Re: [PATCH v9 0/8] memory: prevent dma-reentracy issues

[Alexander Bulekov]

On 230427 1504, Thomas Huth wrote:
> On 26/04/2023 18.19, Alexander Bulekov wrote:
> > v8-> v9:
> >      - Disable reentrancy checks for raven's iomem (Patch 8)
> >      - Fix non-bisectable disable_reentrancy_guard patch by squashing it
> >        into Patch 1.
> >      - Fix trailing whitespace
> 
> Sorry for not noticing earlier (I think the test is not run on gitlab-CI),
> but I just noticed another failing avocado test:
> 
> tests/venv/bin/avocado --show console run \
>  tests/avocado/tuxrun_baselines.py:TuxRunBaselineTest.test_x86_64
> 
> ... seems to hang now (and finally gets "INTERRUPTED").
> 
> If I got that right, the test is basically more or less doing:
> 
>  wget https://storage.tuxboot.com/x86_64/bzImage
>  wget https://storage.tuxboot.com/x86_64/rootfs.ext4.zst
>  unzstd rootfs.ext4.zst
>  qemu-system-x86_64 -cpu Nehalem -M q35 -kernel bzImage \
>   -hda rootfs.ext4 -m 2G -append "root=/dev/sda console=ttyS0" \
>   -serial stdio
> 
> Then log in as "root" and shut down with "halt".
> 
> The "halt" works fine with git master, but it fails for me when I have your
> patches applied. Could you please have a look?

#0  trace_memory_region_reentrant_io  at trace/trace-softmmu.h:335
#1  0x0000555555fad303 in access_with_adjusted_size  at ../softmmu/memory.c:549
#2  0x0000555555fad0eb in memory_region_dispatch_write  at 
../softmmu/memory.c:1531
#3  0x0000555555fbb543 in address_space_stl_internal  at 
../memory_ldst.c.inc:319
#4  0x0000555555f29149 in stl_le_phys  at 
/home/alxndr/Development/qemu-demo/qemu/include/exec/memory_ldst_phys.h.inc:121
#5  ioapic_service  at ../hw/intc/ioapic.c:138
#6  0x0000555555f28bd1 in ioapic_eoi_broadcast  at ../hw/intc/ioapic.c:286
#7  0x0000555555f26e4a in apic_eoi  at ../hw/intc/apic.c:432
#8  0x0000555555f2687c in apic_mem_write  at ../hw/intc/apic.c:788
#9  0x0000555555fad3f9 in memory_region_write_accessor  at 
../softmmu/memory.c:493
gef➤  p ((MemoryRegion*)mr)->name
$2 = 0x5555578cbbe0 "apic-msi"

I'll send a patch to mark this re-entrancy safe based-on this series.
-Alex