Commit f7a24b2ea8 ("lib/qemu.c: Use machine type none when inspecting
QMP properties") changed the number of command line parameters used
before the '-qmp stdio' option when libguestfs queries qemu features.
This broke some tests which rely on the exact order of parameters.
Fixes: commit f7a24b2ea8
Updates: commit 5da8102f5f
On RHEL 10.2 aarch64 (only) we see:
$ echo '{ "execute": "qmp_capabilities" }' '{ "execute": "query-kvm" }' '{ "execute": "quit" }' | QEMU_AUDIO_DRV=none "/usr/libexec/qemu-kvm" -display none -machine "virt,accel=kvm:hvf:tcg" -qmp stdio
qemu-kvm: invalid accelerator hvf
qemu-kvm: falling back to KVM
{"QMP": {"version": {"qemu": {"micro": 0, "minor": 1, "major": 9}, "package": "qemu-kvm-9.1.0-15.el10_0.4"}, "capabilities": ["oob"]}}
qemu-kvm: warning: CPU model cortex-a57-arm-cpu is deprecated -- use 'host' / 'max'
qemu-kvm: kvm_init_vcpu: kvm_arch_init_vcpu failed (0): Invalid argument
Unfortunately we cannot use guestfs_int_get_cpu_model (as that
requires us to already know if KVM is supported), so we just have to
guess that -cpu max will work, at least enough for QMP to work.
Fixes: https://issues.redhat.com/browse/RHEL-121076
Reported-by: Xiang Hua Chen
Previously we tested if KVM was available, and cached that for the
qemu binary. I think this was actually wrong. For example, if the
machine restarts, then the cache is still around, but KVM might be
enabled or disabled because of a new host kernel.
In any case, let's radically simplify this.
Test for KVM on each run. Consequently we can remove all the qemu
test caching stuff as it is no longer used anywhere.
I also tightened up the code that runs the QMP query-kvm command, so
now any unexpected output will cause a runtime failure. This command
ought to work, and if it breaks we ought to know about it and fix it.
Although this test only specifically tests the direct backend, the
same code is shared with the libvirt backend in some circumstances
(eg. creating readonly drives). So this is testing a bit of both.
