address_space_stw_le_cached: Assertion `addr < cache->len && 2 <= cache ->len - addr' failed

[Frank Denis]

When running OpenBSD-current as a guest, the following assertion is hit after a few seconds, resulting in the virtual machine to crash:

```
qemu-system-x86_64: /build/qemu/src/qemu-3.0.0/include/exec/memory_ldst_cached.inc.h:85: address_space_stw_le_cached: Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
```

Host is Arch Linux stable, running on x86_64.

Qemu version is 3.0.0, installed via the standard Arch Linux package.

Version 2.12.1 didn't exhibit this behavior.

[Thomas Huth (th-huth)]

Do you know how to use "git bisect"? If so, could you maybe try to bisect which commit between v2.12.0 and v3.0.0 introduced this problem?

[Peter Maydell (pmaydell)]

I suspect this is a known bug, fixed in master in commit db812c4073c77. You could test that by cherry-picking it to 3.0 or just testing against master.

[Peter Maydell (pmaydell)]

In the absence of further information from the submitter, it seems reasonable to assume that this is indeed the bug fixed by commit db812c4073c77 (which resulted in this assertion when running OpenBSD guests). That commit is in 3.1, which was released in December.