lib64/libpthread.so.0
#21 0x00007ffff69c8fdf in clone () at /lib64/libc.so.6