Re: [PATCH] lsi53c895a: disable reentrancy detection for MMIO region, too

[Thomas Huth]

On 16/05/2023 11.27, Alexander Bulekov wrote:
> On 230516 1105, Thomas Huth wrote:
> > While trying to use a SCSI disk on the LSI controller with an
> > older version of Fedora (25), I'm getting:
> >
> >   qemu: warning: Blocked re-entrant IO on MemoryRegion: lsi-mmio at addr: 0x34
>
> Do you have a gdb backtrace for this one or is there some easy way to
> reproduce with just a LiveCD or something?

I reproduced it like this:

./qemu-system-x86_64 -accel kvm -m 2G -machine q35 \
 -device lsi53c810,id=lsi1 -device scsi-hd,drive=d0 \
 -drive if=none,id=d0,file=.../somedisk.qcow2 \
 -cdrom Fedora-Everything-netinst-i386-25-1.3.iso

Where somedisk.qcow2 is an image that contains already some partitions and 
file systems.

In the boot menu of Fedora, go to "Troubleshooting" -> "Rescue a Fedora 
system" -> "3) Skip to shell"

Then check "dmesg | grep -i 53c" for failure messages, and try to mount a 
partition from somedisk.qcow2

> Marking mmio_io re-entrancy
> safe would bring back https://gitlab.com/qemu-project/qemu/-/issues/1563
> Maybe there is some other workaround here?

I think we manually have to disallow endless reentrancy in 
lsi_execute_script() ... I'm currently doing some experiments there...

 Thomas