[libvirt][PATCH v13 0/6] Support query and use SGX

[Yang, Lin A]

> This version is a bit better than the previous one. But we're at version
> 13 and I am still unable to even start a guest. Please, make sure that this
> basic functionality works in v14, because this is plain waste of precious
> review bandwidth.
> 
> Anyway, as usual, I've uploaded my suggested fixes here:
> 
> https://gitlab.com/MichalPrivoznik/libvirt/-/commits/sgx/

Sorry to hear it didn't work in your environment. We definitely tested it
several times and it works well for both QEMU 6.2.0 and 7.0.0.

Let me try to reproduce it with the domain xml you shared before.

By my best guess, if you see "qemu-system-x86_64:***: 
invalid object type: memory-backend-epc" error, it means QEMU didn't
get enough permission to launch SGX VM.

Pls add /dev/sgx_vepc, /dev/sgx_enclave and /dev/sgx_provision to the 
"cgroup_device_acl" list in /etc/libvirt/qemu.conf. QEMU requires those access
to assign EPC, but it was denied  by libvirt’s cgroup controllers by default.

cgroup_device_acl = [  
    "/dev/null", "/dev/full", "/dev/zero",  
    ...
    "/dev/sgx_vepc", 
    "/dev/sgx_enclave”, 
    "/dev/sgx_provision” 
] 

Also in /etc/libvirt/qemu.conf, set the runtime user to uid 0,  since QEMU needs to
read and write to those sgx devices, like /dev/sgx_vepc. Unfortunately, it is owned
by root with file mode 600, so QEMU has to launch as root. 

user = "+0"

It would be really helpful if you can use these steps to see whether it resolve 
the issue. I will add a doc somewhere to include all steps are required for use to
use sgx in libvirt.

Thanks,
Lin.