Trying "make check" on OSv (https://github.com/cloudius-systems/osv), which runs a virtual machine with qemu/kvm as part of the build process, crashes on my Fedora 29 with qemu-kvm-3.0.0-1.fc29.x86_64, with the following message: OSv v0.52.0-6-gea75831f qemu-system-x86_64: /builddir/build/BUILD/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. qemu failed. The first line ("OSv...") shows the guest started running properly, but then crashed. I suspect this is the same as https://bugs.launchpad.net/qemu/+bug/1795148 and according to that tracker, the bug was solved upstream and the fix could be backported.
Thanks for finding the upstream bug, I'll try backporting it commit db812c4073c77c8a64db8d6663b3416a587c7b4a Author: Paolo Bonzini <pbonzini> Date: Thu Aug 23 14:21:23 2018 +0200 virtio: update MemoryRegionCaches when guest negotiates features
Yes, it's that commit. However f29 and rawhide builds are failing like this: https://koji.fedoraproject.org/koji/getfile?taskID=30576602&volume=DEFAULT&name=build.log&offset=-4000
qemu-3.0.0-2.fc29 has been submitted as an update to Fedora 29. https://bodhi.fedoraproject.org/updates/FEDORA-2018-87f2ace20d
qemu-3.0.0-2.fc29 has been pushed to the Fedora 29 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-87f2ace20d
I can confirm that qemu-kvm-3.0.0-2.fc29, which I got from the testing repository, via "dnf update --enablerepo=updates-testing qemu-kvm", fixes the bug. Too bad that after two weeks, it still hasn't reached the main updates repository.
I pushed it now.
qemu-3.0.0-2.fc29 has been pushed to the Fedora 29 stable repository. If problems still persist, please make note of it in this bug report.