When running 20.04 in ppc64el as KVM host I am not able to compose virtual machines

[Diego Mascialino]

Instructions:

 * Select a ppc64el machine
 * Deploy Ubuntu 20.04 and check "Register as MAAS KVM host."
 * Go to KVM tab
 * Select the deployed machine and try to `Compose` a new one.

This error is shown:
```
Error:Pod unable to compose machine: Unable to compose machine because: Failed talking to pod: Unable to compose nearby-poodle: error: Failed to start domain nearby-poodle error: internal error: qemu unexpectedly closed the monitor: 2021-03-03T20:57:48.147690Z qemu-system-ppc64le: Requested safe cache capability level not supported by kvm, try appending -machine cap-cfpc=broken
```

MAAS version: 2.9.3~alpha1 (9176-g.2c0686e4b)

PS: I was able to compose machine when running 18.04 in ppc64el

[Bill Wear (billwear)]

i verified this live with Diego. triaging.

[Patricia Domingues (patriciasd)]

Hi Diego, could you let me know on which system did you try it?
machine/model type please.

[Alberto Donato (ack)]

Hi Patricia,

this is a machine in our CI lab:

processor : 152
cpu : POWER8E (raw), altivec supported
clock : 2061.000000MHz
revision : 2.1 (pvr 004b 0201)

timebase : 512000000
platform : PowerNV
model : 8247-22L
machine : PowerNV 8247-22L
firmware : OPAL
MMU : Hash

[Patricia Domingues (patriciasd)]

Able to reproduce this issue with the following error:

Error:Pod unable to compose machine: Unable to compose machine because: Failed talking to pod: Unable to compose kvmpodvm1: error: Failed to start domain kvmpodvm1 error: internal error: qemu unexpectedly closed the monitor: 2022-05-10T19:46:25.103802Z qemu-system-ppc64le: Requested safe cache capability level not supported by kvm, try appending -machine cap-cfpc=broken

but this is due to the old firmware version (FW860.11 (SV860_063)). You need to update the firmware and then you'll be able to compose the VM.

[Patricia Domingues (patriciasd)]

tested on MAAS version: 2.9.2 on the same POWER8 machine/type reported - PowerNV 8247-22L with firmware FW860.90 (SV860_226) and was able to compose the machine

[Patricia Domingues (patriciasd)]

I'm marking this one as invalid for now, feel free to add any other info or re-open